Effects of Environmentally-Relevant Mixtures of 4 Common Organophosphorus Insecticides on Honey Bees

We assessed whether exposure to environmentally-relevant mixtures of four organophosphorus insecticides
(OPs) exerted adverse effects on honey bees. Adult and worker bees were orally exposed for five
days under laboratory conditions to mixtures of four insecticides, diazinon, malathion, profenofos and
chlorpyrifos at two concentrations. Concentration in the mixtures tested were equivalent to the median
and 95th centile concentrations of the OPs in honey, as reported in the literature. Effects on survival,
behavior, activity of acetylcholinesterase (AChE), and expression of genes important in detoxification
of xenobiotics and immune response were examined. Survival of worker bees was not affected by exposure
to median or 95th centile concentrations of the OPs. Activity of AChE was significantly greater in
worker bees exposed to the 95th centile concentration mixture of OPs compared to the median concentration
mixture. Expression of genes involved in detoxification of xenobiotics was not affected by treatment,
but the abundance of transcripts of the antimicrobial peptide hymenoptaecin was significantly
greater in worker honey bees exposed to the median concentration mixture. Results suggest that
short-term exposure to environmentally relevant concentrations of a mixture of OPs do not adversely
affect worker honey bees.

Al Naggar, Y., Wiseman, S., Jianxian, S., Cutler, G. C., Aboul-Soud, M., Naiem, E., … & Giesy, J. P. (2015). Effects of Environmentally-Relevant Mixtures of Four Common Organophosphorus Insecticides on the Honey Bee (Apis mellifera L.). Journal of Insect Physiology.82, 85–91