Honey bee acetylcholinesterase inhibition: Insights into coumaphos tolerance

Conventionally phosphorothioates are activated to a more potent oxon metabolite with a greater affinity for acetylcholinesterase than the parent compound.  These 'activated' compounds normally exhibit greater toxicity to the organism.  Honey bees tolerate more coumaphos oxon than coumaphos.  The less toxic oxon metabolite is unusual and may be due to an insensitive acetylcholinesterase receptor.  In this study, we used Ellman's acetylcholinesterase inhibition assay to test whether worker and queen honey bee acetylcholinesterase receptors have a greater affinity for the parent compound or its metabolite.  We also compared the results to a suceptible house fly population.