Edible Insect Production Systems

include premium priced products, such as insects reared on substrates from certified organic crops or other high-value inputs. Eventually, commercial producers in Africa will need to comply with the same regulatory standards as those in the EU and US markets. For example, all edible insect substrates must be preconsumer, meaning no postconsumer waste can be included in the substrate. These quality standards will result in a steady rise in the unit cost of commercial production, possibly to the point at which commercial producer product prices equal rural producer prices.

Market segmentation may eventually affect insect prices and production schemes in rural areas. Africa’s poor transportation infrastructure to rural communities will limit commercial producers’ ability to reach rural consumers. In response, commercial producers are likely to acquire or partner with successful small-scale, rural producers and introduce capital, information, and technology to rural producers. This would bring down the unit cost of insects and insect products in rural markets. Since rural consumers are typically poorer and, therefore, price sensitive, a slight reduction in insect prices would likely displace some small-scale community insect production systems. In this scenario, an out-grower scheme may develop whereby the small-scale farmer subcontracts displaced rural farmers to rear insects (figure 4.7). The displacement of small-scale producers would not necessarily end household insect production, which is used primarily for home-based insect consumption and not for selling.

EDIBLE INSECT PRODUCTION SYSTEMS

This section describes the production systems for houseflies, crickets, mealworms, silkworm chrysalids, palm weevil larvae, and BSF.

Houseflies

Houseflies have a short and simple production cycle. The housefly (Musca domestica, L. (Diptera: Muscidae)) is found everywhere in the world that humans settle (van Huis et al. 2020). Adult females lay their eggs in moist, nutrient-rich environments—such as food waste and manure—and can lay up to 500 eggs in their lifetime. One must only leave substrates open and wild houseflies will naturally lay their eggs there. The 3- to 9-millimeter larvae (maggots) hatch within 8 to 20 hours and feed immediately on the substrate on which the eggs were laid. Larvae go through three instar stages over three to five days and then pupate. After two to six days, pupae develop and emerge as adults. The housefly’s adult life stage lasts up to 25 days. The housefly has a short larval growth phase and a long adult phase during which it actively feeds. This contrasts with the BSF, which has a short adult phase during which it does not feed and consumes only small amounts of water. Houseflies are disease vectors, so housefly mass rearing structures must follow correct procedures to ensure that the flies are well-contained.

Housefly larvae that are reared on waste substrates show potential as an efficient animal feed source in Africa (Kenis et al. 2018; Koné et al. 2017; Sanou et al. 2018; Pomalégni et al. 2017). In Benin, a survey shows that 41 of 714 poultry farmers used housefly larvae to feed their poultry. Most of the farmers using housefly larvae were in southern Benin and, on average, were better educated than other farmers. These farmers also tended to raise larger chicken flocks in a confined system, in contrast to open scavenging systems, and also had higher poultry-related incomes than poultry farmers who did not use housefly larvae. The farmers who used housefly larvae also tended to use other innovative insect feeds for their poultry, including termites (Pomalégni et al. 2017). Houseflies’ larvae can biodegrade manure, fish offal, slaughter blood, cereal or legume waste, and other low-quality organic matter streams. These streams are then rapidly assimilated into the insect’s biomass. One kilogram of dry organic waste can be turned into 150 to 200 grams of fresh housefly larvae. Moreover, the larvae’s short life cycle limits the amount of substrate it can consume; therefore, the same substrate may be used for larvae production for two cycles (Ganda et al. 2019).

Crickets

Crickets have become a popular insect to farm because they have a good flavor and can be domesticated. Wild crickets are consumed in many traditional diets in Asia and Africa because they are tasty and easy to prepare. People consume full-sized adult crickets, which resemble small shrimp in size and appearance, unlike other edible insect species, which people consume as larva. The cricket species that are most ideal for farming are known as colonial crickets because they live in large groups, or colonies, and can be kept in high densities. Other wild cricket species have solitary behavior and are not suitable for domestication. Crickets belong to the Orthoptera insect order. As such, crickets hatch from eggs and develop from a nymph stage to a mature adult stage when, stepwise, they molt their chitin exoskeleton (instars). The cricket production cycle has three stages: (1) hatching eggs, (2) growing hatched nymphs to maturity for harvest, and (3) mating and egg laying for the next cycle.

Cricket farming has several key characteristics. Cricket farming structures comprise a series of containers in which batches of crickets are produced to maturity. Different types of cricket farms are shown in photo 4.1. In simple systems, cricket eggs are hatched and nymphs grow to adults in the same container. In more advanced systems, the egg hatching and first instar stages of nymphs are kept in different containers to adjust the temperature and humidity to create an ideal environment for each stage. The productivity of the cricket farming system is determined by three factors: the egg hatching rate, the nymphs’ survival rate, and the growth rate of nymphs to mature adults for

PHOTO 4.1 Examples of Cricket Farms

a. Good agricultural Practices–certified Acheta domesticus cricket farm in Thailand b. Gryllus bimaculatus cricket farm in northeast Thailand

c. InsectiPro’s cricket farming system in Kenya

Photographs (panels a and b) © Nanna Roos / University of Copenhagen. Used with the permission of Nanna Roos. Further permission required for reuse. (panel c) © Dave de Wit / InsectiPro. Used with the permission of Dave de Wit. Further permission required for reuse.

harvest. The cricket’s substrate and environmental conditions, primarily temperature and humidity, are also key factors. According to studies from Kenya (Orinda et al. 2017; Kinyuru and Kipkoech 2018) and Cambodia (Miech et al. 2016), and studies carried out under laboratory conditions (Morales-Ramos, Rojas, and Dossey 2018), the optimal temperature for hatching and growing crickets ranges between 25°C and 30°C.

Feeding crickets requires meeting the cricket’s nutritional requirements from available substrates. In Thailand, cricket feed has a similar nutritional composition to common chicken feeds (Halloran 2017; Halloran et al. 2017). However, since this feed is suited for chickens, it is not fully optimized for the specific nutritional needs of crickets. Crickets can also consume fruits, vegetables, and even weeds. Public and private sector feeding experiments are identifying the nutritionally optimal feed sources for crickets (Magara et al. 2019; Dobermann, Michaelson, and Field 2019; Neville and Luckey 1962; Veenenbos and Oonincx 2017).

Cricket value chains are complex and varied. The general value chain for farming crickets is illustrated in figure 4.8. Farmers sell adult crickets for direct human consumption or further processing and can sell cricket eggs and nymphs to other farmers to start new colonies or add to existing colonies to prevent inbreeding. Farmers can also sell cricket frass, a production byproduct that can be turned into a biofertilizer, to other farmers to fertilize crops or vegetable gardens. These value chains vary by country. In Uganda, farmers sell their fresh crickets, both Acheta domesticus and Gryllus bimaculatus, to a research project for a fixed price. In Madagascar, farmers dry and pulverize the crickets before selling the powder to a nongovernmental organization, which uses it to increase the protein and nutrient content in foods for undernourished children. In all the surveyed cricket farming countries, farmers sell cricket eggs to other current or potential insect farmers. In the Democratic Republic of Congo and in Kenya, farmers sell crickets to wholesalers, who in turn sell them to vendors. The vendors can then sell the insects fresh or cooked. In Kenya, farmers sell crickets to fish breeders and chicken farmers.

Different cricket management and processing practices create products of various uses and properties. In Thailand, it is a standard practice to feed pumpkin to crickets during the last days before harvest to improve their taste and golden color from the pumpkin beta-carotene. Thai cricket farmers also manage their colonies to have more females than males, which increases the market value because females carry eggs inside, making them tastier. Crickets are often dried and pulverized into flours of different properties. For example, the Gryllus species’ flour is darker than the house cricket’s flour. The most common cricket flour is processed as whole flour, for which the entire cricket is ground up. Cricket flour can be defatted, separating the protein from the fat, to improve the flour’s quality for certain applications