Side effects of imidacloprid, ethion, and hexaflumuron on adult and larvae of honey bee Apis mellifera (Hymenoptera, Apidae)

The honey bee is economically significant insect and plays an important role in the pollination of various plants. With regard to the widespread use of pesticides in agricultural lands, honey bees, as non-target and useful insect, inadvertently contact these chemicals. Thus, in order to evaluate the effects of some pesticides, the toxicity of three insecticides from different chemical classes including imidacloprid (0.16 mg a.i./l), ethion (79.47 mg a.i./l), and hexaflumuron (500 mg a.i./l) on detoxifying enzymes of worker honey bees and mortality of immature bees was investigated. These chemicals were selected because they are used globally and ingested by honey bees. The sub-lethal concentration of imidacloprid reduced the activity of the acetylcholinesterase (AChE) and glutathione S-transferase (GST). Exposure to the sub-lethal concentrations of the ethion reduced the esterase (EST) activities in treated honey bees. Exposure of honey bee larvae to imidacloprid (0.16 mg a.i./l), ethion (79.47 mg a.i./l), and hexaflumuron (500 mg a.i./l) increased the mortality of the treated group compared to untreated controls, but this difference was not statistically significant. Our results indicate that imidacloprid and ethion disrupt the physiology of honey bees, thereby reducing the efficiency of this beneficial pollinator. Also, it is important that additional studies be performed to investigate the sub-lethal effects of pesticides on larval development.