Agrochemical contaminants in six species of edible insects from Uganda and Kenya

Edible insects are currently promoted worldwide as an alternative animal protein source, but they are mostly still harvested from the wild where they are predisposed to contamination with agrochemicals. This study analysed six species of edible insects (Ruspolia differens, Rhynchophorus phoenicis, Schistocerca gregaria, Oryctes sp, Pachnoda ephippiata and Acanthoplus sp) collected from different habitats and/or reared in the laboratory in Kenya and Uganda for safety from agrochemical contaminants using liquid chromatography tandem mass spectrometry. The residue levels were statistically compared with the Codex Alimentarius Commission maximum residue limits (MRLs). Residues of only nine agrochemicals were detected in the insects out of 374 chemicals which were screened. The detected agrochemicals include two insecticides (aminocarb and pymetrozine), three herbicides (atraton, methabenzthiazuron and metazachlor) and four fungicides (carboxin, fenpropimorph, fludioxonil and metalaxyl). Ruspolia differens and adult Oryctes sp were free from detectable levels of any agrochemical. Whereas the pesticides residue levels in most insect samples were within maximum residue limits, some of them notably P. ephippiata from black soldier fly larval frass, R. phoenicis from oil palm and P. ephippiata from plant compost contained 2-, 8- and 49-fold higher levels of atraton, methabenzthiazuron and metazachlor, respectively, than MRLs. These findings demonstrate that edible insects may accumulate harmful residues of agrochemicals from the environment where they breed or forage, rendering them unsafe for human consumption or feeding animals. The mechanisms for possible bioaccumulation of these agrochemicals in the insects remains to be investigated. Development of methods for farming edible insects under regulated indoor conditions to ensure their safety as sources of food or feed is recommended.