Effects of veterinary drugs on rearing and safety of black soldier fly (Hermetia illucens) larvae

Insect proteins are expected to be increasingly used for food and feed. Black soldier fly larvae (BSF, Hermetia illucens) can convert low quality organic substrates, such as manure, into protein-rich ingredients for food and feed. However, pig and chicken manure can contain residues from antibiotics and anti-parasitic drugs, resulting from treatments of the animals for diseases. This study aimed to evaluate the possible effects of veterinary drugs on black soldier fly larvae rearing, including growth and survival, as well as on the presence of residues in the larvae. The study focused on regularly found veterinary drugs in manure. Five-days old larvae were exposed to either 0.05 and 0.5 mg/kg flubendazole (FLUB), 0.05 and 0.5 mg/kg ivermectin (IVM), 0.5 and 5 mg/kg doxycycline (DOX), 0.5 and 5 mg/kg flumequine (FLUM) or 0.5 and 5 mg/kg sulfadiazine (SULF) for one week. The growth of larvae reared on substrate with IVM (0.5 mg/kg) was significantly lower than the control, while the survival of the larvae was not affected. The growth and survival of the larvae was not affected by the other treatments. Chemical analyses showed that concentrations of the veterinary drugs in the larvae, after exposure, were generally low. Only DOX concentrations in the larvae were high; these levels would exceed the European Commission maximum limit for DOX in meat products. Mass-balance calculations showed possible degradation or metabolism of veterinary drugs by the larvae, except for SULF. In conclusion, when using manure as substrate for BSF rearing, the possible presence of veterinary drugs in manure should be carefully controlled to ensure optimal insect growth and safety of the insect products.