Understanding Neonicotinoid Related Immunosuppression: A Potential for Beneficial Bacterial Intervention

The use of neonicotinoid pesticides has been implicated in the recent decrease of honey bee (Apis mellifera) populations. In this thesis, a Drosophila melanogaster model was used to characterize immune impairment associated with imidacloprid (neonicotinoid) exposure and test the ability of beneficial bacteria (lactobacilli) to alleviate these harmful effects. The experiments outlined in chapters 2 and 3 demonstrate that imidacloprid alters the gut microbiota by exploiting the cooperation between gut immune pathways. The pesticide reduces expression of Duox via dysregulation of the immune deficiency pathway resulting in decreased hydrogen peroxide production. This contributes to the microbiota changes but also depletes antimicrobial peptide expression through reduced nitric oxide signalling. By supplementing Drosophila with certain strains of lactobacilli, this immune impairment was mitigated. In summary, these studies show how a widely used pesticide contributes to honey bee losses by dysregulating their immune system; however, these effects can be countered by lactobacilli intervention