Effects of Environmentally-Relevant Mixtures of Four Common Organophosphorus Insecticides on the Honey Bee (Apis mellifera L.)
1 Department of Zoology, Faculty of Science, Tanta University 31527, Tanta, Egypt.
2 Toxicology Centre, University of Saskatchewan, 44 Campus Drive, Saskatoon, SK, Canada.
3 Department of Environmental Sciences, Agricultural Campus, Dalhousie University, Truro, NS, Canada.
4 Biochemistry Department, Faculty of Agriculture, Cairo University, Giza 12316, Egypt.
5 Department of veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, Saskatchewan
6 Department of Zoology, and Center for Integrative Toxicology, Michigan State University, East Lansing, MI, USA
7 Department of Biology & Chemistry and State Key Laboratory in Marine Pollution, City University of Hong Kong, Kowloon, Hong Kong Special Administrative Region, Peoples Republic of China
8 School of Biological Sciences, University of Hong Kong, Hong Kong Special Administrative Region, Peoples Republic of China
9 State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Peoples Republic of China.
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 diazinon, malathion, profenofos and chlorpyrifos. 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.