Impact of Imunit® insecticide on survival and detoxification enzymes activity of adult worker honey bee (Apis mellifera L.)

Alpha-cypermethrin+Teflubenzuron (Imunit®) is an insecticide that is recommended by Iran Plant Protection Organization (IPPO) for the control of the cotton bollworm (Helicoverpa armigera Hübner) in tomato fields. In this research, the effect of Imunit® was assessed on survival rate of adult worker honey bees (Apis mellifera L.) in laboratory conditions. Newly emerged (≤24-h old) and forager (>21-day old) bees were treated with the field recommended dose of this insecticide via three types of exposure (residual contact, oral, or spray). In addition, the sublethal effects of Imunit® on the specific activity of some detoxifying enzymes including α-esterase, β-esterase, and Glutathione S-transferase (GST) was studied. The toxicological tests illustrated that the toxicity of Imunit® varies with age of the bee and the type of exposure. Except for the spray method, forager bees were more susceptible than newly emerged ones to this insecticide. Imunit® was significantly more toxic to newly emerged bees when applied as residual contact and spray than orally, whereas foragers showed more sensitivity after contact exposure to the residues of this insecticide. Activity of the detoxifying enzymes also changed regarding the bees' age and the means of exposure to Imunit®. In general, our findings demonstrate the high potential of Imunit® in the intoxication of honey bees.