Grant: Discovery Grants Program - Individual

Having shown in our current NSERC Discovery Grant that lactobacilli can perform detoxification of heavy metals, aflatoxins and pesticides, we now wish to identify the mechanisms involved in mitigating the pesticide effects. This is important to counter colony collapse disorder in honey bees. Nothing endangers the global food supply more than the loss of these pollinators. Our preliminary findings suggest that commonly used pesticides impair insect immunity making them more susceptible to a variety of pathogens. Hypothesis We hypothesize that members of the genus Lactobacillus harbor the ability to detoxify pesticides that endanger honey bees and other life forms. Long term goals The long-term goal of this research program is to advance our knowledge of an important bacterial genus with a long history of safe use in foods and supplements, and to exploit attributes that counter environmental chemicals and improve the survival of pollinators. Research objectives 1.1.Characterize how lactobacilli mitigates the immunosuppressive effects of pesticides and susceptibility to pathogens 2.Determine the functional capacity of lactobacilli to detoxify agriculturally-relevant xenobiotics. Methodological approach We will use Drosophila melanogaster as a well-established and strongly predictive model of the honey bee to determine how lactobacilli affect the co-modulatory response of innate immunity (highly conserved across broad taxonomic range) towards pesticides and/or pathogens as they apply primarily to honeybees, but also other hosts. We will utilize our stocks of RNAi-mediated knockdown and overexpression mutants of the DUOX and Imd pathways, and couple these knockouts with qPCR-based measurement of Imd and DUOX pathway-related gene expression and immunofluorescent stain relevant immune proteins. We will expose flies to different classes of pesticides: neonicotinoids, organophosphates, carbamates, Roundup (glyphosate), acephate, ?-cyhalothrin, oxamyl, tetraconazole administered at different concentrations. Lactobacillus rhamnosus GR-1, L. plantarum Lp39, L. kunkeei BR1, L. reuteri RC-14, L. rhamnosus GG and strains from African bees will be used to counter the pesticides and determine if they can actually degrade the chemicals. We will compare the microbiota in bees from healthy hives to that of hives infected with P. larvae, Melissococcus plutonius, N. apis, N. ceranae, Ascosphaera apis, Crithidia bombi or Varroa destructor, pathogens that will be examined in vitro for the ability of the lactobacilli to inhibit them. The Drosophila model will also be used to test various lactobacilli for their ability to modulate detoxification pathways. Significance The net result will be to develop an understanding of how lactobacilli strains can counter the most widely used pesticides through their degradation, and by modulation of insect immune responses, microbiota resilience, and countering key honey bee pathogens.