Edible insects - a culinary curiosity?
Edible insects may not be considered a delicacy in the West but for many cultures, they are an important source of protein. They can be consumed in their larval stage (e.g. grubs and caterpillars, including silkworms) or in their adult form (e.g. grasshoppers and ants). In Thailand, over 50 species of insects may be consumed throughout the year, and in Ecuador 83 different species have been recorded as an important complement to other sources of animal protein. In parts of Asia, the sago grub (Rhynchophorus ferrungineus) is considered an important food and in the western lowlands of Irian Jaya, the grub has become part of a complex cultural system. The adult beetle only oviposits on damaged or felled sago palm so villagers manage the sago palms in order to increase the number of eggs laid and to provide a consistent amount of larvae that can be collected six weeks later. In Japan, insects are sold as canned foods and in China, many insects are consumed for medicinal purposes. Overall, around 2000 edible insect species have been recorded around the world.
Insects are efficient recyclers of organic matter and they can provide a reliable and sustainable source of food for humans and/or animals, provided appropriate breeding methods are developed. Raising insects is relatively easy: they require minimal space and have a better conversion (feed to meat) ratio than any other meat. Most species are also lower in fat and higher in protein (7-21 grams of protein per 100 grams of edible insect) than larger livestock meat (beef, pork and chicken). They are also an important source of vitamins (in particular, riboflavin and thiamine) and minerals (mostly zinc, copper and iron). Traditional consumption involves eating the insects raw, boiled or roasted. However, for those not used to adding insects to their daily menu, they can be powdered and used as flour.
Mealworms (Tenebrio molitor) are well suited to 'insect farming'. These beetles are small, reproduce quickly and are resistant to disease and parasites. In addition, they are simple to handle and require little space (small plastic containers) and maintenance. The mealworms can be fed on oats or other types of grain and moisture is provided by pieces of vegetable or fruit. There are four stages to the life cycle (egg, larva, pupa and adult) which takes about one year to complete. Larvae can be harvested from the first generation and used as required because insects, like meat, deteriorate quickly. They can be killed by freezing or boiling. Crickets are also quite easy to raise and prepare but they require a large well-sealed container, as these insects are liable to escape. Like mealworms, they can be fed on grain and vegetable scraps and can be harvested within a few months.
Insect larvae can also be raised to feed to animals. Termite larvae are traditionally harvested from existing termatariums and fed to poultry as a protein supplement. However, experiments in Togo and Burkina Faso to provide a source of food (straw/leaves) for termites and site (cattle dung/soil) for a new colony have proved successful. In addition, maggots from Musca domestica and Sarcophaga sp. flies raised on animal droppings in West Africa have been fed to chickens. Chironomid larvae are also raised on chicken manure, harvested, cleaned and sold as feed to fish culture farms in Hong Kong. However, although these larvae can provide a valuable and cheap protein feed for fish and poultry, these insects can be a significant source of micro-organisms and the risks of disease transmission to domestic animals and humans should be considered.