The use of insecticides in agriculture can lead to residues being left behind in the product. The EU has set legal limits for this which are low enough to prevent humans and animals suffering any ill effects. However, new research by Wageningen University & Research has found that these low levels of insecticide can be harmful to an insect often used in animal feed and for human food products: the black soldier fly.
Black soldier fly
Larvae of the black soldier fly (Hermetia illucents) and other cultivated insect species are increasingly used as a food resource and can play an important role in improving the sustainability of the agricultural sector. The Wageningen study gave these insects feed treated with six different insecticides. The concentrations were equal to the legal limit for animal feed ingredients. Two of the insecticides (spinosad and cypermethrin) were clearly associated with reduced growth and survival of the larvae. This reduced survival was up to 72% with spinosad, and 22% for the combination of cypermethrin and piperonyl butoxide which is commonly used in practice. Following the experiment, the insects were checked for accumulations of the insecticides, as this would pose a risk to any humans or animals who go on to eat the insect. However, such accumulations were not found.
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Revising down permitted concentrations
Based on this study, the researchers recommend that policymakers revise down the permitted levels of residue concentrations in agricultural products destined to be used as insect feed.
Further research is also needed to test the large range of insecticides found in raw materials on the black soldier fly and other insect species cultivated for animal feed or for human consumption.
This research was published in the Open Access scientific journal PLOS ONE.
The study was carried out jointly between Wageningen Food Safety Research, the Wageningen University Entomology Laboratory, and the insect production company Bestico B.V. The study was partially funded by the Ministry of Agriculture, Nature, and Food Quality, as part of a public-private partnership (PPP) through the ‘Top Sectors’ policy.