Coumaphos metabolism in honey bee, Apis mellifera, queens and workers

Coumaphos toxicity bioassays on honey bee (Apis mellifera) workers and queens indicated both castes tolerate much more oxon metabolite than the original phosphorothioate compound, with queens tolerating approximately 3 times more coumaphos and 10 times more oxon than workers.  As the honey bee target site is not insensitive, with honey bee acetylcholinesterase readily inhibited by coumaphos oxon, honey bee metabolism of coumaphos appears to be exceptional.   Metabolism of coumaphos by workers and queens was examined using HPLC and GCMS.  Specifically, the metabolite of coumphos oxon, was quantified after treatment of coumphos in honey bee queens and workers.  Bees were treated with known doses of coumaphos, washed in acetone to remove any remaining unpenetrated residues, and frozen at 5 known timepoints.  Coumaphos and coumaphos oxon was then quantified in both acetone wash and individual honey bees.  It is possible coumaphos is detoxified, rather than activated, by p450s to coumaphos oxon which is then hydrolyzed and removed from the honey bee.  In this case, differences between workers and queens may be explained by detoxicative capacity.