ACUTE TOXICITY OF SOME BIOPESTICIDES AND THEIR EFFECT ON ACETYLCHOLINESTERASE OF HONEY BEE (Apis mellifera) WORKERS

Biopesticides are increasingly applied throughout Egypt. However, negative effects of these compounds on the honey bee (Apis mellifera L.), the most important pollinator for cultivated ecosystem, remained poorly investigated. The objective of our study was to evaluate the potential side effects of five biopesticides; bioarch (Bacillus megaterium), biofly (Beauveria bassiana), biozed (Trichoderma album), protikto BTK (Bacillus thuringiensis kurstaki), and spintor (spinosad) on mortality and acetylcholinesterase activity of honey bee workers. The mortality of treated workers was determined after 24 h of application, and the lethal concentrations that caused 50% mortalities (LC_50) were estimated. The impacts on acetylcholinesterase (AChE) activity were determined in vivo after 24 and 48 h in head, thorax and abdomen of surviving bees. Our results indicated that spinosad showed the most toxic action to adult honey bee workers with LC_50 of 11.60 mg L^-1 followed by biozed with LC_50 of 114.12 mg L^-1, and lower degrees of toxicity were obtained with protikto (LC_50 = 87,412 mg L^-1), biofly (LC_50 = 49,766 mg L^-1) and bioarch (LC_50 = 15,785 mg L^-1). In addition, all tested biopesticides caused various degrees of inhibition in AchE activity of adult honey bee workers (after 24 h of application) with the body region and with concentration. On the contrary, there were different degrees of activation in AChE of head, thorax and abdomen obtained after 48 h of application with tested biopesticides, except bioarch, biofly and protikto were inhibitions in AChE activities of the abdomen were obtained.