Fall Army Worm

One day Training programme on

Fall army worm, Spodoptera frugiperda: An emerging insect-pest on Maize (On 3rd July, 2019)

Course coordinator:Dr. Uma Shankar

Organized by SAMETI-J in collaboration with Division of Entomology

Faculty of Agriculture Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu

Compendium on

Fall army worm, Spodoptera frugiperda: An emerging insect-pest on Maize (On 3rd July, 2019)

Organized by SAMETI-J in collaboration with Division of Entomology

Course coordinator:Dr. Uma Shankar

Faculty of Agriculture Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu

Contents Chapter Tilte(s) No. 1 Fall Army worm: An emerging pest on Maize

Resource person Dr. Uma Shankar

01-09

2 3

Dr. A. K. Singh Dr. R. K. Gupta

10-13 14-24

Dr. Hafeez Ahmad Dr. Devinder Sharma

25-28 29-32

4 5

Bio-ecology of Fall army worm Promising Biocontrol agents for the control of fall army worm Integrated pest management for Fall army worm Feasibility of semiochemicals for the management of Fall army worm

Pages

Chapter-1

Fall Army worm: An emerging insect-pest on Maize Dr. Uma Shankar Associate Professor Division of Entomology, Faculty of Agriculture, Sher-e-Kashmir University of Agricultural Sciences & Technology of Jammu, Chatha, Jammu-180009, J&K, India email:umashankar.ento@gmail.com,whatsapp:9419202151 _________________________________________________________________________

The term "armyworm" can refer to several species which often describing the large-scale invasive behaviour of the species' larval stage. The scientific name of Fall armyworm derives from frugiperda, which is a Latin word meaning lost fruit. It is named for its capability to damage and destroy a large variety of crops. Because of its propensity for destruction, it is the need of hour to acquaint the farming community about fall armyworm's infestation, bio-ecology and strategies for crop protection.

The genus “Spodoptera� has 25 species but S. littura, S. muritia, S. exempta and S. frugiperda are economically significant species for agricultural crops. S. frugiperda (Fall Armyworm) is an invasive pest of many crops but most serious pest for maize. It is migratory lepidopteran insect pest with more than 100 plant species.

The fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae), a polyphagous and voracious agricultural insect-pest, has been identified for the first time on the Indian subcontinent. Native to the Americas, the pest is known to eat over 80 plant species earlier, with a particular preference for maize, a main staple crop around the world. The fall armyworm, Spodoptera frugiperda, is a lepidopteran pest that feeds in large numbers on the leaves, stems and reproductive parts of more than 350 plant species, causing major damage to economically important cultivated grasses such as maize, rice, sorghum, sugarcane and wheat but also other vegetable crops and cotton. The fall armyworm (FAW), S. frugiperda have been known with several names in English as alfalfa worm; armyworm, fall; buckworm; budworm; corn budworm; corn leafworm; cotton leaf worm; daggy's corn worm; grass caterpillar; grass worm; maize budworm; overflow worm; rice caterpillar; southern armyworm; southern grassworm; wheat cutworm; whorlworm.

The fall armyworm was first officially reported in Nigeria in West Africa in 2016, and rapidly spread across 44 countries in sub-Saharan Africa. Sightings of damage to maize crops in India due to fall armyworm mark the first report of the pest in Asia. The pest has the 1

potential to spread quickly not only within India, but also to other neighboring countries in Asia, owing to suitable climatic conditions. Soon after invading the African continent, S. frugiperda was found in Asia, first in India and then in China, Myanmar and Thailand. More recently, records of the pest in new areas have been made on the Asian continent.

In India, S. frugiperda was first found in May 2018 in Karnataka. The pest then rapidly spread to other Indian states on crops of maize (Zea mays), sorghum (Sorghum spp.) and millet (Eleusine coracana – finger millet, Panicum sumatrense– little millet, Pennisetum glaucum – pearl millet, Setaria italica – foxtail millet). As of March 2019, the presence of S. frugiperda was confirmed in the following Indian states: Andhra Pradesh, Bihar, Chhattisgarh, Gujarat, Karnataka, Maharashtra, Orissa, Tamil Nadu, Telangana, and West Bengal.

Finally, outbreaks of S. frugiperda have recently been confirmed in Bangladesh and Sri Lanka. It is evident that the outbreak of Fall armyworm (Spodoptera frugiperda) has affected maize cultivation in 1,747.9 hectares in 122 villages and caused Rs 20 cr crop loss in Mizoram, India (The Hindu, 2019). Moreover, it has been predicted that FAW could cause up to $US13 billion per annum in crop losses throughout sub-Saharan Africa, thereby threatening the livelihoods of millions of poor farmers. Fall Armyworm, the dreaded pest and considered

a

threat

to

global

food

security

in

coming

time.

Being a nocturnal pest, the FAW hides under maize leaves at day time and is difficult to detect. In continuation, outbreak of lepidopteran pests in Jammu sub-tropics on onion and other crops have also been recorded during 2015 rabi and kharif season (Ref. All India Network Reasearch Project on Onion and Garlic, Annual Report 2014‐15).

Outbreak of Lepidopteran pests in Jammu sub-tropics on onion Apart from the major and regular insect pests, a serious outbreaks of lepidopteran insectpests have been recorded during April, 2015 infesting both onion and garlic crops in Jammu subtropics. The outnumbered populations of lepidopteran pests such as Helicoverpa armigera and Spodoptera frugiperda completely devastated the existing crops and infested onion and garlic crops also at the time of maturity. A gregarious mass of larval parasitoids named Cotesia congregata on S. frugiperda have also been observed from the trials of rabi onion and garlic and this constitutes the first ever record from Jammu region. Besides, Cotesia, another larval parasitoid of H. armigera named Campoletes chloriedeae have been recorded on large scale from onion apart from other crops like marigold, roses, gladiolus, wheat etc.

2

Distribution S. frugiperda is native to tropical and subtropical regions of the Americas. In 2016 it was reported for the first time from the African continent, in Nigeria, Sao TomĂŠ, Benin and Togo (Goergen et al., 2016; IPPC, 2016). It has now been confirmed in more than 30 African countries (FAO, 2018). In 2018, S. frugiperda was reported from the Indian subcontinent (Ganiger et al., 2018; IITA, 2018; Sharanabasappa Kalleshwaraswamy et al., 2018), in Karnataka (ICAR-NBAIR, 2018a) and Andhra Pradesh (EPPO, 2018). The pest has also been reported in Bihar, Chhattisgarh, Gujarat, Maharashtra, Odisha, Tamil Nadu, Telangana and West Bengal (ICAR-NBAIR, 2018b; EPPO, 2019). A live tracking tool for fall armyworm in India has been developed by PEAT, CABI and ICRISAT: https://plantix.net/en/live/fallarmyworm. S. frugiperdahas also been reported in Myanmar (IPPC, 2019a), Sri Lanka (FAO, 2019a), China (IPPC, 2019), Bangladesh (FAO, 2019c), Thailand (IPPC, 2018b) and Korea Republic (IPPC, 2019b).

Distribution Table in Indian states India

Restricted

Introduced

distribution

ICAR-NBAIR, 2018a; EPPO, 2018; Ganiger et al., 2018; Sharanabasappa et al., 2018

Andhra

Restricted

Introduced

Pradesh

distribution

Bihar

Present

EPPO, 2019

Chhattisgarh

Present

EPPO, 2019

Gujarat

Present

EPPO, 2019

Karnataka

Restricted

Introduced

distribution

2018 ICAR-NBAIR, 2018b; EPPO, 2018

2018 ICAR-NBAIR, 2018a; ICAR-NBAIR, 2018b; EPPO, 2018; Ganiger et al., 2018; IITA, 2018; Sharanabasappa and Kalleshwara swamy, 2018; Sharanabasappa et al., 2018

Maharashtra

Present

Odisha

Present

Introduced

2018 ICAR-NBAIR, 2018b; EPPO, 2018 EPPO, 2019

3

Tamil Nadu

Present

West Bengal

Present

Introduced

2018 ICAR-NBAIR, 2018b; EPPO, 2018 EPPO, 2019

Risk of Introduction S. frugiperda is on the EPPO A1 list of quarantine pests and is intercepted occasionally in Europe on imported plant material (Seymour et al., 1985). From Africa alone, in 2017, two consignments containing fall armyworm were intercepted in Europe, and 17 interceptions were

made

in

the

first

8 months

of

2018

from

wide-ranging

crops

including Capsicum, Coriandrum, Eryngium, Eustoma, Pisum, Rosa, Solanum and Zea mays (EUROPHYT).

Hosts/Species Affected S. frugiperda is a polyphagous pest which shows a definite preference for the Poaceae (Casmuz et al., 2010). It is most commonly recorded from wild and cultivated grasses; from maize, rice, sorghum and sugarcane. However, Montezano et al. (2018) have recently reported 353 host plant species based on a thorough literature review, and additional surveys in Brazil, from 76 plant families, principally Poaceae (106), Asteraceae (31) and Fabaceae (31 families).

Growth Stages Flowering stage, Fruiting stage, Seedling stage, Vegetative growing stage Symptoms Seedlings are fed upon within the whorl. Larger larvae can cut the base of the plant. Mature plants suffer attack on reproductive structures. On tomato plants, buds and growing points may be eaten and fruits pierced. Maize leaves are eaten and the whorl (funnel) may be a mass of holes, ragged edges and larval frass. Young larvae skeletonize the leaf lamina in a typical 'window-pane' damage. 'Window-paning' is the most common damage symptom at early whorl; however, this is sometimes indistinguishable from damage that is due to other stem borers. Usually many young larvae will be present on the same plant, but normally one or two older larvae may be found on a single plant, as others will migrate and feed on neighbouring plants. Later larval instars make larger holes, causing ragged whorl leaves, and produce sawdust-like larval droppings, while fresh feeding produces big lumps. Badly infested fields may look as if they have been hit by a severe hailstorm. Fall armyworm can also destroy silks and developing tassels, thereby limiting fertilization of the ear. Maize plants may have the

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cobs attacked by larvae boring through the kernels. Damage to cobs may lead to fungal infection and aflatoxins, and loss of grain quality. At high densities, large larvae may act as armyworms and disperse in swarms, but they often remain in the locality on wild grasses, if available.

Genetic differentiation of fall armyworm Fall armyworm occurs in two races: a ‘rice strain’ (R strain) and a ‘corn strain’ (C strain) (Lu and Adang, 1996; Lewter et al., 2006; Nagoshi et al., 2007); the former is thought to preferentially feed on rice and various pasture grasses and the latter on maize, cotton and sorghum. The strains are morphologically identical, but can be distinguished by molecular techniques. Recent evidence shows that the diversity of fall armyworm that invaded Africa is greater than previously thought, including a haplotype that has not yet been observed in the Western Hemisphere (Nagoshi et al., 2018). Analyses of South African specimens indicate corn and rice strains are both present (Jacobs et al., 2018). In Uganda, fall armyworm populations were found to consist of two sympatric sister species of maize-preferred and ricepreferred strains (Otim et al., 2018). There have been some attempts to establish the origin of these strains, and evidence from Ghana (Cock et al., 2017) and Togo (Nagoshi et al., 2018) suggests that the populations are most similar to that found in the Caribbean region and the eastern coast of the USA. Identification and Life History There are two white spots present on forewings. Female lays eggs on stalks, underside the leaves and also upper side the leaves which are covered by layers of hairy scales. Its pupae are dark brown in color. New born larvae are green in color and become light tan to black. It has inverted “Y” symbol on head which differentiate it from other species. Adult moth lives up approximately 21 days and average 10 days. Female is larger than male in size and lays 1500 to 2000 eggs in her life span. Their life cycle complete in 21-40 days. Cannibalistic behavior occurs in larval stages in which larger larvae feed on smaller in case of food shortage. There are 8 no. of generations per year. They are strong flier and migrate very vastly from one area to another. They mate through releasing sex pheromones and create confliction among males. They also feed on nectar of flowers at night.

5

Damage and its Symptoms Neonate’s larvae feed on leaf gregariously and leaf becomes dry, then larvae move to other leaf for feeding. At mature stages they feed on leaves severely and only midrib and veins will be standing in the field without leaves. Previous researches have been proved that they are known as chief deflator. In case of cotton, at flowering and boll formation stage they feed on internal contents. They make irregular holes on the leaves. Leaves of maize plant eaten and whorl may be a mass of holes, ragged edges and larval frass. Young larvae dry up the leaf lamina. Severe feeding by larvae can kill growing points of crop plant. Larvae can also attack on cob Monitoring Corn growers should pay close attention to late planted fields or fields with a history of these problems. Problems are usually associated fields planted in first week of June. Early detection of infestations will allow for more effective control of this pest. Therefore, We should monitor the field daily for moth inspection using traps even before planting. We should look for light green to dark brown larvae with 3 thin yellowish white stripes down the back and distinct white inverted “Y� on the dark. We should look for elongated holes on the leaves and inside whorls of young plants. We should look for blotches of small (Window Pane) to large ragged and elongated holes in the leaves emerging form whorl with yellowish brown frass. Finding an infestation after it is too late to obtain good control is a serious and common problem. Because fall armyworm prefers whorl stage corn, late planted fields should be given a high priority when scouting.

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Cultural control We should avoid late of off season planting to avoid population build up. We should remove crop residue and all alternate hosts. Plant should be at correct spacing and use of optimum fertilizers for crop. We should not move infested maize material from one field to another to prevent infestation. We should put a half handful of sand/ sawdust or soil in the attacked plants to kill the larvae. We should apply a pinch of 50 gm ground hot pepper + 2 kg ash into plant funnel at knee high. We should use various pheromone traps to predict and identify the risk areas (high, medium and low).

Threshold level for FAW Control needs to be considered when egg masses are present on 5% of the plants or when 25% of the plants show damage symptoms and live larvae are still present. Controlling larger larvae, typically after they are hidden under the frass plug, will be much more difficult.

Biological control There are various parasitoids that can be used to control this pest including; Trichogramma pretiosum, T. atopoviriliaegg parasitoids (100000 per ha) and Telenomus remus (25003000). Fly and wasp parasitoids target the fall armyworm including; Archytas marmoratus, Cotesia marginiventris and Chelonus texanus .

Predators, parasitoids and parasites Caterpillars of fall armyworm are directly preyed on by many invertebrates and vertebrates like birds, rodents, beetles, earwigs, bugs and predatory wasp (Figures 4 and 5).

Genetic control We can control insect pest especially lepidopterans through Bacillus thuringiensis (Bt) varieties.

7

Bio pesticides Insect pests of crops including; Nucleo polyhedron viruses (NPV), Iridovirsus, Metarhizium anisopliae, Beuaveria Bassiana (Fungi) and Bacillus thuringiensis (Bt) (Bacteria) (“Javelin� trade name).

Botanicals Plant essential oils and neem based anti-feedent or insecticidal products can also be used to control pests including; Azadirachtin, Align, Azatin, Ecozin, Neemazal, Neememusion, Neemix, and Ornazin.

Recommended Chemicals against Fall Armyworm There are various chemicals which can be used to control fall armyworm. Chemicals including; Indoxacarb, Emamectin benzoate, Flubediamide, Lufenuron, Methomyl, Malathon and Chlorpyrifos.

Management Treatments must be applied before larvae burrow deep into the whorl or enter ears of more mature plants. Insecticide applications by ground rig using at least 30 gallons per acre and high pressure will give the best results. In pre tassel corn, direct spray directly over the whorl.

There is some suppression of fall armyworm larvae with some types of Bt corn such as the Yield Gard and to a lesser extent Knockout/Nature Gard. Herculex does provide the best fall armyworm control among the different types of Bt corn. However, with later planting dates (after June 1st week) and high fall armyworm levels, all Bt corn hybrids will need to be monitored for fall armyworm activity and treated with an insecticide according to the above economic threshold.

Agro-ecological approaches offer culturally appropriate low-cost pest control strategies that can be readily integrated into existing efforts to improve smallholder incomes and resilience through sustainable intensification. Such approaches should therefore be promoted as a core component of integrated pest management (IPM) programmes for FAW in combination with crop breeding for pest resistance, classical biological control and selective use of safe pesticides.

8

Conclusion The evidence indicates that several measures can be adopted immediately for controlling fall armyworm (FAW). These include (i) sustainable soil fertility management and weed management; (ii) intercropping with appropriately selected companion plants; and (iii) diversifying the farm environment through management of (semi) natural habitats at multiple spatial scales with multi-tactical ecologically based IPM.

9

Chapter-2

Bio-ecology of Fall army worm Dr. Amit Kumar Singh Associate Professor Division of Entomology, Faculty of Agriculture, Sher-e-Kashmir University of Agricultural Sciences & Technology of Jammu, Chatha, Jammu-180009, J&K, India email: __________________________________________________________________________ The fall armyworm, Spodoptera frugiperda (J. E. Smith), has been classified as a sporadic pest due to its migratory behavior. This species does not enter diapause, so it migrates from warmer climates such as southern Florida, Caribbean Islands, southern Texas, Mexico, and coastal areas of southern Georgia, Alabama, Mississippi, and Louisiana, northward across the United States annually (Luginbill 1928, Sparks 1979, Knipling 1980, Ashley et al. 1989, Adamczyk 1998). Fall armyworm movement each year generally creates sporadic problems across multiple crops, including maize (Zea mays L.). Fall armyworm outbreaks and subsequent damage can be unpredictable. When outbreaks do occur, the severity of the problem is compounded by the ability of fall armyworm to damage a range of vegetative to reproductive plant structures, creating the opportunity to cause devastating crop losses.

Biology of armyworm (Spodoptera frugiperda) Fall armyworm can be one of the more difficult insect pests to control in field maize/corn.

Late planted fields and later maturing hybrids are more likely to become infested. It causes serious leaf feeding damage as well as direct injury to the ear. While fall armyworms can damage corn plants in nearly all stages of development, it will concentrate on later plantings that have not yet silked. Like European corn borer, fall armyworm can only be effectively controlled while the larvae are small. Early detection and proper timing of an insecticide application are critical.

The fall armyworm has several generations per year, with the life cycle consisting of egg, six to seven larval instars, pupa, and adult.

Adult FAW Moth As moths emerge from the soil, they can mate locally or migrate up to 300 miles before mating and ovipositing (Ashley et al., 1989).

10

Eggs are generally laid on the abaxial (underside) surface of leaves; however, when oviposition frequency in a cotton field is high, females will oviposit eggs on all plant structures (Luginbill 1928, Sparks 1979, Ali 1989). The most preferred location for oviposition is on leaves emerging directly from the main stem in the middle to lower portion of the plant canopy (Ali 1989). The spherical gray eggs are laid in clusters 50 to 150, usually on the leaves. Egg masses are covered with a coating of moth scales or fine bristles. Larvae hatch in 3 to 5 days and move to the whorl.

FAW Larva Upon eclosion, neonates consume the egg mass from which they hatched. Larvae then disperse in all directions, beginning to feed on vegetative tissue. Later instars prefer to feed on reproductive structures such as squares (flower buds) and bolls. Larval feeding and adult activity most frequently occurs at night, but can occur in late evening and early morning. Number of instars can range from six to seven depending on environmental conditions and availability of food.

The final instar will consume a greater quantity of food than all previous instars combined (Luginbill, 1928). The length of time for larval development (hatching to pupation) varies based on temperature and environmental conditions, but can range from 11 to 50 d (Luginbill 1928; Hogg et al., 1982). At 25°C larval development on cotton takes 22 days (Pitre and Hogg 1983). Fall armyworm larva vary from light tan to black with three light yellow stripes down the back. There is a wider dark stripe and a wavy yellow-red blotched stripe on each side. Larvae have four pairs of fleshy abdominal prolegs in addition to the pair at the end of the body.Fall armyworm resembles both armyworm and corn earworm, but fall armyworm has a white inverted "Y" mark on the front of the dark head.

The corn earworm has a orange-brown head, while the armyworm has a brown head with dark honeycombed markings. Fall armyworm has four dark spots arranged in a square on top of the eighth abdominal segment.

Larvae fall from the plant and burrow into soil to a depth of one to three inches in the soil, remain in a pre pupal state for 2–4 d, and pupate there for 7–10 d (Luginbill, 1928; Pitre and

11

Hogg, 1983). Depth of pupation is dependent upon factors such as soil texture, soil moisture, and soil temperature (Sparks, 1979).

FAW Damage Very early symptoms of fall armyworm resemble European corn borer infestation. Small holes and "window pane" feeding in the leaves emerging from the whorl are common.

Although initial symptoms of damage are similar, thresholds and control measures differ.

Therefore it is important to find the live larvae and determine which insect is causing the damage. Unlike armyworm, fall armyworm feeds during the day and night, but are usually most active in the morning or late afternoon.

The most common damage is to late pretassel corn. Larger fall armyworm larvae consume large amounts of leaf tissue resulting in a ragged appearance to the leaves similar to grasshopper damage. Larger larvae are usually found deep in the whorl often below a "plug" of yellowish brown frass. Beneath this plug, larvae are protected somewhat from insecticide applications. Plants often recover from whorl damage without any reduction in yield.

Larvae will also move to the ear as plants begin to tassel and young ears become available.

The ear may be partly or totally destroyed. Damage to the ear may be much more important than leaf damage.

A threshold temperature of 10.9째C and 559 day-degrees C is required for development.

Sandy-clay or clay-sand soils are suitable for pupation and adult emergence. Emergence in sandy-clay and clay-sand soils was directly proportional to temperature and inversely proportional to humidity. Above 30째C the wings of adults tend to be deformed. Pupae require a threshold temperature of 14.6째C and 138 day-degrees C to complete their development (Ramirez-Garcia et al., 1987).

S. frugiperda is a tropical species adapted to the warmer parts of the New World; the optimum temperature for larval development is reported to be 28째C, but it is lower for both oviposition and pupation. In the tropics, breeding can be continuous with four to six generations per year, but in northern regions only one or two generations develop; at lower temperatures, activity and development cease, and when freezing occurs all stages are usually killed.

Agro-ecological approaches to pest management: 1 Minimum soil disturbance enhances biological properties of soil, thereby improving soil fertility management and plant nutrition

12

2 Mulching of crop residues protects the soil surface and adds carbon to improve soil fertility management, and in addition provides habitat for insect predators especially spiders, earwigs, beetles and ants 3.Planting leguminous inter-crops or cover crops improves soil fertility management through nitrogen fixation, diversifies the field environment for beneficial insects, including insect predators and parasitoids, and through the production of olfactory cues can deter pests from laying eggs (also in the case of FAW, intercrops may trap the ballooning first instar larvae thereby increasing mortality) 4. Shrubs/trees with flowers or extra flora nectaries support populations of ants and small wasps 5. Boundary trees (e.g. fodder trees, fuelwood trees, shelter trees) provide perches and roosts for birds and bats and increase the structural diversity of the farm habitat through shade and shelter 6. Crop rotation – improves soil fertility management and diversifies the farm environment 7. Regular scouting by the farmer to identify pests and assess damage enables informed pest management decisions 8.Weeds allowed to grow between the maize rows and along field margin can provide habitat for insect predators and encourage parasitoids and predatory wasps through provision of nectar (however, weeds can also compete with the crop and sometimes provide alternative hosts for pests, hence detailed understanding of their effects is required) 9. Diverse field margins provide habitat for generalist predators, such as spiders, beetles, earwigs and ants 10. Insectivorous birds and bats provide an important role in reducing pest abundance in diverse agro-ecological systems 11. Nest site provision for predatory wasps or ants could be used to enhance the local abundance of insect predators 12. Predatory wasp – these wasps hunt pest caterpillars to provision their larvae. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

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Chapter-3

Promising Biocontrol Agents for the control of fall army worm Dr. R. K. Gupta Professor Division of Entomology, Faculty of Agriculture, Sher-e-Kashmir University of Agricultural Sciences & Technology of Jammu, Chatha, Jammu-180009, J&K, India E mail: rkguptaentoskuast@gmail.com __________________________________________________________________________ Key facts •

Fall Armyworm is an insect native to tropical and subtropical regions of the Americas

•

It was first detected in Central and Western Africa in early 2016 and has now spread across Sub-Saharan Africa and recently reached Yemen and India

•

In the larval stage, the insect causes damage to crops, feeding on more than 80 plant species

•

FAW primarily affects maize, but also rice and sorghum as well as cotton and some vegetables

•

The moth can fly up to 100 km per night and the female moth can lay up to a total of 1000 eggs in her lifetime

•

In the Americas, farmers have been managing FAW in their crops for many centuries and researches have been studying it for decades

•

Sustainable management practices that are used in the Americas need to be to be adapted to countries’ socio-economic-environmental contexts

Invasion: The Fall Armyworm (FAW), Spodoptera frugiperda, was detected for the first time on the Indian subcontinent in mid-May this year in maize fields at the College of Agriculture, University of Agricultural and Horticultural Sciences (UAHS), Shivamogga, Karnataka. This was the report of IITA Scientist Georg Goergen, who provided technical assistance in tracking the pest’s identity. Following morphological identification, Drs Sharanabasappa and Kalleshwara Swamy of UAHS confirmed the pest’s identity using molecular techniques. Similar information has also just been released based on independent investigations by the National Bureau of Agriculturally Important Microorganisms (NBAIR) under the Indian Council of Agricultural Research (ICAR).

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What are Biological and Options?

In nature, the population of any organism is regulated. It is kept fluctuating within an upper and lower threshold, often below economically damaging levels, due to the actions of biotic regulations (availability of food, parasites, predators, and/or pathogens) and/or abiotic factors (climate and soil factors). Such population regulation is referred to as natural control.

However, such natural control when disrupted due to biological, anthropogenic, or climatic factors results in the outbreak of organisms leading to economic damage. Invasiveness of a pest species into new geographies in the absence of biotic regulatory factors often results in the disruption of natural control, leading to devastating outbreaks (e.g., fall armyworm (FAW), Spodoptera frugiperda [J.E. Smith]; tomato leaf miner, Tuta absoluta [Meyrick]).

Anthropogenic changes in crop and pest management practices such as introduction of a susceptible crop/cultivar, monocropping, and irrational use of broad-spectrum pesticides, among others, also often result in disruption of natural control, leading to outbreaks of pest and diseases. Asynchrony in range expansion of pests and their natural enemies due to climate change could also disrupt the natural control. The best approach to manage such outbreaks is to either revive or establish natural control as much as possible. Biological control primarily focuses on restoring the natural control. Biological control, as defined by Paul DeBach (1964), is the action of living organisms (parasites, predators, or pathogens) introduced by human intervention for regulating the population of another organism at densities less than those that would occur in their absence. Parasitoids are biological agents for which at least one of their life stages is intimately associated with specific life stages of the pest and with greater levels of specificity (e.g., parasitoid species belonging to Trichogramma and Telenomus parasitizing eggs of insects including FAW). The larvae of parasitoids always kill their host as the outcome of their development. Predators, on the other hand, are never intimately associated with the insect pest, and the pest serves as prey for the predator often with less specificity (e.g., insects such as ladybird beetles, earwigs, and sapsucking insects such as Orius and Podisus prey on various life stages of FAW).

Entomopathogens include bacteria, fungi, protozoans, nematodes, or viruses that infects and causes diseases in insects (e.g., fungi such as Metarhizium anisopliae and Beauveria bassiana; viruses such as Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV); and bacteria such as Bacillus thuringiensis (Bt), and others that are known to infect FAW).

Based on how biological control is undertaken, it can be broadly classified as classical (inoculative) biological control, augmentation (inundative) biological control, and conservation biological control. Classical (inoculative) biocontrol is often undertaken to 15

counter invasive pests; in this method, an exotic species of natural enemies from the region where the insect pest originated and with high level of host specificity is imported and released in the invaded regions. A successful classical biological control results in extensive, continuous, and widespread control of the invasive species (e.g., release of Cotesia flavipes for the control of Asian stem borer Chilo partellus in Africa). Prior to invasion in Africa, FAW has been prevalent in the Nearctic and Neotropical regions of America for several centuries, associated with several natural enemies. Some of these natural enemies could be potential candidates for classical biological control initiatives in Africa. An augmentation (inundative) biological control approach involves periodic releases of natural enemies or pathogens, which are either introduced or endemic, to foster biological control or to induce epizootics of pathogens against either invasive or endemic pests. In contrast to the first two forms, conservation biological control involves the manipulation of environment, cropping systems, and practices in a way that favours the natural enemies against the pest. During the process of invasion, invasive species are likely to encounter natural enemies of other species closely related to it. Some of these natural enemies could adapt to the invasive pest, often referred to as “new associations.” It is important to understand that prior to the invasion of FAW, Africa has been home to several lepidopteran pests belonging to the genus Spodoptera.

African armyworm (Spodoptera exempta Walker), beet armyworm (Spodoptera exigua Hübner), and African cotton leafworm (Spodoptera littoralis Boisduval) are among the most widely prevalent species with effective natural enemies and entomopathogens enhancing the probability of new associations to establish against FAW. The use of a biocontrol method to control a pest species does not normally affect the performance of other biological agents important in regulating pest populations, although in some cases there is intraguild predation.

Conservation Conservation of the diversity and density of natural enemies should be a key focus in such a strategy. A simple way to achieve this is to provide, near the maize area, conditions conducive to survival of natural control agents. Planting crops that provide shelter, alternative food sources, and conditions for multiplication of beneficial species may be key to regulating the FAW population. At the edges of maize cultivation areas, rows of crops such as Mexican sunflower or Crotalaria might be suitable components in landscape management with the goal of increasing the biodiversity of beneficial insects, even those that are not yet associated with FAW. A “Push-Pull” strategy can also be used, in which pest-repellent plant species are intercropped with the main crop to repel (“push”) pests out of the field, which is also

16

surrounded by a border of a pest-attractive species to “pull� both the pest and beneficial insects into it (http://www.push-pull.net). The second step in the implementation of a biocontrol-based IPM strategy against FAW is to assess the economic injury levels (EIL); strengthen monitoring, scouting, and surveillance efforts; and undertake pest management efforts through inundative release of natural enemies or through application of biorational pesticides, such as botanicals, or biopesticides, especially when the pest density exceeds EIL. Advantages of Using Biological Control of FAW in Africa The smallholder-based maize-production systems in Africa are diverse especially in terms of size, mixed cropping, seasonality, and other characteristics, unlike the large-scale commercial monocropping systems of the Americas. Further, levels of pesticide sprays on maize at present are much lower in Africa than in the other parts of the world. These are ideal conditions for effective conservation of natural enemies and achieving the full benefits of biological control (Herren and Neuenschwander 1991; Macharia et al. 2005; Soul-kifouly et al. 2016). Biological control, especially classical and conservation biological control, is much cheaper and benefits smallholder production systems in Africa. Further there are no cases of resistance development among FAW to biological control agents. With effective capacity building initiatives, Africa can take advantage of the available manpower, such as farmers’ associations, to mass-produce and release biological control agents for FAW management in Africa, as with the biological control of millet head miner in Niger and Senegal. Hence, based on the global experience of managing maize pests, biocontrol will serve as a necessary pillar of the IPM strategy for control of FAW in Africa. However, to harness this potential, it is important to assess the diversity and effectiveness of biocontrol species on the continent to identify new associations. Further, taking stock of the diversity of FAW biological control agents in America, selection of appropriate candidate agents for classical biological control of FAW in Africa based on ecological suitability assessments needs to be undertaken. Effective biorational pesticides that can aid in the management of FAW and conservation of natural enemies need to be identified and promoted. Preliminary assessments of biocontrol species on the continent suggest we should optimize the role of biocontrol in helping to manage FAW

(IPM

Innovation

Lab

2017;

https://ipmil.oired.vt.edu/wp-

content/uploads/2017/07/MuniFAW-PPT-1.pdf).

Importance of Other Beneficial Insects in the Natural Control of FAW Considerable biodiversity of beneficial insects exists in maize fields in the Americas and the Caribbean (Molina-Ochoa et al. 2003; Cruz et al. 2009). The braconid wasp Chelonus

17

insularis Cresson is one of the key natural biological control agents (Meagher et al. 2016).

Like the egg parasitoids, Chelonus parasitizes the egg of FAW; however, the FAW eggs hatch into larvae and the parasitoid adult emerges from the FAW larva. Because Chelonus is a much larger insect than Trichogramma/Telenomus wasps, Chelonus is more competitive.

The parasitized larvae gradually reduce their food intake, consuming less than 10% of the biomass consumed by a healthy larva (Rezende et al. 1994). Therefore, the presence of small larvae in the release area of Trichogramma does not necessarily mean a failure in biocontrol of FAW. Rezende et al. (1995a,b) provide further information on the role of Chelonus in IPM. In addition to C. insularis, several other parasitoid species are also considered important in suppressing populations of FAW larvae (Figueiredo et al. 2009). For example, Campoletis flavicincta has been extensively used (Matrangolo et al. 2007; Matos Neto et al. 2004). So far in Africa, Charops ater SzĂŠpligeti (Ichneumonidae), Chelonus curvimaculatus Cameron, C. maudae Huddleston, Coccygidium luteum (BrullĂŠ) (Braconidae), and Telenomus spp.

(Platygastridae) are egg and larval parasitoids found to be associated with S. frugiperda in East and West Africa (Mohamed et al. unpublished data; Goergen, unpublished data).

Standardization of mass-rearing protocols of these parasitoids on S. frugiperda and assessment of their efficiency are ongoing. In addition to the benefits of parasitoids, the presence of insect predators of both eggs and larvae is important to keep the FAW population below the economic threshold level. For example, the predatory earwig Doru luteipes (Scudder) lays its eggs inside the maize whorl, the preferred location of FAW (Reis et al.

1988), and occurs throughout the maize crop cycle. Nymphs of D. luteipes consume 8–12 larvae daily, while in the adult stage they consume 10-21 larvae of S. frugiperda daily (Reis et al. 1988). Artificial diets for rearing of D. luteipes based on insect pupa flour and pollen were found to be equal to FAW eggs (Pasini et al. 2007). Several species of earwigs are also frequently observed in the whorl and ears of maize in Africa. Earwigs are frequently assessed as predators of stemborers and aphids in maize in Africa. Among them, Diaperasticus erythrocephalus (Olivier) is frequently observed. The predatory potential of these earwigs on FAW eggs and larvae needs to be assessed in detail. Laboratory and field studies with other identified beneficial insects associated with maize pests demonstrate the real possibility of having a sustainable management of maize pests based on biocontrol strategies. 66 Chapter 5.

Biological Control and Biorational Pesticides for Fall Armyworm Management In situations where the presence of biocontrol agents is not yet at the optimal level and where pesticide applications might be required, use of microorganisms such as Baculovirus or Bacillus

18

thuringiensis should be considered (Valicente and Cruz 1991; Cruz 2000; Cruz et al. 2002; Figueiredo et al. 2009).

Biological control in India: Naturally existing enemies act as bio control agents. Parasitoids come under this category. These parasitoids lay eggs on egg masses, larvae or adult of FAW which destroys the host by growing on them.

Parasitoid

Nature

Telenomus remus Nixon

Females are egg parasitoids

Chelonus insularis Cresson

Females are ovo-larval parasitoid

Cotesia marginiventris Cresson

Females are solitary larval parasitoid

Trichogramma spp.

Females are egg parasitoids

Archytas, Winthemia and Lespesia

Females lay egg on adult

Ladybird beetles

Phytophagous in nature

Calosoma granulatum

Feeds on young cater piller

•

Entomopathogens : Generally pathogens like bacteria, fungi and virus affect the yield

of the crop. But some microorganisms are beneficial to farmers. In this NPV’s come first especially Spodoptera Frugiperda Multicapsid Nucleopolyhedrovirus (SfMNPV). Some fungi include Metarhizium anisopliae, Metarhizium rileyi, Beauveria bassiana, bacteria such as Bacillus thuringiensis (Bt).

•

Biopesticides : Bio pesticides are the pesticides that are biological in origin. Generally

the formulations are derived from specific strains of bacteria, fungi or virus. For FAW Beauveria bassiana strain R444, Bacillus thuringiensis subspecies kurstaki strain SA11, Baculovirus, SFMNPV - Baculovírus Spodoptera frugiperda are found effective.

Entomopathogens Viruses Among the microbial control agents, virus-based insecticides, which are mostly in the Baculovirus group, have been identified as having the highest potential for development as bioinsecticides due to specificity, high host virulence, and the highest safety to vertebrates (Moscardi 1999; Barrera et al. 2011). Two types of Baculovirus have been studied for the control of S. frugiperda, namely granulovirus (SfGV) (Betabaculovirus) and multiple nucleopolyhedrovirus (SfMNPV) (Alphabaculovirus). However, SfMNPV has greater

19

potential for use in the management of FAW (Behle and Popham 2012; Gómez et al. 2013; Haase et al. 2015). SfMNPV is specific to only FAW larvae. Under natural conditions, the pest is infected orally by ingesting the contaminated food (maize leaf). Once ingested, the polyhedral inclusion bodies (PIB) dissolve in the alkaline midgut, releasing the infective virions. These virions infect the midgut epithelium cells and multiply in the nucleus. Further, the virus spreads to the body cavity and infects other tissues such adipose tissue, epidermal, tracheal matrix and even salivary glands, Malpighian tube, and blood cells, causing its death from 6 to 8 days after ingestion. A caterpillar infected with the nucleopolyhedrovirus eats only 7% of the food normally eaten by a healthy caterpillar (Valicente 1988). The symptoms of Baculovirus infection include appearance of blemishes, yellowing of the skin, and decline in feeding. An infected larva moves to the higher parts of the plant and upon death hangs head down, with some prolegs still attached to the plant. The dead larvae are soft, dark in color, and disintegrate easily to release the body fluids rich in polyhedrons which aids in further spread of the virus.

Age of FAW larva at infection, amount of virus ingested, virulence of the virus, and prevailing climatic conditions, especially temperature, humidity, and solar radiation, are key factors that influence the efficacy of the virus and speed of kill. Therefore, these factors have marked effects on the virus action when it is applied in the field. In addition, other factors such as type of spray equipment, formulation used, and time of spray also influence the efficacy of the virus (Hamm and Shapiro 1992; Cisneros et al. 2002).

Better efficiency of Baculovirus for the control of FAW is obtained when applied on maize plants at the 6- to 8-leaf stage or 8- to 10-leaf stage with a costal-manual sprayer, using a wettable powder formulation containing the recommended dose of the product (2.5×1011 PIB / ha) on newly hatched larvae, applied at one time or at intervals of one week.

Fall Armyworm in Africa: A Guide for Integrated Pest Management seven days after virus application indicated a minimum larval mortality from 79.2 to 97.2%.

In a second evaluation, carried out three days after the second virus application, mortality varied from 86.6 to 100%. Viral efficiency did not vary between the two stages of plant growth. A commercial formulation for FAW NPV, SPOBIOL (prepared by CORPOICA, the Colombian public-private ag research partnership) is available and has been licensed from Certis LLC, a U.S. company.

It should be considered also that, as the caterpillar develops, it becomes more resistant to virus. Therefore, the newer the larvae, the higher the efficiency of the virus. Hence, it is 20

recommended to apply Baculovirus to larvae of a maximum of 1.5-cm long. Spraying is performed with the same equipment used for the application of a conventional chemical.

Particularly for FAW, it is recommended to use a fan nozzle (8004 or 6504). The more uniform the planting, the more efficient the application with backpack or motorized sprayers.

Appropriate nozzles to facilitate uniform application with the type or sprayer used need to be considered. Improved formulations of SfMNPV with maize flour and 1% boric acid (Cisneros et al. 2002) and microencapsulation (Gómez et al. 2013) are effective for the control of FAW. Despite various developments in terms of in vitro multiplication of baculoviruses, large-scale production of baculoviruses as a commercial biopesticide has been based on in vivo multiplication in the host insects due to the significantly low cost involved and less technology-intensive nature of production. Factors such as the ability to maintain a diseased colony of the host insect, age of the caterpillar when exposed to the pathogen, temperature at which the infected colony is maintained, concentration of virus inoculum used, nutritional profile of the larval diet, and mechanization/availability of labour are some of the critical factors that govern the efficiency of Baculovirus production (Moscardi 1999; Subramanian et al. 2006; Moscardi et al. 2011; Paiva 2013). The cannibalistic nature of FAW further adds to the complexity of SfMNPV production. Inoculation of 8-day-old larva with 1×107 PIB/ml and maintained at 25°C has been reported to be optimal to maximize the yield of SfMNPV. The cost of the biopesticide product produced is largely dependent on the cost of maintaining a disease-free colony. Use of natural diets such as castor leaves for rearing SfMNPV can greatly reduce the cost of production; however, such a system is largely prone to contamination due to extraneous virus/microsporidians. In situ field-level production using infection

of

field-collected

larva

has

been

developed

for

Spodoptera

exempta

nucleopolyhedrovirus (SpexNPV) in Tanzania, Africa. Early outbreaks of the African armyworm are sprayed with potent SpexNPV. Diseased insects are harvested, formulated using a kaolin formulation, and used for treatment of subsequent outbreaks (Mushobozi et al.

2006).

Entomopathogenic Fungi Entomopathogenic fungi (EPF) have a broad spectrum of action with the ability to infect several species of insects and different stages, causing epizootics under natural conditions (Alves et al. 2008). The fungus spores infect through the integument, multiply in various tissues within the insect body, and kill the insect due to destruction of tissues and by production of toxins. Induction of epizootics depends on climatic factors such as wind, rain,

21

or frequency of contact among the insects. Diseased insects stop feeding, become discolored (cream, green, reddish, or brown), and ultimately die as a hard-calcareous cadaver from which the fungus sporulates. Moisture is essential to the success of fungi as a biological control agent. Beauveria bassiana, Metarhizium anisopliae, and Nomuraea rileyi are the common fungi with potential uses against insect pests.

Beauveria bassiana has been used in the control of Spodoptera (e.g., Fargues and Maniania 1992). Compared to other lepidopteran pests, FAW larvae seem to be least susceptible to Beauveria bassiana (Wraight et al. 2010). Several fungal isolates belonging to three different genera (Metarhizium, Beauveria, and Isaria) have been screened for efficacy against secondinstar larvae of S. frugiperda at ICIPE, but only one isolate of B. bassiana was able to cause moderate mortality of 30% (Akutse et al. unpublished data). Current efforts are underway to screen EPF isolates for efficacy against other life stages of FAW such as adults and eggs.

Bacteria Among the various biopesticides used for insect control, Bacillus thuringiensis (Bt) Berliner biopesticides are the most widely used. These are ubiquitous, soil-dwelling, gram-positive bacteria that produce crystal proteins named delta-endotoxins, which are insecticidal. These endotoxins have relative levels of specificity to specific groups of insects. Although there are several commercial Bt products available in the market for management of lepidopteran pests, only a few are effective in controlling FAW. Among the various strains of Bt, FAW is more susceptible to Bt aizawai and Bt thuringiensis (Polanczyk et al. 2000), and not to Bt kurstaki, which is effective against many other lepidopteran pests (Silva et al. 2004). Further aspects such as the susceptibility of the endotoxin to UV, inability to reach the pest and induce consumption of the toxins, and high cost of production limit their wide adoption and use. Efforts to screen for effective Bt strains against FAW has been ongoing by several research groups. Variations among populations of FAW in their susceptibility to different Cry toxins have also been observed (Monnerat et al. 2006), which needs to be considered during the choice of Bt-based biopesticides for FAW management in different regions. With the objective of development of Bt-based biopesticides from Africa, 19 Bt strains have been screened against second-instar larvae of FAW at ICIPE. Seven Bt strains were recorded highly effective, causing 100% mortality 7 days posttreatment, with lethal time mortality (LT50) values ranging between 2.33±0.33 and 6.50±0.76 days (Akutse et al., unpublished data). Further biological and molecular characterization of these isolates are currently ongoing. Mass production of Bt-based biopesticides has been undertaken using fermentation

22

technology, either as liquid or semi-solid or solid-state fermentation (Fontana Capalbo et al.

2001). Apart from the Cry toxins, FAW is also susceptible to some of the vegetative insecticidal proteins found in the Bt culture supernatants (Barreto et al. 1999). Commercial Bt biopesticides based on strain Bt aizawai are registered and available to a limited extent in Africa. Efficacy of these biopesticides against FAW in Africa needs to be assessed.

Entomopathogenic Nematodes One of the less explored but promising strategies in biological control is the use of entomopathogenic

nematodes

(EPNs),

especially

Heterorhabditis

bacteriophora,

Heterorhabditis indica and Steinernema carpocapsae. These have proved to be human- and eco-friendly alternatives to chemical pesticides in controlling many soil-dwelling insect pests including armyworms. It is reported that FAW is very susceptible to these beneficial nematodes at the rate of 23,000 nematodes per sq. ft., to target both young and mature larvae.

Beneficial nematodes need to be applied early in the morning or late at night when armyworm larvae are very active and can be easily found by the nematodes. Another advantage of applying nematodes during these timings is the low exposure of the nematodes to UV as they can die instantly if exposed to UV light (Shapiro-Ilan et al. 2006).

Similarly, Garcia et al. (2008) reported that 280 infective juveniles of Steinernema sp. were required to kill 100% of third-instar FAW in petri dishes, as compared to 400 infective juveniles of the H. indica nematode to obtain 75% FAW control. It is possible to spray EPNs without significant loss in their concentration and viability, with equipment that produces electrical charges to the spraying mix, and with those using hydraulic and rotary nozzle tips.

The concentrations of infective juveniles of H. indica and Steinernema sp. nematodes were reduced by 28% and 53%, respectively, when hydraulic spraying nozzles that require 100mesh filtrating elements were used. Furthermore, Molina-Ochoa et al. (1999) reported earlier that Steinernema carpocapsae and S. riobravis are very effective in controlling FAW prepupae. The authors demonstrated that the combination of EPNs and resistant maize silks could enhance the mortality of FAW prepupae and could be used for integrated management of this pest. Negrisoli et al. (2010a) reported that several commercial insecticides were compatible with the three species of EPNs including Heterorhabditis indica, Steinernema carpocapsae and Steinernema glaseri under laboratory conditions. It was also reported that the efficacy of H. indica was enhanced against FAW when mixed with an insecticide, Lufenuron (Negrisoli et al. 2010b). However, it is critical to study and evaluate the

23

compatibility of insecticides, including biopesticides and EPNs, before recommending their use in an IPM program for FAW. Biological Control and Biorational Pesticides for Fall Armyworm Management • For greater efficiency of the parasitoid, the reduction or elimination of the use of chemical insecticides is necessary. If pesticide application is required, select less-toxic products and continue releasing the parasitoids two or three days later, increasing dose and frequency, to restore biological balance. • The integration of releases with other cultural, microbiological, physical, and mechanical measures may increase the overall efficiency of control.

24

Chapter-4

Integrated pest management for Fall army worm Dr. Hafeez Ahmad Professor Division of Entomology, Faculty of Agriculture, Sher-e-Kashmir University of Agricultural Sciences & Technology of Jammu, Chatha, Jammu-180009, J&K, India email:hafeezskuastj786@gmail.com __________________________________________________________________________

Spodoptera frugiperda is found widely throughout the warmer parts of the New World.

Damage results from leaf-eating and healthy plants usually recover quite quickly, but a large pest population can cause defoliation and resulting yield losses; the larvae then migrate to adjacent areas in true armyworm fashion. In the absence of natural biological control, fall armyworm can cause significant yield loss in maize and other crops.

There are many variables to consider in determining the potential yield loss due to fall armyworm infestation. In general, how the crop responds to fall armyworm infestation is highly dependent on the population level of the pest and the timing of infestation, natural enemies and pathogen levels that can help to naturally regulate the populations, and the health and vigour of the maize plant (nutritional and moisture status). Baudron et al.

(2019) have reported maize infestation of between 26.4 and 55.9% and impact on yield of 11.57%. Other authors have reported leaf, silk and tassel damage levels ranging between 25 and 50% and grain yield decrease of 58% (Chimweta et al., 2019). In Nicaragua, van Huis (1981) found a 33% increase in maize yield when plants were protected with insecticide.

Infestations during the mid- to late-whorl stage of maize development caused yield losses of 15-73% when 55-100% of the plants were infested with S. frugiperda (Hruska and Gould, 1997). Caterpillars of S. frugiperda appear to be much more damaging to maize in West and Central Africa than most other African Spodoptera species (IITA, 2016).

Monitoring of S. frugiperda Detection and Inspection Detection is facilitated by scouting fields for leaf feeding damage and by installing the pheromone traps for early detection, mass trapping and mating disruption mechanism.

25

Management strategies of Fall Armyworm (FAW), Spodoptera frugiperda on maize Monitoring: Installation of pheromone traps @5/acre in the current and potential area of spread in crop season and off-season.

Scouting: Start scouting as soon as maize seedlings emerge.

1.

At seedling to early whorl stage (3-4 weeks after emergence). Action can be taken if 5% plants are damaged.

2.

At Mid whorl to late whorl stage (5-7 weeks after emergence). Action can be taken if 10% whorls are freshly damaged in mid whorl stage and 20% whorl damage in late whorl stage.

3.

At tasseling and post tasseling (Silking stage).

Do not spray insecticides.

(No

insecticide application). But 10% ear damage needs action.

Cultural Measures: 1.

Deep ploughing is recommended before sowing.

This will expose FAW pupae to

predators.

2.

Timely sowing is advised. Avoid staggered sowings.

3.

Intercropping of maize with suitable pulse crops of particular region (e.g Maize/ pigeon pea/black gram/green gram).

4.

Erection of bird perches @ 10/acre during early stage of the crop (up to 30 days).

5.

Sowing of 3-4 rows of trap crops (e.g. Napier) around maize field and spray with 5% NSKE or azadirachtin 1500 ppm as soon as the trap crop shows symptom of FAW damage.

6.

Clean cultivation and balanced use of fertilizers.

7.

Cultivation of maize hybrids with tight husk cover will reduce ear damage by FAW.

8.

Application of Sand + lime in 9:1 ration in whorls in first thirty days of sowing.

Mechanical control: 1.

Hand picking and destruction of egg masses and neonate larvae in mass by crushing or immersing in kerosene water.

2.

Application of dry sand in to the whorl of affected maize plants soon after observation of FAW incidence in the field.

3.

Mass trapping of male moths using pheromone traps @ 15/acre.

26

Bio-Control: 1.

In situ protection of natural enemies by habitat management. Increase the plant diversity by intercropping with pulses and ornamental flowering plants which help in build-up of natural enemies.

2.

Augmentative release of Trichogramma pretiosum or Telenomus remus @ 50,000 per acre at weekly intervals or based on trap catch of 3 moths trap.

3.

Biopesticides: Suitable at 5% damage in seedling to early whorl stage and 10% ear damage with entomopathogenic fungi and bacteria.

a.

Entomopathogenic fungal formulations:

Application of Metarhizium anisopliae talc

formulation (1x108cfu/g) @ 5g/litre whorl application at 15-25 days after sowing.

Another 1-2 sprays may also be given at an interval of 10 days depending on pest damage or Metarhizium rileyi rice grain formulation (1x108cfu/g)@ 3g/litre whorl application at 15-25 days after sowing. Another 1-2 sprays may also be given at an interval of 10 days depending on pest damage. b.

Bacillus thuringiensis var. kurstaki formulations @ 2g/l (or) 400 g/acre.

Chemical Control: 1.

Seed treatment: Chemicals for seed treatment are under consideration of the Registration Committee and will be conveyed after approval of the Registration Committee.

2.

First Window (seedling to early whorl stage): To control FAW larvae at 5% damage to reduce hatchability of freshly laid eggs, spray 5% NSKE/Azadirachtin 1500 ppm @5m/l of water.

3.

Second window (mid whorl to late whorl stage): To manage 2nd and 3rd instars larvae at 10-20% damage spray Emamectin benzoate @ 0.4 g/l of water or Spinosad @ 0.3 ml/l of water or Thiamethoxam 12.6% + lambdacyhalothrin 9.5 %@ 0.5 ml/l of water or Chlorantraniliprole 18.5% SC @ 0.4 ml/l of water.

4.

Third window (8 weeks after emergence to tasseling and post tasseling): Insecticide management is not cost effective at this stage. Hand picking of the larvae is advisable.

All the sprays should be directed towards whorl and either in the early hours of the day or in the evening time.

Capacity building and mass awareness: 1.

Application and timely plant protection measures to avoid spread of the insect from the abandoned crop.

27

2.

Creation of awareness among important stake holders through trainings/group discussions.

3.

Community based and area-wide approach for implanting management strategies.

28

Chapter-5

Feasibility of semiochemicals for the management of Fall army worm Dr. Devinder Sharma Assistant Professor Division of Entomology, Faculty of Agriculture, Sher-e-Kashmir University of Agricultural Sciences & Technology of Jammu, Chatha, Jammu-180009, J&K, India __________________________________________________________________________ Analyses of extracts of pheromone glands and of volatiles from calling female fall armyworm moths, Spodoptera frugiperda (J.E. Smith), revealed the presence of the following compounds: dodecan-1-ol acetate, (Z)-7-dodecen-1-ol acetate, 11-dodecen-1-ol acetate, (Z)9-tetradecenal, (Z)-9-tetradecen-1-ol acetate, (Z)-11-hexadecenal, and (Z)-11-hexadecen-1-ol acetate. The volatiles emitted by calling females differed from the gland extract in that the two aldehydes were absent. Field tests were conducted with sticky traps baited with rubber septa formulated to release blends with the same component ratios as those emitted by calling females. These tests demonstrated that both (Z)-7-dodecen-1-ol acetate and (Z)-9-tetradecen1-ol acetate are required for optimum activity and that this blend is a significantly better lure than either virgin females or 25 mg of (Z)-9-dodecen-1-ol acetate in a polyethylene vial, the previously used standard. Addition of the other three acetates found in the volatiles did not significantly increase the effectiveness of the two-component blend as a bait for Pherocon 1C or International Pheromones moth traps.

Introduction Chemical communication plays an important and essential role in the survival of insects, which enable them to appraise immediate environment through modification of their behavior. Semiochemicals are organic compounds used by insects to convey specific chemical messages that modify behavior or physiology [1]. The term semiochemical is derived from the Greek word “semeon� which means sign or signal. Insects use semiochemicals to locate mate, host, or food source, avoid competition, escape natural enemies, and overcome natural defense systems of their hosts. Semiochemicals have the advantage of being used to communicate message over relatively long distances compared with other insect means of communication such as touch. Semiochemicals have different

29

molecular weights depending on carbon chain. They are biologically active at very low concentration in the environment, thus their chemical characterization is complicated.

Fall armyworm (FAW), Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae), is native to tropical and subtropical regions of the Americas and is the key insect pest of maize in tropical regions. The genus Spodoptera includes several insect species that cause substantial damage to agricultural crops throughout the world. Three species, S. exigua (Hfibner), S. frugiperda (J.E. Smith), and S. eridania (Cramer), are serious pests of many crops in the United States. The fall armyworm (FAW), S. frugiperda, is an important pest of corn and other grass crops throughout the world, where it is known as the whorl- worm, and attacks a variety of crops (Andrews, 1980). FAW is a highly polyphagous insect pest that attacks more than 80 plant species, including maize, sorghum, millet, sugarcane, and vegetable crops [4]; nevertheless, maize is the main crop affected by FAW. According to a recent estimate, in the absence of control methods, FAW has the potential to cause losses of an estimated 8.3 to 20.6 m tons of maize per annum (valued at US$2481–6187 m) in 12 maize-producing countries in SSA, which accounts for approximately 20% of the total production in the region. FAW larvae cause damage to the plant by consuming foliage.

Young larvae mainly feed on epidermal leaf tissue and also make holes in leaves, which is the typical damage symptom of FAW. Feeding on young plants through the whorl causes deadheart. In older plants, the larger larvae in the whorls can feed on maize cob or kernels, reducing yield and quality. As is common with other major agricultural pests, the primary management strategy for FAW in the Americas is the use of synthetic insecticide sprays and genetically modiďŹ ed crops (Bt maize). Nevertheless, FAW has developed resistance to several synthetic insecticides for example, according to Abrahams et al., actioncategories1A (Carbamates) 1B (Organophosphates), and 3A (Pyrethroids-Pyrethrins). Furthermore, FAW resistance to Bt maize has been reported in different regions such as Puerto Rico, Brazil, Argentina, and the southeastern mainland USA. This suggests the need for an integrated management strategy for the sustainable control of this invasive pest.

Components of the FAW pheromone have been identified in previous investigations.

Sekul and Sparks (1967) used a laboratory bioassay in which a mating response was evoked in FAW males to monitor the isolation and identification of a sex pheromone, (Z)-9tetradecen-l-ol acetate (Z9-14: Ac), from FAW females. Subsequent tests showed this compound to be an ineffective lure for FAW males in the field (Mitchell and Doolittle, 1976; Sparks, 1980). However, this compound did reduce mating by FAWs when it was evaporated

30

into the atmosphere in disruption tests (Mitchell and McLaughlin, 1982). A second compound, (Z)-9-dodecen- 1-ol acetate (Z9-12 : Ac), was isolated and identified from FAW females (Sekul and Sparks, 1976), and this compound either alone or with small quantities of Z9-14:Ac added is a good practical lure for fall armyworm males when used in sticky traps (Mitchell, 1978; Jones and Sparks, 1979). However, fairly large quantities of Z9-12 :Ac are required for effectiveness (5-10 mg on a rubber septum), and the baits are effective in the field for only one to two weeks (Mitchell et al., 1983). Sparks (1980) reported that two additional compounds had been identified from washes of FAW female ovipositors, but he did not give their identity and he stated that they did not improve the effectiveness of Z912:Ac as a lure. Descoins and coworkers (personal communication) analyzed the FAW female-produced pheromone and found (Z)-ll-hexadecen-l-ol acetate (Zll- 16 : Ac), in addition to the two compounds already reported. However, in field tests conducted in Florida, we could not find a blend of these three compounds that was significantly better than Z9-12 : Ac alone in luring FAW males to sticky traps (Mitchell et al., 1983).

Potential use of semiochemicals in insect pest management Semiochemicals have been used for insect pest management more than 100 years ago.

Insect sex pheromones are the semiochemicals that are widely used for the management of insect pest particularly members of the order Lepidoptera. Aggregation pheromones from the order Coleoptera are also used for the management of agricultural insect pests of economic importance. Several serious agricultural pests including the carob moth Ectomyelois ceratoniae, the armyworm Spodoptera frugiperda, tomato leaf miner Tuta absoluta, fruit flies Bactrocera sp., mountain pine beetle (MPB) Dendroctonus ponderosae, Asian citrus psyllid Diaphorina citri, and the red palm weevil (RPW) Rhynchophorus ferrugineus, FAW (Fall army worm) have been successfully managed by using semiochemicals. Semiochemicals are considered safe and environmentally friendly molecules due to their natural origin, low persistency in the environment, and species specificity, which attribute much to their harmless effect on non-target organisms. However, there are some difficulties in the practical applications of semiochemicals in pest management, and due to these challenges Semiochemically-based pest methods are still at the beginning. Baker mentioned the reasons that promoted or hindered the adoption of pheromones in the management programs of insect species as follows: •

The biological differences in the mate-finding behavior of different species.

•

The chemistries of the pheromones used.

31

•

The successful engineering of the controlled-release dispenser and the use of proper trap design

•

The different political, economic, and use-pattern in different countries particularly the regulation of pheromones’ application.

32

Chapter-2

Bio-ecology of Fall army worm Dr. Amit Kumar Singh Associate Professor Division of Entomology, Faculty of Agriculture, Sher-e-Kashmir University of Agricultural Sciences & Technology of Jammu, Chatha, Jammu-180009, J&K, India email: __________________________________________________________________________ The fall armyworm, Spodoptera frugiperda (J. E. Smith), has been classified as a sporadic pest due to its migratory behavior. This species does not enter diapause, so it migrates from warmer climates such as southern Florida, Caribbean Islands, southern Texas, Mexico, and coastal areas of southern Georgia, Alabama, Mississippi, and Louisiana, northward across the United States annually (Luginbill 1928, Sparks 1979, Knipling 1980, Ashley et al. 1989, Adamczyk 1998). Fall armyworm movement each year generally creates sporadic problems across multiple crops, including maize (Zea mays L.). Fall armyworm outbreaks and subsequent damage can be unpredictable. When outbreaks do occur, the severity of the problem is compounded by the ability of fall armyworm to damage a range of vegetative to reproductive plant structures, creating the opportunity to cause devastating crop losses.

Biology of armyworm (Spodoptera frugiperda) Fall armyworm can be one of the more difficult insect pests to control in field maize/corn.

Late planted fields and later maturing hybrids are more likely to become infested. It causes serious leaf feeding damage as well as direct injury to the ear. While fall armyworms can damage corn plants in nearly all stages of development, it will concentrate on later plantings that have not yet silked. Like European corn borer, fall armyworm can only be effectively controlled while the larvae are small. Early detection and proper timing of an insecticide application are critical.

The fall armyworm has several generations per year, with the life cycle consisting of egg, six to seven larval instars, pupa, and adult.

Adult FAW Moth As moths emerge from the soil, they can mate locally or migrate up to 300 miles before mating and ovipositing (Ashley et al., 1989).

10

Eggs are generally laid on the abaxial (underside) surface of leaves; however, when oviposition frequency in a cotton field is high, females will oviposit eggs on all plant structures (Luginbill 1928, Sparks 1979, Ali 1989). The most preferred location for oviposition is on leaves emerging directly from the main stem in the middle to lower portion of the plant canopy (Ali 1989). The spherical gray eggs are laid in clusters 50 to 150, usually on the leaves. Egg masses are covered with a coating of moth scales or fine bristles. Larvae hatch in 3 to 5 days and move to the whorl.

FAW Larva Upon eclosion, neonates consume the egg mass from which they hatched. Larvae then disperse in all directions, beginning to feed on vegetative tissue. Later instars prefer to feed on reproductive structures such as squares (flower buds) and bolls. Larval feeding and adult activity most frequently occurs at night, but can occur in late evening and early morning. Number of instars can range from six to seven depending on environmental conditions and availability of food.

The final instar will consume a greater quantity of food than all previous instars combined (Luginbill, 1928). The length of time for larval development (hatching to pupation) varies based on temperature and environmental conditions, but can range from 11 to 50 d (Luginbill 1928; Hogg et al., 1982). At 25°C larval development on cotton takes 22 days (Pitre and Hogg 1983). Fall armyworm larva vary from light tan to black with three light yellow stripes down the back. There is a wider dark stripe and a wavy yellow-red blotched stripe on each side. Larvae have four pairs of fleshy abdominal prolegs in addition to the pair at the end of the body.Fall armyworm resembles both armyworm and corn earworm, but fall armyworm has a white inverted "Y" mark on the front of the dark head.

The corn earworm has a orange-brown head, while the armyworm has a brown head with dark honeycombed markings. Fall armyworm has four dark spots arranged in a square on top of the eighth abdominal segment.

Larvae fall from the plant and burrow into soil to a depth of one to three inches in the soil, remain in a pre pupal state for 2–4 d, and pupate there for 7–10 d (Luginbill, 1928; Pitre and

11

Hogg, 1983). Depth of pupation is dependent upon factors such as soil texture, soil moisture, and soil temperature (Sparks, 1979).

FAW Damage Very early symptoms of fall armyworm resemble European corn borer infestation. Small holes and "window pane" feeding in the leaves emerging from the whorl are common.

Although initial symptoms of damage are similar, thresholds and control measures differ.

Therefore it is important to find the live larvae and determine which insect is causing the damage. Unlike armyworm, fall armyworm feeds during the day and night, but are usually most active in the morning or late afternoon.

The most common damage is to late pretassel corn. Larger fall armyworm larvae consume large amounts of leaf tissue resulting in a ragged appearance to the leaves similar to grasshopper damage. Larger larvae are usually found deep in the whorl often below a "plug" of yellowish brown frass. Beneath this plug, larvae are protected somewhat from insecticide applications. Plants often recover from whorl damage without any reduction in yield.

Larvae will also move to the ear as plants begin to tassel and young ears become available.

The ear may be partly or totally destroyed. Damage to the ear may be much more important than leaf damage.

A threshold temperature of 10.9째C and 559 day-degrees C is required for development.

Sandy-clay or clay-sand soils are suitable for pupation and adult emergence. Emergence in sandy-clay and clay-sand soils was directly proportional to temperature and inversely proportional to humidity. Above 30째C the wings of adults tend to be deformed. Pupae require a threshold temperature of 14.6째C and 138 day-degrees C to complete their development (Ramirez-Garcia et al., 1987).

S. frugiperda is a tropical species adapted to the warmer parts of the New World; the optimum temperature for larval development is reported to be 28째C, but it is lower for both oviposition and pupation. In the tropics, breeding can be continuous with four to six generations per year, but in northern regions only one or two generations develop; at lower temperatures, activity and development cease, and when freezing occurs all stages are usually killed.

Agro-ecological approaches to pest management: 1 Minimum soil disturbance enhances biological properties of soil, thereby improving soil fertility management and plant nutrition

12

2 Mulching of crop residues protects the soil surface and adds carbon to improve soil fertility management, and in addition provides habitat for insect predators especially spiders, earwigs, beetles and ants 3.Planting leguminous inter-crops or cover crops improves soil fertility management through nitrogen fixation, diversifies the field environment for beneficial insects, including insect predators and parasitoids, and through the production of olfactory cues can deter pests from laying eggs (also in the case of FAW, intercrops may trap the ballooning first instar larvae thereby increasing mortality) 4. Shrubs/trees with flowers or extra flora nectaries support populations of ants and small wasps 5. Boundary trees (e.g. fodder trees, fuelwood trees, shelter trees) provide perches and roosts for birds and bats and increase the structural diversity of the farm habitat through shade and shelter 6. Crop rotation – improves soil fertility management and diversifies the farm environment 7. Regular scouting by the farmer to identify pests and assess damage enables informed pest management decisions 8.Weeds allowed to grow between the maize rows and along field margin can provide habitat for insect predators and encourage parasitoids and predatory wasps through provision of nectar (however, weeds can also compete with the crop and sometimes provide alternative hosts for pests, hence detailed understanding of their effects is required) 9. Diverse field margins provide habitat for generalist predators, such as spiders, beetles, earwigs and ants 10. Insectivorous birds and bats provide an important role in reducing pest abundance in diverse agro-ecological systems 11. Nest site provision for predatory wasps or ants could be used to enhance the local abundance of insect predators 12. Predatory wasp – these wasps hunt pest caterpillars to provision their larvae. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

13

Chapter-3

Promising Biocontrol Agents for the control of fall army worm Dr. R. K. Gupta Professor Division of Entomology, Faculty of Agriculture, Sher-e-Kashmir University of Agricultural Sciences & Technology of Jammu, Chatha, Jammu-180009, J&K, India E mail: rkguptaentoskuast@gmail.com __________________________________________________________________________ Key facts •

Fall Armyworm is an insect native to tropical and subtropical regions of the Americas

•

It was first detected in Central and Western Africa in early 2016 and has now spread across Sub-Saharan Africa and recently reached Yemen and India

•

In the larval stage, the insect causes damage to crops, feeding on more than 80 plant species

•

FAW primarily affects maize, but also rice and sorghum as well as cotton and some vegetables

•

The moth can fly up to 100 km per night and the female moth can lay up to a total of 1000 eggs in her lifetime

•

In the Americas, farmers have been managing FAW in their crops for many centuries and researches have been studying it for decades

•

Sustainable management practices that are used in the Americas need to be to be adapted to countries’ socio-economic-environmental contexts

Invasion: The Fall Armyworm (FAW), Spodoptera frugiperda, was detected for the first time on the Indian subcontinent in mid-May this year in maize fields at the College of Agriculture, University of Agricultural and Horticultural Sciences (UAHS), Shivamogga, Karnataka. This was the report of IITA Scientist Georg Goergen, who provided technical assistance in tracking the pest’s identity. Following morphological identification, Drs Sharanabasappa and Kalleshwara Swamy of UAHS confirmed the pest’s identity using molecular techniques. Similar information has also just been released based on independent investigations by the National Bureau of Agriculturally Important Microorganisms (NBAIR) under the Indian Council of Agricultural Research (ICAR).

14

What are Biological and Options?

In nature, the population of any organism is regulated. It is kept fluctuating within an upper and lower threshold, often below economically damaging levels, due to the actions of biotic regulations (availability of food, parasites, predators, and/or pathogens) and/or abiotic factors (climate and soil factors). Such population regulation is referred to as natural control.

However, such natural control when disrupted due to biological, anthropogenic, or climatic factors results in the outbreak of organisms leading to economic damage. Invasiveness of a pest species into new geographies in the absence of biotic regulatory factors often results in the disruption of natural control, leading to devastating outbreaks (e.g., fall armyworm (FAW), Spodoptera frugiperda [J.E. Smith]; tomato leaf miner, Tuta absoluta [Meyrick]).

Anthropogenic changes in crop and pest management practices such as introduction of a susceptible crop/cultivar, monocropping, and irrational use of broad-spectrum pesticides, among others, also often result in disruption of natural control, leading to outbreaks of pest and diseases. Asynchrony in range expansion of pests and their natural enemies due to climate change could also disrupt the natural control. The best approach to manage such outbreaks is to either revive or establish natural control as much as possible. Biological control primarily focuses on restoring the natural control. Biological control, as defined by Paul DeBach (1964), is the action of living organisms (parasites, predators, or pathogens) introduced by human intervention for regulating the population of another organism at densities less than those that would occur in their absence. Parasitoids are biological agents for which at least one of their life stages is intimately associated with specific life stages of the pest and with greater levels of specificity (e.g., parasitoid species belonging to Trichogramma and Telenomus parasitizing eggs of insects including FAW). The larvae of parasitoids always kill their host as the outcome of their development. Predators, on the other hand, are never intimately associated with the insect pest, and the pest serves as prey for the predator often with less specificity (e.g., insects such as ladybird beetles, earwigs, and sapsucking insects such as Orius and Podisus prey on various life stages of FAW).

Entomopathogens include bacteria, fungi, protozoans, nematodes, or viruses that infects and causes diseases in insects (e.g., fungi such as Metarhizium anisopliae and Beauveria bassiana; viruses such as Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV); and bacteria such as Bacillus thuringiensis (Bt), and others that are known to infect FAW).

Based on how biological control is undertaken, it can be broadly classified as classical (inoculative) biological control, augmentation (inundative) biological control, and conservation biological control. Classical (inoculative) biocontrol is often undertaken to 15

counter invasive pests; in this method, an exotic species of natural enemies from the region where the insect pest originated and with high level of host specificity is imported and released in the invaded regions. A successful classical biological control results in extensive, continuous, and widespread control of the invasive species (e.g., release of Cotesia flavipes for the control of Asian stem borer Chilo partellus in Africa). Prior to invasion in Africa, FAW has been prevalent in the Nearctic and Neotropical regions of America for several centuries, associated with several natural enemies. Some of these natural enemies could be potential candidates for classical biological control initiatives in Africa. An augmentation (inundative) biological control approach involves periodic releases of natural enemies or pathogens, which are either introduced or endemic, to foster biological control or to induce epizootics of pathogens against either invasive or endemic pests. In contrast to the first two forms, conservation biological control involves the manipulation of environment, cropping systems, and practices in a way that favours the natural enemies against the pest. During the process of invasion, invasive species are likely to encounter natural enemies of other species closely related to it. Some of these natural enemies could adapt to the invasive pest, often referred to as “new associations.” It is important to understand that prior to the invasion of FAW, Africa has been home to several lepidopteran pests belonging to the genus Spodoptera.

African armyworm (Spodoptera exempta Walker), beet armyworm (Spodoptera exigua Hübner), and African cotton leafworm (Spodoptera littoralis Boisduval) are among the most widely prevalent species with effective natural enemies and entomopathogens enhancing the probability of new associations to establish against FAW. The use of a biocontrol method to control a pest species does not normally affect the performance of other biological agents important in regulating pest populations, although in some cases there is intraguild predation.

Conservation Conservation of the diversity and density of natural enemies should be a key focus in such a strategy. A simple way to achieve this is to provide, near the maize area, conditions conducive to survival of natural control agents. Planting crops that provide shelter, alternative food sources, and conditions for multiplication of beneficial species may be key to regulating the FAW population. At the edges of maize cultivation areas, rows of crops such as Mexican sunflower or Crotalaria might be suitable components in landscape management with the goal of increasing the biodiversity of beneficial insects, even those that are not yet associated with FAW. A “Push-Pull” strategy can also be used, in which pest-repellent plant species are intercropped with the main crop to repel (“push”) pests out of the field, which is also

16

surrounded by a border of a pest-attractive species to “pull� both the pest and beneficial insects into it (http://www.push-pull.net). The second step in the implementation of a biocontrol-based IPM strategy against FAW is to assess the economic injury levels (EIL); strengthen monitoring, scouting, and surveillance efforts; and undertake pest management efforts through inundative release of natural enemies or through application of biorational pesticides, such as botanicals, or biopesticides, especially when the pest density exceeds EIL. Advantages of Using Biological Control of FAW in Africa The smallholder-based maize-production systems in Africa are diverse especially in terms of size, mixed cropping, seasonality, and other characteristics, unlike the large-scale commercial monocropping systems of the Americas. Further, levels of pesticide sprays on maize at present are much lower in Africa than in the other parts of the world. These are ideal conditions for effective conservation of natural enemies and achieving the full benefits of biological control (Herren and Neuenschwander 1991; Macharia et al. 2005; Soul-kifouly et al. 2016). Biological control, especially classical and conservation biological control, is much cheaper and benefits smallholder production systems in Africa. Further there are no cases of resistance development among FAW to biological control agents. With effective capacity building initiatives, Africa can take advantage of the available manpower, such as farmers’ associations, to mass-produce and release biological control agents for FAW management in Africa, as with the biological control of millet head miner in Niger and Senegal. Hence, based on the global experience of managing maize pests, biocontrol will serve as a necessary pillar of the IPM strategy for control of FAW in Africa. However, to harness this potential, it is important to assess the diversity and effectiveness of biocontrol species on the continent to identify new associations. Further, taking stock of the diversity of FAW biological control agents in America, selection of appropriate candidate agents for classical biological control of FAW in Africa based on ecological suitability assessments needs to be undertaken. Effective biorational pesticides that can aid in the management of FAW and conservation of natural enemies need to be identified and promoted. Preliminary assessments of biocontrol species on the continent suggest we should optimize the role of biocontrol in helping to manage FAW

(IPM

Innovation

Lab

2017;

https://ipmil.oired.vt.edu/wp-

content/uploads/2017/07/MuniFAW-PPT-1.pdf).

Importance of Other Beneficial Insects in the Natural Control of FAW Considerable biodiversity of beneficial insects exists in maize fields in the Americas and the Caribbean (Molina-Ochoa et al. 2003; Cruz et al. 2009). The braconid wasp Chelonus

17

insularis Cresson is one of the key natural biological control agents (Meagher et al. 2016).

Like the egg parasitoids, Chelonus parasitizes the egg of FAW; however, the FAW eggs hatch into larvae and the parasitoid adult emerges from the FAW larva. Because Chelonus is a much larger insect than Trichogramma/Telenomus wasps, Chelonus is more competitive.

The parasitized larvae gradually reduce their food intake, consuming less than 10% of the biomass consumed by a healthy larva (Rezende et al. 1994). Therefore, the presence of small larvae in the release area of Trichogramma does not necessarily mean a failure in biocontrol of FAW. Rezende et al. (1995a,b) provide further information on the role of Chelonus in IPM. In addition to C. insularis, several other parasitoid species are also considered important in suppressing populations of FAW larvae (Figueiredo et al. 2009). For example, Campoletis flavicincta has been extensively used (Matrangolo et al. 2007; Matos Neto et al. 2004). So far in Africa, Charops ater SzĂŠpligeti (Ichneumonidae), Chelonus curvimaculatus Cameron, C. maudae Huddleston, Coccygidium luteum (BrullĂŠ) (Braconidae), and Telenomus spp.

(Platygastridae) are egg and larval parasitoids found to be associated with S. frugiperda in East and West Africa (Mohamed et al. unpublished data; Goergen, unpublished data).

Standardization of mass-rearing protocols of these parasitoids on S. frugiperda and assessment of their efficiency are ongoing. In addition to the benefits of parasitoids, the presence of insect predators of both eggs and larvae is important to keep the FAW population below the economic threshold level. For example, the predatory earwig Doru luteipes (Scudder) lays its eggs inside the maize whorl, the preferred location of FAW (Reis et al.

1988), and occurs throughout the maize crop cycle. Nymphs of D. luteipes consume 8–12 larvae daily, while in the adult stage they consume 10-21 larvae of S. frugiperda daily (Reis et al. 1988). Artificial diets for rearing of D. luteipes based on insect pupa flour and pollen were found to be equal to FAW eggs (Pasini et al. 2007). Several species of earwigs are also frequently observed in the whorl and ears of maize in Africa. Earwigs are frequently assessed as predators of stemborers and aphids in maize in Africa. Among them, Diaperasticus erythrocephalus (Olivier) is frequently observed. The predatory potential of these earwigs on FAW eggs and larvae needs to be assessed in detail. Laboratory and field studies with other identified beneficial insects associated with maize pests demonstrate the real possibility of having a sustainable management of maize pests based on biocontrol strategies. 66 Chapter 5.

Biological Control and Biorational Pesticides for Fall Armyworm Management In situations where the presence of biocontrol agents is not yet at the optimal level and where pesticide applications might be required, use of microorganisms such as Baculovirus or Bacillus

18

thuringiensis should be considered (Valicente and Cruz 1991; Cruz 2000; Cruz et al. 2002; Figueiredo et al. 2009).

Biological control in India: Naturally existing enemies act as bio control agents. Parasitoids come under this category. These parasitoids lay eggs on egg masses, larvae or adult of FAW which destroys the host by growing on them.

Parasitoid

Nature

Telenomus remus Nixon

Females are egg parasitoids

Chelonus insularis Cresson

Females are ovo-larval parasitoid

Cotesia marginiventris Cresson

Females are solitary larval parasitoid

Trichogramma spp.

Females are egg parasitoids

Archytas, Winthemia and Lespesia

Females lay egg on adult

Ladybird beetles

Phytophagous in nature

Calosoma granulatum

Feeds on young cater piller

•

Entomopathogens : Generally pathogens like bacteria, fungi and virus affect the yield

of the crop. But some microorganisms are beneficial to farmers. In this NPV’s come first especially Spodoptera Frugiperda Multicapsid Nucleopolyhedrovirus (SfMNPV). Some fungi include Metarhizium anisopliae, Metarhizium rileyi, Beauveria bassiana, bacteria such as Bacillus thuringiensis (Bt).

•

Biopesticides : Bio pesticides are the pesticides that are biological in origin. Generally

the formulations are derived from specific strains of bacteria, fungi or virus. For FAW Beauveria bassiana strain R444, Bacillus thuringiensis subspecies kurstaki strain SA11, Baculovirus, SFMNPV - Baculovírus Spodoptera frugiperda are found effective.

Entomopathogens Viruses Among the microbial control agents, virus-based insecticides, which are mostly in the Baculovirus group, have been identified as having the highest potential for development as bioinsecticides due to specificity, high host virulence, and the highest safety to vertebrates (Moscardi 1999; Barrera et al. 2011). Two types of Baculovirus have been studied for the control of S. frugiperda, namely granulovirus (SfGV) (Betabaculovirus) and multiple nucleopolyhedrovirus (SfMNPV) (Alphabaculovirus). However, SfMNPV has greater

19

potential for use in the management of FAW (Behle and Popham 2012; Gómez et al. 2013; Haase et al. 2015). SfMNPV is specific to only FAW larvae. Under natural conditions, the pest is infected orally by ingesting the contaminated food (maize leaf). Once ingested, the polyhedral inclusion bodies (PIB) dissolve in the alkaline midgut, releasing the infective virions. These virions infect the midgut epithelium cells and multiply in the nucleus. Further, the virus spreads to the body cavity and infects other tissues such adipose tissue, epidermal, tracheal matrix and even salivary glands, Malpighian tube, and blood cells, causing its death from 6 to 8 days after ingestion. A caterpillar infected with the nucleopolyhedrovirus eats only 7% of the food normally eaten by a healthy caterpillar (Valicente 1988). The symptoms of Baculovirus infection include appearance of blemishes, yellowing of the skin, and decline in feeding. An infected larva moves to the higher parts of the plant and upon death hangs head down, with some prolegs still attached to the plant. The dead larvae are soft, dark in color, and disintegrate easily to release the body fluids rich in polyhedrons which aids in further spread of the virus.

Age of FAW larva at infection, amount of virus ingested, virulence of the virus, and prevailing climatic conditions, especially temperature, humidity, and solar radiation, are key factors that influence the efficacy of the virus and speed of kill. Therefore, these factors have marked effects on the virus action when it is applied in the field. In addition, other factors such as type of spray equipment, formulation used, and time of spray also influence the efficacy of the virus (Hamm and Shapiro 1992; Cisneros et al. 2002).

Better efficiency of Baculovirus for the control of FAW is obtained when applied on maize plants at the 6- to 8-leaf stage or 8- to 10-leaf stage with a costal-manual sprayer, using a wettable powder formulation containing the recommended dose of the product (2.5×1011 PIB / ha) on newly hatched larvae, applied at one time or at intervals of one week.

Fall Armyworm in Africa: A Guide for Integrated Pest Management seven days after virus application indicated a minimum larval mortality from 79.2 to 97.2%.

In a second evaluation, carried out three days after the second virus application, mortality varied from 86.6 to 100%. Viral efficiency did not vary between the two stages of plant growth. A commercial formulation for FAW NPV, SPOBIOL (prepared by CORPOICA, the Colombian public-private ag research partnership) is available and has been licensed from Certis LLC, a U.S. company.

It should be considered also that, as the caterpillar develops, it becomes more resistant to virus. Therefore, the newer the larvae, the higher the efficiency of the virus. Hence, it is 20

recommended to apply Baculovirus to larvae of a maximum of 1.5-cm long. Spraying is performed with the same equipment used for the application of a conventional chemical.

Particularly for FAW, it is recommended to use a fan nozzle (8004 or 6504). The more uniform the planting, the more efficient the application with backpack or motorized sprayers.

Appropriate nozzles to facilitate uniform application with the type or sprayer used need to be considered. Improved formulations of SfMNPV with maize flour and 1% boric acid (Cisneros et al. 2002) and microencapsulation (Gómez et al. 2013) are effective for the control of FAW. Despite various developments in terms of in vitro multiplication of baculoviruses, large-scale production of baculoviruses as a commercial biopesticide has been based on in vivo multiplication in the host insects due to the significantly low cost involved and less technology-intensive nature of production. Factors such as the ability to maintain a diseased colony of the host insect, age of the caterpillar when exposed to the pathogen, temperature at which the infected colony is maintained, concentration of virus inoculum used, nutritional profile of the larval diet, and mechanization/availability of labour are some of the critical factors that govern the efficiency of Baculovirus production (Moscardi 1999; Subramanian et al. 2006; Moscardi et al. 2011; Paiva 2013). The cannibalistic nature of FAW further adds to the complexity of SfMNPV production. Inoculation of 8-day-old larva with 1×107 PIB/ml and maintained at 25°C has been reported to be optimal to maximize the yield of SfMNPV. The cost of the biopesticide product produced is largely dependent on the cost of maintaining a disease-free colony. Use of natural diets such as castor leaves for rearing SfMNPV can greatly reduce the cost of production; however, such a system is largely prone to contamination due to extraneous virus/microsporidians. In situ field-level production using infection

of

field-collected

larva

has

been

developed

for

Spodoptera

exempta

nucleopolyhedrovirus (SpexNPV) in Tanzania, Africa. Early outbreaks of the African armyworm are sprayed with potent SpexNPV. Diseased insects are harvested, formulated using a kaolin formulation, and used for treatment of subsequent outbreaks (Mushobozi et al.

2006).

Entomopathogenic Fungi Entomopathogenic fungi (EPF) have a broad spectrum of action with the ability to infect several species of insects and different stages, causing epizootics under natural conditions (Alves et al. 2008). The fungus spores infect through the integument, multiply in various tissues within the insect body, and kill the insect due to destruction of tissues and by production of toxins. Induction of epizootics depends on climatic factors such as wind, rain,

21

or frequency of contact among the insects. Diseased insects stop feeding, become discolored (cream, green, reddish, or brown), and ultimately die as a hard-calcareous cadaver from which the fungus sporulates. Moisture is essential to the success of fungi as a biological control agent. Beauveria bassiana, Metarhizium anisopliae, and Nomuraea rileyi are the common fungi with potential uses against insect pests.

Beauveria bassiana has been used in the control of Spodoptera (e.g., Fargues and Maniania 1992). Compared to other lepidopteran pests, FAW larvae seem to be least susceptible to Beauveria bassiana (Wraight et al. 2010). Several fungal isolates belonging to three different genera (Metarhizium, Beauveria, and Isaria) have been screened for efficacy against secondinstar larvae of S. frugiperda at ICIPE, but only one isolate of B. bassiana was able to cause moderate mortality of 30% (Akutse et al. unpublished data). Current efforts are underway to screen EPF isolates for efficacy against other life stages of FAW such as adults and eggs.

Bacteria Among the various biopesticides used for insect control, Bacillus thuringiensis (Bt) Berliner biopesticides are the most widely used. These are ubiquitous, soil-dwelling, gram-positive bacteria that produce crystal proteins named delta-endotoxins, which are insecticidal. These endotoxins have relative levels of specificity to specific groups of insects. Although there are several commercial Bt products available in the market for management of lepidopteran pests, only a few are effective in controlling FAW. Among the various strains of Bt, FAW is more susceptible to Bt aizawai and Bt thuringiensis (Polanczyk et al. 2000), and not to Bt kurstaki, which is effective against many other lepidopteran pests (Silva et al. 2004). Further aspects such as the susceptibility of the endotoxin to UV, inability to reach the pest and induce consumption of the toxins, and high cost of production limit their wide adoption and use. Efforts to screen for effective Bt strains against FAW has been ongoing by several research groups. Variations among populations of FAW in their susceptibility to different Cry toxins have also been observed (Monnerat et al. 2006), which needs to be considered during the choice of Bt-based biopesticides for FAW management in different regions. With the objective of development of Bt-based biopesticides from Africa, 19 Bt strains have been screened against second-instar larvae of FAW at ICIPE. Seven Bt strains were recorded highly effective, causing 100% mortality 7 days posttreatment, with lethal time mortality (LT50) values ranging between 2.33±0.33 and 6.50±0.76 days (Akutse et al., unpublished data). Further biological and molecular characterization of these isolates are currently ongoing. Mass production of Bt-based biopesticides has been undertaken using fermentation

22

technology, either as liquid or semi-solid or solid-state fermentation (Fontana Capalbo et al.

2001). Apart from the Cry toxins, FAW is also susceptible to some of the vegetative insecticidal proteins found in the Bt culture supernatants (Barreto et al. 1999). Commercial Bt biopesticides based on strain Bt aizawai are registered and available to a limited extent in Africa. Efficacy of these biopesticides against FAW in Africa needs to be assessed.

Entomopathogenic Nematodes One of the less explored but promising strategies in biological control is the use of entomopathogenic

nematodes

(EPNs),

especially

Heterorhabditis

bacteriophora,

Heterorhabditis indica and Steinernema carpocapsae. These have proved to be human- and eco-friendly alternatives to chemical pesticides in controlling many soil-dwelling insect pests including armyworms. It is reported that FAW is very susceptible to these beneficial nematodes at the rate of 23,000 nematodes per sq. ft., to target both young and mature larvae.

Beneficial nematodes need to be applied early in the morning or late at night when armyworm larvae are very active and can be easily found by the nematodes. Another advantage of applying nematodes during these timings is the low exposure of the nematodes to UV as they can die instantly if exposed to UV light (Shapiro-Ilan et al. 2006).

Similarly, Garcia et al. (2008) reported that 280 infective juveniles of Steinernema sp. were required to kill 100% of third-instar FAW in petri dishes, as compared to 400 infective juveniles of the H. indica nematode to obtain 75% FAW control. It is possible to spray EPNs without significant loss in their concentration and viability, with equipment that produces electrical charges to the spraying mix, and with those using hydraulic and rotary nozzle tips.

The concentrations of infective juveniles of H. indica and Steinernema sp. nematodes were reduced by 28% and 53%, respectively, when hydraulic spraying nozzles that require 100mesh filtrating elements were used. Furthermore, Molina-Ochoa et al. (1999) reported earlier that Steinernema carpocapsae and S. riobravis are very effective in controlling FAW prepupae. The authors demonstrated that the combination of EPNs and resistant maize silks could enhance the mortality of FAW prepupae and could be used for integrated management of this pest. Negrisoli et al. (2010a) reported that several commercial insecticides were compatible with the three species of EPNs including Heterorhabditis indica, Steinernema carpocapsae and Steinernema glaseri under laboratory conditions. It was also reported that the efficacy of H. indica was enhanced against FAW when mixed with an insecticide, Lufenuron (Negrisoli et al. 2010b). However, it is critical to study and evaluate the

23

compatibility of insecticides, including biopesticides and EPNs, before recommending their use in an IPM program for FAW. Biological Control and Biorational Pesticides for Fall Armyworm Management • For greater efficiency of the parasitoid, the reduction or elimination of the use of chemical insecticides is necessary. If pesticide application is required, select less-toxic products and continue releasing the parasitoids two or three days later, increasing dose and frequency, to restore biological balance. • The integration of releases with other cultural, microbiological, physical, and mechanical measures may increase the overall efficiency of control.

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Chapter-4

Integrated pest management for Fall army worm Dr. Hafeez Ahmad Professor Division of Entomology, Faculty of Agriculture, Sher-e-Kashmir University of Agricultural Sciences & Technology of Jammu, Chatha, Jammu-180009, J&K, India email:hafeezskuastj786@gmail.com __________________________________________________________________________

Spodoptera frugiperda is found widely throughout the warmer parts of the New World.

Damage results from leaf-eating and healthy plants usually recover quite quickly, but a large pest population can cause defoliation and resulting yield losses; the larvae then migrate to adjacent areas in true armyworm fashion. In the absence of natural biological control, fall armyworm can cause significant yield loss in maize and other crops.

There are many variables to consider in determining the potential yield loss due to fall armyworm infestation. In general, how the crop responds to fall armyworm infestation is highly dependent on the population level of the pest and the timing of infestation, natural enemies and pathogen levels that can help to naturally regulate the populations, and the health and vigour of the maize plant (nutritional and moisture status). Baudron et al.

(2019) have reported maize infestation of between 26.4 and 55.9% and impact on yield of 11.57%. Other authors have reported leaf, silk and tassel damage levels ranging between 25 and 50% and grain yield decrease of 58% (Chimweta et al., 2019). In Nicaragua, van Huis (1981) found a 33% increase in maize yield when plants were protected with insecticide.

Infestations during the mid- to late-whorl stage of maize development caused yield losses of 15-73% when 55-100% of the plants were infested with S. frugiperda (Hruska and Gould, 1997). Caterpillars of S. frugiperda appear to be much more damaging to maize in West and Central Africa than most other African Spodoptera species (IITA, 2016).

Monitoring of S. frugiperda Detection and Inspection Detection is facilitated by scouting fields for leaf feeding damage and by installing the pheromone traps for early detection, mass trapping and mating disruption mechanism.

25

Management strategies of Fall Armyworm (FAW), Spodoptera frugiperda on maize Monitoring: Installation of pheromone traps @5/acre in the current and potential area of spread in crop season and off-season.

Scouting: Start scouting as soon as maize seedlings emerge.

1.

At seedling to early whorl stage (3-4 weeks after emergence). Action can be taken if 5% plants are damaged.

2.

At Mid whorl to late whorl stage (5-7 weeks after emergence). Action can be taken if 10% whorls are freshly damaged in mid whorl stage and 20% whorl damage in late whorl stage.

3.

At tasseling and post tasseling (Silking stage).

Do not spray insecticides.

(No

insecticide application). But 10% ear damage needs action.

Cultural Measures: 1.

Deep ploughing is recommended before sowing.

This will expose FAW pupae to

predators.

2.

Timely sowing is advised. Avoid staggered sowings.

3.

Intercropping of maize with suitable pulse crops of particular region (e.g Maize/ pigeon pea/black gram/green gram).

4.

Erection of bird perches @ 10/acre during early stage of the crop (up to 30 days).

5.

Sowing of 3-4 rows of trap crops (e.g. Napier) around maize field and spray with 5% NSKE or azadirachtin 1500 ppm as soon as the trap crop shows symptom of FAW damage.

6.

Clean cultivation and balanced use of fertilizers.

7.

Cultivation of maize hybrids with tight husk cover will reduce ear damage by FAW.

8.

Application of Sand + lime in 9:1 ration in whorls in first thirty days of sowing.

Mechanical control: 1.

Hand picking and destruction of egg masses and neonate larvae in mass by crushing or immersing in kerosene water.

2.

Application of dry sand in to the whorl of affected maize plants soon after observation of FAW incidence in the field.

3.

Mass trapping of male moths using pheromone traps @ 15/acre.

Bio-Control:

26

1.

In situ protection of natural enemies by habitat management. Increase the plant diversity by intercropping with pulses and ornamental flowering plants which help in build-up of natural enemies.

2.

Augmentative release of Trichogramma pretiosum or Telenomus remus @ 50,000 per acre at weekly intervals or based on trap catch of 3 moths trap.

3.

Biopesticides: Suitable at 5% damage in seedling to early whorl stage and 10% ear damage with entomopathogenic fungi and bacteria.

a.

Entomopathogenic fungal formulations:

Application of Metarhizium anisopliae talc

formulation (1x108cfu/g) @ 5g/litre whorl application at 15-25 days after sowing.

Another 1-2 sprays may also be given at an interval of 10 days depending on pest damage or Metarhizium rileyi rice grain formulation (1x108cfu/g)@ 3g/litre whorl application at 15-25 days after sowing. Another 1-2 sprays may also be given at an interval of 10 days depending on pest damage. b.

Bacillus thuringiensis var. kurstaki formulations @ 2g/l (or) 400 g/acre.

Chemical Control: 1.

Seed treatment: Chemicals for seed treatment are under consideration of the Registration Committee and will be conveyed after approval of the Registration Committee.

2.

First Window (seedling to early whorl stage): To control FAW larvae at 5% damage to reduce hatchability of freshly laid eggs, spray 5% NSKE/Azadirachtin 1500 ppm @5m/l of water.

3.

Second window (mid whorl to late whorl stage): To manage 2nd and 3rd instars larvae at 10-20% damage spray Emamectin benzoate @ 0.4 g/l of water or Spinosad @ 0.3 ml/l of water or Thiamethoxam 12.6% + lambdacyhalothrin 9.5 %@ 0.5 ml/l of water or Chlorantraniliprole 18.5% SC @ 0.4 ml/l of water.

4.

Third window (8 weeks after emergence to tasseling and post tasseling): Insecticide management is not cost effective at this stage. Hand picking of the larvae is advisable.

All the sprays should be directed towards whorl and either in the early hours of the day or in the evening time.

Capacity building and mass awareness: 1.

Application and timely plant protection measures to avoid spread of the insect from the abandoned crop.

27

2.

Creation of awareness among important stake holders through trainings/group discussions.

3.

Community based and area-wide approach for implanting management strategies.

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Chapter-5

Feasibility of semiochemicals for the management of Fall army worm Dr. Devinder Sharma Assistant Professor Division of Entomology, Faculty of Agriculture, Sher-e-Kashmir University of Agricultural Sciences & Technology of Jammu, Chatha, Jammu-180009, J&K, India __________________________________________________________________________ Analyses of extracts of pheromone glands and of volatiles from calling female fall armyworm moths, Spodoptera frugiperda (J.E. Smith), revealed the presence of the following compounds: dodecan-1-ol acetate, (Z)-7-dodecen-1-ol acetate, 11-dodecen-1-ol acetate, (Z)9-tetradecenal, (Z)-9-tetradecen-1-ol acetate, (Z)-11-hexadecenal, and (Z)-11-hexadecen-1-ol acetate. The volatiles emitted by calling females differed from the gland extract in that the two aldehydes were absent. Field tests were conducted with sticky traps baited with rubber septa formulated to release blends with the same component ratios as those emitted by calling females. These tests demonstrated that both (Z)-7-dodecen-1-ol acetate and (Z)-9-tetradecen1-ol acetate are required for optimum activity and that this blend is a significantly better lure than either virgin females or 25 mg of (Z)-9-dodecen-1-ol acetate in a polyethylene vial, the previously used standard. Addition of the other three acetates found in the volatiles did not significantly increase the effectiveness of the two-component blend as a bait for Pherocon 1C or International Pheromones moth traps.

Introduction Chemical communication plays an important and essential role in the survival of insects, which enable them to appraise immediate environment through modification of their behavior. Semiochemicals are organic compounds used by insects to convey specific chemical messages that modify behavior or physiology [1]. The term semiochemical is derived from the Greek word “semeon� which means sign or signal. Insects use semiochemicals to locate mate, host, or food source, avoid competition, escape natural enemies, and overcome natural defense systems of their hosts. Semiochemicals have the advantage of being used to communicate message over relatively long distances compared with other insect means of communication such as touch. Semiochemicals have different

29

molecular weights depending on carbon chain. They are biologically active at very low concentration in the environment, thus their chemical characterization is complicated.

Fall armyworm (FAW), Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae), is native to tropical and subtropical regions of the Americas and is the key insect pest of maize in tropical regions. The genus Spodoptera includes several insect species that cause substantial damage to agricultural crops throughout the world. Three species, S. exigua (Hfibner), S. frugiperda (J.E. Smith), and S. eridania (Cramer), are serious pests of many crops in the United States. The fall armyworm (FAW), S. frugiperda, is an important pest of corn and other grass crops throughout the world, where it is known as the whorl- worm, and attacks a variety of crops (Andrews, 1980). FAW is a highly polyphagous insect pest that attacks more than 80 plant species, including maize, sorghum, millet, sugarcane, and vegetable crops [4]; nevertheless, maize is the main crop affected by FAW. According to a recent estimate, in the absence of control methods, FAW has the potential to cause losses of an estimated 8.3 to 20.6 m tons of maize per annum (valued at US$2481–6187 m) in 12 maize-producing countries in SSA, which accounts for approximately 20% of the total production in the region. FAW larvae cause damage to the plant by consuming foliage.

Young larvae mainly feed on epidermal leaf tissue and also make holes in leaves, which is the typical damage symptom of FAW. Feeding on young plants through the whorl causes deadheart. In older plants, the larger larvae in the whorls can feed on maize cob or kernels, reducing yield and quality. As is common with other major agricultural pests, the primary management strategy for FAW in the Americas is the use of synthetic insecticide sprays and genetically modiďŹ ed crops (Bt maize). Nevertheless, FAW has developed resistance to several synthetic insecticides for example, according to Abrahams et al., actioncategories1A (Carbamates) 1B (Organophosphates), and 3A (Pyrethroids-Pyrethrins). Furthermore, FAW resistance to Bt maize has been reported in different regions such as Puerto Rico, Brazil, Argentina, and the southeastern mainland USA. This suggests the need for an integrated management strategy for the sustainable control of this invasive pest.

Components of the FAW pheromone have been identified in previous investigations.

Sekul and Sparks (1967) used a laboratory bioassay in which a mating response was evoked in FAW males to monitor the isolation and identification of a sex pheromone, (Z)-9tetradecen-l-ol acetate (Z9-14: Ac), from FAW females. Subsequent tests showed this compound to be an ineffective lure for FAW males in the field (Mitchell and Doolittle, 1976; Sparks, 1980). However, this compound did reduce mating by FAWs when it was evaporated

30

into the atmosphere in disruption tests (Mitchell and McLaughlin, 1982). A second compound, (Z)-9-dodecen- 1-ol acetate (Z9-12 : Ac), was isolated and identified from FAW females (Sekul and Sparks, 1976), and this compound either alone or with small quantities of Z9-14:Ac added is a good practical lure for fall armyworm males when used in sticky traps (Mitchell, 1978; Jones and Sparks, 1979). However, fairly large quantities of Z9-12 :Ac are required for effectiveness (5-10 mg on a rubber septum), and the baits are effective in the field for only one to two weeks (Mitchell et al., 1983). Sparks (1980) reported that two additional compounds had been identified from washes of FAW female ovipositors, but he did not give their identity and he stated that they did not improve the effectiveness of Z912:Ac as a lure. Descoins and coworkers (personal communication) analyzed the FAW female-produced pheromone and found (Z)-ll-hexadecen-l-ol acetate (Zll- 16 : Ac), in addition to the two compounds already reported. However, in field tests conducted in Florida, we could not find a blend of these three compounds that was significantly better than Z9-12 : Ac alone in luring FAW males to sticky traps (Mitchell et al., 1983).

Potential use of semiochemicals in insect pest management Semiochemicals have been used for insect pest management more than 100 years ago.

Insect sex pheromones are the semiochemicals that are widely used for the management of insect pest particularly members of the order Lepidoptera. Aggregation pheromones from the order Coleoptera are also used for the management of agricultural insect pests of economic importance. Several serious agricultural pests including the carob moth Ectomyelois ceratoniae, the armyworm Spodoptera frugiperda, tomato leaf miner Tuta absoluta, fruit flies Bactrocera sp., mountain pine beetle (MPB) Dendroctonus ponderosae, Asian citrus psyllid Diaphorina citri, and the red palm weevil (RPW) Rhynchophorus ferrugineus, FAW (Fall army worm) have been successfully managed by using semiochemicals. Semiochemicals are considered safe and environmentally friendly molecules due to their natural origin, low persistency in the environment, and species specificity, which attribute much to their harmless effect on non-target organisms. However, there are some difficulties in the practical applications of semiochemicals in pest management, and due to these challenges Semiochemically-based pest methods are still at the beginning. Baker mentioned the reasons that promoted or hindered the adoption of pheromones in the management programs of insect species as follows: •

The biological differences in the mate-finding behavior of different species.

•

The chemistries of the pheromones used.

31

•

The successful engineering of the controlled-release dispenser and the use of proper trap design

•

The different political, economic, and use-pattern in different countries particularly the regulation of pheromones’ application.

32