Technical basis for the small-scale production of Black Soldier Fly meal as fish feed in Benin

Producing fish of good quality and at a lower cost is the major objective of fish farmers. In Benin, the feeding of farmed fish is a major predicament. The food composition suffers from the lack of a reliable sources of protein. Hermetia illucens (Diptera: Stratiomyidae) larvae could offer a real solution as they have already been used in several countries in animal production. However, the species is little known in Benin and breeding techniques are ignored by producers. The present study aims at establishing a technical reference for the breeding of this fly in Benin. A larvarium (42 cm x 29 cm x 25 cm) equipped with an automated prepupa harvesting system was manufactured for the rearing of the larvae. A total of 36,000 larvae were used in the trials. Three densities (1 larva/g, 2 larvae/g, 3 larvae/g) have been tested in triplicate in 2kg of chicken feed in order to determine the optimal load density. The experiment lasted 12 days during which growth tests (e.g. weight measures) were conducted. The quantities of fly meal produced from each treatment were evaluated as the total cost of production. Results show that the larvarium designed is suitable for H. illucens larval rearing and that the automatic prepupa harvesting system is efficient. The load density determined as ideal for good larval growth is 2 larvae per gram of chicken feed. With 40 g of 1-week-old larvae, it is possible to produce about 500g of insect meal. The overall production cost came to roughly $ 265, which makes it quite affordable. The proposed rearing system is a high-yield one and is within the reach of any fish farmer or farmer in general. Other types of substrates such as restaurant waste, manure or agricultural co-products could be explored in order to replace the chicken feed.