Effects of the mycotoxins aflatoxin B1, deoxynivalenol and zearalenone on survival, biomass and toxin accumulation in Musca domestica larvae

Insects are receiving increasing attention as a possible ingredient for feed and/or food production. When used efficiently, insects can provide a sustainable and economically favourable contribution to global food security. Housefly larvae (HFL) can grow on a variety of organic side streams and upgrade them by partial conversion into high-quality protein. Organic side streams may be chemically contaminated by naturally occurring toxins, e.g. mycotoxins, therefore, effects on insect survival and biomass as well as other feed and/or food safety issues should be investigated. In this study, the HFL were exposed to a feed substrate spiked with aflatoxin B1 (AFB1), deoxynivalenol (DON) or zearalenone (ZEN) at concentrations of either 1 or 10 times the maximum levels or guidance values set for feed materials by the European Commission. Mortality and biomass of HFL were recorded over five days of exposure. LC-MS/MS analysis was used to determine the concentration of the mycotoxins in the substrate offered, the larvae and the residual feed material. A molar mass balance was calculated to estimate how much of the spiked mycotoxins (and several metabolites), was recovered in the larval body and the residual material. Exposure to either of the three mycotoxins did not affect larval mortality and biomass, and accumulation in the larval body did not take place. Metabolism does seem to occur for AFB1 and ZEN as the molar mass balance revealed an unrecovered fraction of ca. 40-50%. Little DON metabolism occurred as most of the initially present DON was found back unchanged. The results of this study support the potential for safe use of HFL as food- and/or feed when reared on mycotoxin contaminated side-streams, as accumulation of the tested mycotoxins did not take place in HFL. Further research is needed to identify the fate of the unrecovered fractions of AFB1 and ZEN.