In the past all species of edible insects were harvested in the wild. But nowadays farming techniques have been developed for some species. House crickets (Acheta do mesticus), palm weevils (Rhynchophorus f errugineus) and mealworms (Tenebrion m olitor) are successfully farmed in Thailand. House crickets and palm weevils are used mainly for human consumption, while mealworms are commonly used as pet foods (for fish, birds and geckoes or lizards).
Cricket farming
At the start of technology development for cricket farming in the northeast in 1996, two common cricket species Gryllus bimaculatus De Geer and Teleogryllus testaceus Walker, both native to the region, were introduced to farmers. However, a few years later, the house cricket (Acheta domesticus), commonly called sading, was brought in to replace the native crickets and now is commonly farmed in the northeast and other parts of Thailand (Figure 2). The farmers prefer to breed house crickets rather than native cricket species even though the period of development from egg to adult of the two cricket species is similar (45 to 60 days). The main reason for this preference is that house crickets have a better taste, particularly the females because of the many eggs inside their abdomens; the eggs are delightfully crunchy.
Cricket-breeding techniques have not changed since they were first introduced. House crickets are bred in various containers such as concrete tanks or concrete block pens covered with a mosquito or nylon net to keep crickets in and predators out. Bedding is often made from a layer of rice husks but some breeders do not use any material.
Cardboard egg cartons are often used to provide crickets with a place to hide. The most commonly used food for crickets is commercial chicken feed with 14 to 21 percent protein content, and a few days before harvest, pumpkins or vegetables. As soon as the male crickets stridulate, bowls containing a mixture of husk and sand are placed in the breeding enclosure for crickets to lay eggs in. After a few days, the bowls are moved to another breeding tank for incubation and hatching at a stable temperature. This reproduction cycle can be repeated one to three times for each generation. It takes 40 to 45 days from the egg stage until harvesting of the adults.
Three kinds of products (mature crickets, cricket eggs and fertilizer from waste produced from the cricket farms) can be sold. However, the main product is the adult crickets.
Cricket breeders usually sell their crickets through wholesale buyers who supply market vendors or restaurants, and sometimes directly to local consumers or to gecko or fish breeders for feed.
In order to promoting public awareness of cricket farming, including cricket consumption and stimulating the market demand for crickets, many related activities have been undertaken. One, beginning in 1996, was the introduction of small-scale cricket farms for students at primary schools. This activity not only provided education by integrating the cricket-farming activities with school extra-curricular subjects, but also produced additional protein for the student school lunch programme. These integrated cricket-breeding lessons at the school level were quite successful and the students enjoyed having cricket farms at their school. Moreover, cricket cooking fairs and competitions were also occasionally organized for public awareness purposes.
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Figure 2. Cricket farm in Khon Kaen Province. C (a) House cricket (Acheta domesticus); (b) common cricket (Gryllus bimaculatus); (c) breeding containers. Courtesy Y.
Hanboonsong)
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Palm weevil farming
The palm weevil (Rhynchophorus f errugineus Oliver) is found mainly in the southeast region of Thailand. Local people have been breeding palm weevil on lan p hru trees (cabbage palm, Corypha utan Lam.) and sago palm (Metroxylon sagu Rolth.) since 1996 for home consumption (Figure 3). Palm weevil larvae became a popular food for people in the southern region and other areas around 2005. Because of this increase in demand, palm weevil breeding has expanded into commercial-scale farming in many provinces in the south of Thailand.
Palm weevil breeding still depends on natural plant food so up till now palm weevil farming cannot be expanded into other regions where lan phru trees and sago palm are not found.
Two breeding methods are used for palm weevil farming. The traditional method is breeding directly in palm trunks or stems. Cabbage palm or sago palm trunks or stems are cut into 50-centimetre lengths and adult males and females are released on top. After 40 to 45 days palm weevil larvae can be harvested. The second method is a modification of the traditional technique. Breeding takes place in a plastic container. Instead of using an actual palm tree, a round plastic container filled with ground palm stalk and mixed with pig feed is used.
Feed formula for each insect species farmed
Approximately half of the production cost of insect farming is in the feed which is commercially produced for the chicken industry. Therefore cricket farming is vulnerable to price increases in that sector. This potential risk could undermine profitability for cricket farming. Research is needed to find low-cost or free protein sources to develop into a special feed formula for crickets. Palm weevil depends on natural food sources like sago palm trees. Accordingly there is the risk that palm trees will be threatened by overharvesting and pressure from ecological organizations may create a negative image and limit consumer acceptance, especially if the consumer base is to expand to Europe and the United States.
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Figure 3. Palm weevil farming in southern Thailand. (a) Adults and larvae;
(b) sago palm tree; ( c) plastic container filled with ground palm stalks and mixed with pig feed; (d) breeding colonies; (e) sago worm dish.
Courtesy Y. Hanboonsong