Potentials of animal, crop and agri-food wastes for the production of fly larvae

Fly larvae, in particular those of house fly (Musca domestica) and black soldier fly (Hermetia illucens), are increasingly considered for animal feed worldwide. A simple way to produce fly larvae is to expose suitable substrates to attract adult flies that will lay eggs in the substrates from where larvae will be subsequently extracted. This study aims to evaluate the potential of animal manures and agri-food wastes for maggot production and to identify the fly species developing in the substrates. Experiments were conducted in the Republic of Benin. Twenty-six substrates were left uncovered for 10 hours and maggots were harvested after four days. Fresh substrates were then added to residual substrates and left uncovered for another 10 hours for another production cycle. In total, three production cycles were monitored. In the first cycle, nearly 100% of the flies were house flies but black soldier flies appeared in the following cycles. The result showed that crop and agri-food substrates produced more larvae than manures. The highest yield at the first production cycle was obtained with the mixture of soybean bran and maize grain pericarp. Maize bran, pig manure and chicken manure also showed potential for maggot production. Other substrates such as cow and sheep/goat manure produced nearly no maggot when used alone but the amount of larvae substantially increased when attractants such as chicken offal were added, or when mixed with pig and chicken manure. Production decreased with the production cycles for the majority of substrates, except for mixtures based on spent grain and pineapple grain, which produced a large amount of larva at the second harvest. The activity of maggots led to temperature elevation and reduction of substrate biomass. This study showed that several substrates, in particular soybean bran, maize bran, pig manure and chicken manure show potential for maggot production.