Neonicotinoid metabolism in honey bees

There have been reports of global decline in managed honey bees and wild bees around the world. The rapid dying of honey bee colonies was named “colony collapse disorder” (CCD) and has been linked to different factors. One of the factors are novel insecticides named neonicotinoids. The acute toxity and adverse effects on bees is not only limited to the parent compound, but their (intermediate) metabolites have been shown to be toxic as well. So far, partial metabolic pathways in honey bees were described for only three out of seven neonicotinoids in use. For the remaining four neonicotinoids the metabolism by honey bees is still unclear. The overall objective of this study is to elucidate the metabolism of orally administered neonicotinoids in honey bees. The specific objectives are to determine known and unknown neonicotinoid biotransformation products and their kinetics. The study will be divided into four phases. In phase I, neonicotinoids will be administered at two locations to groups of caged honey bees with a feeding solution containing a mixture of unlabeled and 13C-labeled neonicotinoids with doses up to LD50 and sampling at 8 time points. Next, the targeted compounds will be extracted with organic solvents. For untargeted analysis, an isotope assisted approach will be used with direct analysis of the extracts as to avoid loss of putative biotransformation products (Phase II). Data will be evaluated with the aid of comprehensive databases. Unknown neonicotinoid biotransformation products will be searched for by the “MetExtract II” software tool (phase III). Finally, in a field-experiment, real world honey bee samples will be collected and analyzed for the biotransformation products found in phase III. In our project, isotope-assisted methods will be used the first time to study how honey bees metabolize the seven commercially most frequently used neonicotinoids.