Pesticide degradation by gut microbes of the Colorado potato beetle
We explored the ability of the Colorado potato beetle's (CPB's) gut microbiota to detoxify pesticides. We screened 20 CPB gut bacterial isolates for the ability to degrade the pesticides malathion, fenitrothion and imidacloprid. We found three isolates that rapidly degrade malathion in vitro. Based on 16S amplicon sequencing of beetles from the same population (including the individuals from which the 20 focal isolates originated), we estimate that our focal isolates represent 60% of the CPB gut microbiota at the genus level. Within this 60%, we found that 11% of microbial sequences belong to genera with members that can mostly or completely degrade malathion, 26% belong to genera with members that can moderately or weakly degrade malathion, and 35% belong to genera with members that can weakly degrade fenitrothion. We did not detect any bacteria that degrade imidacloprid. While these are back-of-the-envelope estimates with many caveats, they suggest that this beetle population's gut bacteria have a high potential to degrade organophoshate insecticides.