Pest s 13 00038

Journal of Pest Science Development of the Red Palm Weevil (Rhynchophorus ferrugineus; Curculionidae; Coleoptera) on Infested Coconut Palms: A New Invasive Coconut Pest in Malaysia --Manuscript Draft-Manuscript Number: Full Title:

Development of the Red Palm Weevil (Rhynchophorus ferrugineus; Curculionidae; Coleoptera) on Infested Coconut Palms: A New Invasive Coconut Pest in Malaysia

Article Type:

Original Paper

Keywords:

Rhynchophorus ferrugineus; Red Palm Weevil; coconut pest; invasive species; growth stages

Corresponding Author:

Wahizatul Afzan Azmi, Ph.D Universiti Malaysia Terengganu Kuala Terengganu, Terengganu MALAYSIA

Corresponding Author Secondary Information: Corresponding Author's Institution:

Universiti Malaysia Terengganu

Corresponding Author's Secondary Institution: First Author:

Wahizatul Afzan Azmi, Ph.D

First Author Secondary Information: Order of Authors:

Wahizatul Afzan Azmi, Ph.D Nurul 'Izzah Abdul Ghani, Bsc

Order of Authors Secondary Information: Abstract:

The development of different growth stages of the Red Palm Weevil (RPW), Rhynchophorus ferrugineus Olivier (Coleoptera: Curculionidae) were surveyed inside different parts (shoot, cabbage, petiole and trunk) of fifteen infested coconut palms, Cocos nucifera. A total number of 1,208 RPW which consists of 12 eggs (1.0%), 392 larvae (32.5%), 677 pupae (56.0%) and 127 adults (10.5%) were collected from this study. Higher numbers of RPW were found in petioles (770 individuals), followed by cabbages (194 individuals), trunks (142 individuals) and the least was shoots (102 individuals). Eggs of RPW were mostly found in cabbage part, whereas larvae were abundantly recorded inside cabbage (149 individuals) and petiole (161 individuals) of infested coconut palms. Significantly higher numbers of pupae (532 individuals) were found in petioles compared with other parts of coconut palms. This is due to the availability of fiber in petioles of coconut as fully developed larvae will compact most of the fiber to construct cocoon. Adults were mostly found in petiole (77 individuals) and trunk (30 individuals) of the infested coconut palms. The symptom and damage of each attacked part where different growth stages lived were also discussed in this paper.

This invasive weevil will be a threat to the coconut industry and, indeed, the survival of oil palm plantation. As this invasive weevil was relatively unknown, outcomes from this study will provide important information which is crucially for developing new control measures of this severe pest.

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COVER LETTER FOR SUBMISSION OF MANUSCRIPT Wahizatul Afzan Azmi Department of Biological Sciences Faculty of Science & Technology, Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu, Malaysia.

Subject: SUBMISSION OF A MANUSCRIPT FOR EVALUATION Dear Editor I am enclosing herewith a manuscript entitled “Development of the Red Palm Weevil (Rhynchophorus ferrugineus; Curculionidae; Coleoptera) on Infested Coconut Palms: A New Invasive Coconut Pest in Malaysia” for publication in the Journal of Pest Science for possible evaluation.

In general, this paper addresses the development of different growth stages of the Red Palm Weevil (RPW), Rhynchophorus ferrugineus – a new invasive pest of coconut palms in Malaysia on infested coconut palms. This is the first time that the RPW have been reported on coconut palms in Terengganu, Malaysia. It is hoped that this paper will provide information for the effective formulation to control this invasive coconut pest weevil, so that the necessary measures can be taken to prevent its further spread and to prevent significant economic yield losses.

With the submission of this manuscript I would like to undertake that the above mentioned manuscript has not been published elsewhere, accepted for publication elsewhere or under editorial review for publication elsewhere; and that my Institute’s (Universiti Malaysia Terengganu) representative is fully aware of this submission.

I am hoping that your Journal would consider the manuscript and thank you very much for your attention.

Yours sincerely, Wahizatul A. Azmi

*Manuscript with automatic line numbering Click here to download Manuscript with automatic line numbering: Manuscript_wahizatul.doc Click here to view linked References

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Development of the Red Palm Weevil (Rhynchophorus ferrugineus; Curculionidae; Coleoptera) on Infested Coconut Palms: A New Invasive Coconut Pest in Malaysia

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Wahizatul, Afzan Azmi* and Nurul ‘Izzah Abdul Ghani

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Department of Biological Sciences, Faculty of Science & Technology, Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu, Malaysia; Phone No.: +609-6683751 (office), +6013-9145457 (mobile), +609-6683326 (fax); Email: wahizatul@umt.edu.my

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Abstract

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The development of different growth stages of the Red Palm Weevil (RPW), Rhynchophorus ferrugineus Olivier (Coleoptera: Curculionidae) were surveyed inside different parts (shoot, cabbage, petiole and trunk) of fifteen infested coconut palms, Cocos nucifera. A total number of 1,208 RPW which consists of 12 eggs (1.0%), 392 larvae (32.5%), 677 pupae (56.0%) and 127 adults (10.5%) were collected from this study. Higher numbers of RPW were found in petioles (770 individuals), followed by cabbages (194 individuals), trunks (142 individuals) and the least was shoots (102 individuals). Eggs of RPW were mostly found in cabbage part, whereas larvae were abundantly recorded inside cabbage (149 individuals) and petiole (161 individuals) of infested coconut palms. Significantly higher numbers of pupae (532 individuals) were found in petioles compared with other parts of coconut palms. This is due to the availability of fiber in petioles of coconut as fully developed larvae will compact most of the fiber to construct cocoon. Adults were mostly found in petiole (77 individuals) and trunk (30 individuals) of the infested coconut palms. The symptom and damage of each attacked part where different growth stages lived were also discussed in this paper. This invasive weevil will be a threat to the coconut industry and, indeed, the survival of oil palm plantation. As this invasive weevil was relatively unknown, outcomes from this study will provide important information which is crucially for developing new control measures of this severe pest.

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Keywords: Rhynchophorus ferrugineus, Red Palm Weevil, coconut pest, invasive species, growth stages.

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Introduction

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The Red Palm Weevil (RPW), Rhynchophorus ferruginius Olivier (Coleoptera: Curculionidae) is one of the worst pests for cultivated palms (oil, date or coconut palms) in many parts of the world (Kaakeh et al., 2001; Faleiro, 2006). It is described as a pest of 26 palm species belonging to 16 different genera (EPPO, 2007). This invasive weevil is widely distributed, as it has spread from its native Southeast Asia, to Asia (including China and India), Northern Africa, the Middle East, Europe, Oceania (Australia, Papua New Guinea, etc.) and Caribbean (Aruba and Curacao) (EPPO, 2007).

In the Middle East, RPW is the most important pest of the date palm especially in Saudi Arabia, United Arab Emirates, Sultanate of Oman and Egypt (Bokhari & Abuzuhira, 1992). In India and Sri Lanka, it is considered as a serious pest of coconut palm (Nirula, 1956) and also oil palm (Misra, 1998) since it can completely destroy the plants. It has also been reported that RPW is a major pest of sago palm

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in Sarawak, besides R. vulneratus (Flach, 1983) and R. Schach (Bong et al., 2008). Due to that, RPW is listed on the A2 list of EPPO (European and Mediterranean Plant Protection Organization) as a significance serious pest (EPPO, 2007).

The state of Terengganu produced 11,220 metric tonnes of coconut on 2,440 hectares area, mainly along the 225 kilometers of BRIS, sandy soil coastal area (DOA, 2011). The devastating effect of the RPW was only realized when many dwarf variety coconut trees at the Department of Agriculture (DOA) Station at Rhu Tapai, Setiu was losing their leaf crown. A preliminary evaluation on the extent of damage based on visual symptom of suspected damage by RPW in 2007 by Plant Protection unit of the DOA, revealed that the damage had spread to 58 localities in all the seven districts of the state of Terengganu, stretching from Besut district in the north, bordering the state of Kelantan, to district of Kemaman in the south, bordering the state of Pahang. Apparently, the RPW damaged was confined to trees along the coastal areas. Its orgins are unknown but the theory surrounding its appearance is that the weevil could have been transported unwittingly in dates imported from the Middle East (Zazali C., personal comm.). Another speculation was that the weevil is believed to be introduced by date palm trees imported from Egypt a few years back for landscaping purposes without proper quarantine inspection (Zazali C., personal comm.). An intensive three month-survey in 2011 throughout Terengganu in over 800 ha of coconut plantations, villages, parks and in Federal Land Development (FELDA) plantations in all districts indicated that RPW caused the death of as many as 550,000 coconut trees, showing a drastic increase and rapid spread of RPW population (DOA, 2011). This invasive weevil has the potential to become one of the aggressive coconut pests which will threaten the coconut industry and indeed, the survival of oil palm plantations, the key economic growth driver of Malaysia.

The main aim of the present study was to determine the development of each growth stage (eggs, larvae, cocoon and adult) of R. ferrugineus (RPW) inside infected coconut palms and to investigate the symptom and damage of each attacked part (petiole, cabbage, trunk and shoot) of infected coconut palms where different growth stages lived. Findings obtained from this study is hoped will provide information on biological aspect of RPW in Malaysia, and therefore, an urgent action is needed to prevent significant economic yield losses before it is too late.

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Methods

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Survey on infested coconut palms and insect collection: Coconut palms in areas of higher infestation level of RPW recorded by the DOA since 2007 were inspected. The characteristic symptoms of RPW infestation on coconut palms were presence of tunnels on trunk and base of leaf petiole, oozing from the tree trunk, appearance of chewed up plant tissue with typical fermented odor and crown drying. A total of fifteen infested coconut palms that were seriously infested by RPW were cut down from June to October 2011 in selected coconut palm plantations in Terengganu. The locations were in Rantau Abang (4˚53’26.59’’N 103˚24’35.91’’E), Telaga Papan (4˚31’0’’N 103˚27’0’’E), Merang (5˚31’32.90’’N 102˚57’13.38’’E), Rhu Tapai (5˚30’49.88’’N 102˚58’36.34’’E), Marang (5˚12’08.89’’N 103˚12’01.21’’E) and Kuala Terengganu (5˚17’16.64’’N 103˚ 10’07.00’’E). Selected infected coconut palms were consist of four different varieties; such as MAWA with height 16-18 m (52-58 ft), at age 3648 years and diameter of 0.8-0.9 m (2-3 ft), Aromatic Dwarf or PANDAN with height 5-6 m (16-19 ft), at age 15-20 years and diameter of 0.6-0.7 m (1-2 ft), MATAG with height 4-5 m (13-16 ft), at age 15-20

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years and diameter of 0.6-0.7 m (1-2 ft) and Malayan Tall with height 20-22 m (65-72 ft), at age 35-40 years and diameter of 0.8-0.9 m (2-3 ft).

Occurrence and abundance of RPW stages in infested coconut palms: All the infested coconut palms were brought back to the laboratory of Department of Agriculture Terengganu (5˚16’51.12” N 103˚06’34.64”E) and were dissected and separated into different parts. Four different parts of coconut palms (shoot, cabbage, petiole and trunk) were observed in order to determine the occurrence and abundance of RPW stages (egg, larvae, pupae and adult). For observation on petiole part, each of the petiole was numbering according to the arrangement of the petioles. The lowest petiole was numbering as one. This was continued with the second and third lowest petiole and so on until all the petioles were marked with a number. All the petioles were removed and the total abundance of each RPW stage inside the petiole was recorded. After all the petioles were removed, the shoot was taken out. The occurrence and total abundance of each RPW stage inside the coconut’s shoot were recorded and calculated. Then, the coconut trees were cut into half. Similar procedure was done to determine the occurrence and total abundance of RPW stages inside the internal part (cabbage and inside the trunk). Alive samples of RPW were brought back to the laboratory in Universiti Malaysia Terengganu, placed under laboratory conditions at 26+0.20C; 75−80% of relative humidity (RH) and photoperiod of 12L:12D hr; and fed with coconut shoots.

Survey on symptom and damage of infested coconut palms: Symptom and damage were observed at different parts (petiole, shoot, trunk and cabbage) of infected coconut palms. Before the coconut palms were dissected, the entire symptoms that could be seen from outside the tree were recorded. When one by one petiole was removed out, the data on damages were recorded. Then the coconut tree was cut down into half. The damage inside the coconut tree (e.g. deep hollow or tunnel made by RPW inside the trunk and cabbage) were measured and recorded. Every part that has symptoms and damages made by RPW were photographed.

Data analysis: One-way ANOVA was used to evaluate the differences of the occurrence and total abundance of each RPW stage (egg, larvae, pupae and adult) on different parts of infected coconut palms (petiole, shoot, trunk and cabbage). Data were log(x+1) transformed to ensure normality in calculations of means and ANOVAs. Where there were significant differences, Bonferonni Post-hoc test was applied to determine which growth stages and different parts of infested coconut differed significantly from one another. All statistic analyses were conducted with SPSS 18.0 statistical software.

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Results

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 Occurrence and abundance of RPW stages in different parts of coconut palms A total number of 1,208 individuals which consists of 12 eggs (1.0%), 392 larvae (32.5%), 677 pupae (56.0%) and 127 adults (10.5%) were collected from this study. Figure 1 shows the pictures of RPW growth stages found on infected coconut palms. The occurrence and total abundance of RPW stages were different in every part of infested coconut palms (Figure 2). Significantly higher numbers of RPW were

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found in petioles (770 individuals), followed by cabbages (194 individuals), trunks (142 individuals) and the least was shoots (102 individuals) (F(3,56) = 21.446, p < 0.05).

In coconut shoots, 70 larvae (68.6%), 31 pupae (30.4%) and 1 adult (0.1%) of RPW were found, but no egg was recorded in the shoots. In cabbage part, more than half were larvae (76.8% = 149 individuals), followed by adults (9.8% = 19 individuals), pupae (8.2% = 16 individuals) and eggs (5.2% = 10 individuals). Larvae were the most abundant stage in cabbage of infected coconut palms compared with other stages (F(3,56) = 3.256, p < 0.05). In petioles, significantly greater numbers of pupae were found (69% = 532 individuals), followed by larvae (21% = 161 individuals) and adults (10% = 77 individuals) (F(3,56) = 20.557, p < 0.05). However, no egg was recorded in petiole part. In trunks, the highest number was the pupae (66.2% = 94 individuals), followed by adults (21.1% = 30 individuals), larvae (11.3% = 16 individuals), and only two eggs were found (14.1%). However, there was no significant difference of RPW stages in trunks of infected coconut palms (F(3,56) = 9.298, p > 0.05).

In shoot and cabbage of infested coconut palms, most of the instars occurred were in the early instars (1st to 4th instars). In contrast, larger larvae were mostly found in the petiole and trunk parts (5th to 8th instars). There was significant difference in total abundance of each larvae instar on different parts of infected coconut palms (F(7,365) = 103.55, p < 0.05). Post-hoc tests indicated that significantly higher number of 4th instar larvae was found in cabbage part compared with other coconut parts (F(7,365) = 3.508, p < 0.05), whereas larger number of 7th instar larvae was recorded in petioles of infested coconut palms (F(7,365) = 16.888, p < 0 .05).

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Based on our observation, RPW attacked the coconut palms in three ways. The first way was through shoot and straight to the cabbage of the coconut. The second way was through trunk, where adults of RPW made holes on the trunk or use the holes that already made by other insects. Usually the holes were made by Oryctes rhinoceros (Coconut rhinoceros beetle). The third way was through the root system, where adults of RPW dug the soil and got into the coconut palm root system.

When the coconut trees were infected, the shoots turned into brown in colour and became dry (Figure 3). Usually, the apical shoot were destroyed, broken and turned to umbrella-shaped or skirtingshaped, which indicated the critical stage of infestation (Figure 4). As such, the damage is devastating and cause the toppling of the crown and immediate death of the palm.

One of the symptoms that were frequently observed was the cracks (Figure 5a) and holes (Figure 5b) in petioles of infected coconut palms. There were two types of holes shapes, which were circle and oblong. Damaged petioles were dark in colour (Figure 5c), oozing out of thick brownish fluid from the tunnels, appearance of chewed up plant tissue and larvae were the major stage that caused damage in petioles (Figure 5d).

Similar shapes of holes on the trunks were also observed on the infected coconut palm which was suspected as co-attacked symptom made by O. rhinoceros (Figure 6). The soft tissues inside trunk were eaten by the larvae and turned to brownish and dark colour (Figure 7a). At the end stage of infestation, there was a deep hollow in the trunk and only hard tissues were left (Figure 7b). We observed many empty pupal cases (cocoons) attached in the inner side of the infected trunk (Figure 7c) with typical fermented odor.

Symptoms and damages of infested coconut palms

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In cabbage part, we observed that the soft tissue of the cabbage became dark in colour, sticky, full of RPW larvae and the presence of bore holes with chewed up fibres which gave out a very foul smell (Figure 8a). This usually happened to infected coconut palms that were in critical stage of infestation.

Figure 8b shows a hole in a cabbage that was made by RPW larvae which indicated as the initial attack of the cabbage.

The damages became worst due to increase in time of infection. In palms up to 5 years old, the larvae might be found in the crown and upper part of trunk at the soft tissues (Figure 9a). As palms advanced in age, the larvae were generally confined to the portions of the trunk closed to the growing point. In palms more than 15 years old, the larvae were generally found in the stem about 2-3 feet below the crown (Figure 9b), in the crown and bases of leaf petioles.

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Discussion

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ď&#x201A;ˇ Occurrence and abundance of RPW stages in different parts of coconut palms Results suggest that the occurrence and abundance of RPW at different developmental stages in infested trees were dependent on resource availability (white intact tissue) in shoot, cabbage, petiole and trunk.

Hunsberger et al. (2000) reported that the composition of larvae differed with resource availability in infested P. canariensis trees. In infested P. canariensis trees, there remained no white intact tissue at the peripheral part of the trunk and the base of petioles, and all or most of the larvae (more than 90%) were found mature.

To oviposit, females use the rostrum to bore into the softer portion tissue to form a hole in which to lay their eggs. On coconuts, oviposition occurs most frequently in crowns which have been damaged

by O. rhinoceros and that in young coconuts, oviposition takes place in wounds and at leaf scars. Eggs were laid in wounds along the trunk or in petioles, and also in wounds caused by the O. rhinoceros.

Usually, adult choose the soft tissue of the coconut palm to laying egg. Eggs laying position also depend on the type of attack. When the adult attacked coconut palms through trunk or root system, they laid the eggs in trunk or root part. The light-yellow eggs (approx. 2.5 mm long) are laid close to the surface of the incision or wound. Several are laid together but not in contact, and then the hole is cemented over to protect the eggs. This behaviour was possibly had effected the quantity of eggs that have been calculated.

Larvae were found in all parts of coconut palms, and significantly higher numbers of larvae were collected in cabbages and petioles of infected coconut palms. In early stages, larvae were mostly found within the heart (cabbage) of the coconut palms, in the soft tissues at the base of petioles or in the soft tissues of the palm trunk, where the larvae destroyed the vascular system. Larvae bore into the interior of the palms, feeding on the soft succulent tissues, discarding all fibrous material. Larvae have the ability to destroy vascular system of coconut trees because the mouthparts were well developed and strongly chitinized (Ajlan, 2000). They can also bore into the trunk of young palms and the decaying tissue of dying palms. The abundance of larvae was the highest in the cabbage because cabbage was the softer part in the coconut tree.

Larvae in the early instar (1st to 4th instars) were mostly found in cabbage, whereas the late instar th th (5 to 8 instars) were abundantly found in the petioles. The early instar larvae were serious feeders and they often penetrate and eat more soft tissues in cabbage. In contrast, the late instar larvae usually making a tunnel inside the petioles and feed on soft tissues of the petioles and usually prepared the fibres to built

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cocoon (Salama & Abdul-Razek, 2002). The early stage instar larvae were abundantly found in cabbage due to the large quantity of soft tissues than the other parts of coconut palms. As such, when the larvae grew bigger, the food source was reduced, and this forced the larvae to search for food to soft tissues at petioles part.

Greater numbers of pupae (inside the cocoons) were recorded in petioles compared with other parts, as the mature larvae need fibres to build a cocoon. Most of the fibres are found in the petioles part, thus it is suspected that the mature larvae will move to the petioles part when they are ready to become pupae. Mature larvae construct cocoon in the petioles pieces by chewed, left out fibres and then using the fibres to make a cocoon (Ajlan, 2000). The chewed behaviour will produce a tunnel and larvae usually make the cocoon inside the tunnel. Thus, most of the cocoons were found attached in the inner side of the tunnel at the petiole part.

Most of the RPW adults found in this study were the newly emerged adults from the cocoons collected in petioles or trunks of the infested coconut palms. When the adult emerge from the cocoons, they will disperse to other vulnerable coconut palms and cause fresh infestations especially in the nearby coconut palms. We found that when there were a lot of newly emerged adults in infested coconut palms, it indicated that the source of food (white intact tissue) in the tree was reduced or almost finished. Until the total destruction of the tree, the adults move to another host plant. Generally, the adult will only move to another palm tree when the one infested was completely destroyed and moves out in search of another host for food (Faleiro et al., 1999) RPW can have at least 3-4 generations inside infected coconut palms a year in southern Japan (Abe et al., 2009). In Egypt, El Ezaby (1997) reported that the weevil has three generations per year, the shortest generation (first) of 100.5 days and the longest (third) of 127.8 days. Several authors also reported that the weevil is able to complete several generations in a year, frequently, several generations can be passed in the same host tree before the tree collapses (Rajamanickam et al., 1995; Faghih, 1996).

Thus, it shows that possibly the RPW adults might mating and laid eggs in the same coconut tree if the resource of food still available.

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RPW attack coconut palms through shoot, trunk or root system. Adult usually used its rostrum to penetrate the part of coconut and go inside the coconut palms. RPW usually attacks transplanted or otherwise stressed palms but can attack healthy palms (Murphy & Briscoe, 1999). Adults are often attracted to stressed, damaged or dying palms (Wattanapongsiri, 1966) and rely on semiochemicals for aggregation (Giblin-Davis et al., 1996). On young, growing date palms, the weevils take shelter under the splitting bark and lay eggs within the newly emerging roots (Abraham et al., 1998).

Because the RPW is a concealed tissue borer, symptoms of attack at an early stage of infestation were difficult to detect although recent research has noted that it was possible to detect physiological changes in infested trees (Bokhari & Abuzuhairah, 1992). This raises the possibility that it may be feasible in the future to detect infestations before any symptoms are visible. Later in the infestation process the presence of larvae can be detected through the occurrence of hole on the trunk and at the bases of leaf petioles, and through the presence of frass and plant sap which oozes from these tunnels.

When a palm is severely infested, the stem or crown sometimes breaks off the tree (Abraham et al., 1998).

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Symptoms and damages of infested coconut palms

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The symptoms made by RPW also have been shown by other coconut pest, such as O. rhinoceros (Coconut rhinoceros beetle). Oryctes rhinoceros adult damage palms by boring into the center of the crown, where they injure the young, growing tissues and feed on the exuded sap. As they bore into the crown, the RPW will use the same hole or crack to deposit the eggs. Once the eggs hatch, the larvae will tunnelling and eat out galleries through the softest tissue, thereby doing a maximum amount of damage, since they destroy the heart of the palm cabbage.

Late instar larvae can kill palms by destroying the palm heart (cabbage) (Giblin-Davis & Howard, 1988). Palms are usually asymptomatic until the apical meristem has been damaged. Growing point of damage of palm trees located at the top of a trunk which is hard to detect until it had caused permanent damage. Damage to coconut palm was mainly caused by the larval stage feeding within the cabbage, petiole and trunk of palms. Usually, RPW infest palms below the age of 20 years, where the stem of the young palm is soft, juicy and easily penetrated (Hunsberger et al., 2000). This concealed feeding habit of larvae makes it more difficult to detect infestation at an early stage. Larvae and adults destroy the interior of the palm tree, often without the plant showing signs of deterioration unless damage is severe. Thus, visual examination allows detection of symptoms but cannot determine if there are larvae and adults present inside the coconut palms, making control efforts ineffective (Murphy & Briscoe, 1999).

It is hoped that the outcomes from this study will provide important information for the effective formulation to control this invasive coconut pest weevil, so that the necessary measure can be taken to prevent its further spread. An early action is needed to prevent further spread of the pest in other states of the region and to protect the coconut industry in Malaysia.

Acknowledgements We would like to thank to Zazali Chik and his supportive team from the Department of Agriculture of Terengganu State for the field work, Department of Biological Sciences, Universiti Malaysia Terengganu for the laboratory facilities and Ministry of Higher Education of Malaysia for providing Fundamental Research Grant Scheme (Vote No.: 59219).

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Figure Click here to download Figure: Figures.pdf

A)

B)

_______________ 2.6mm

C)

D)

Figure 1: RPW growth stages found on infested coconut palms, including of egg (A), larvae (B), pupae (inside the cocoons) (C) and adults (D).

A

B

C

D

Figure 2: Total abundance of R. ferrugineus (RPW) in different parts of infected coconut palms; shoot (A), cabbage (B), petiole (C) and trunk (D). Bars with the same letter are not significantly different, Bonferonni post-hoc test, p < 0.05.

Figure 3: Shoot of coconut palms that has been infected by RPW.

Figure 4: Drooping of dried leaves or umbrella-shaped of infected coconut palms.

B

A

C

D

Figure 5: Symptoms observed on the petioles of infested coconut palms; cracks (A) and holes (B). Damaged petioles were dark in colour (C) and appearance of chewed up plant tissue caused by the larvae (D).

Figure 6: Holes found on the trunks of infested coconut palms.

A

B

C

Figure 7: Deep hollow cavity of infested trunk (A), empty pupal cases (cocoons) attached in the inner side of infected trunk (B) and only hard tissues were left at the final stage of infestation (C).

A

B

Figure 8: The presence of bore holes with chewed up fibres (A) and a hole in a cabbage made by RPW larvae which indicated as the initial attack of the cabbage (B).

Figure 9: Damage found in the crown and upper part of coconut palms up to 5 years old (A) and damage occurred in the trunk 2-3 feet below the crown of coconut palms more than 15 years old (B)