Impact of Selected Insecticides on Apis mellifera L. (Hymenoptera: Apidae) under Controlled Conditions.

The present study was conducted in conjunction with the efforts to study the contact toxicity of some insecticides i.e. acephate, lambda-cyhalothrin, diafenthiuron, profenofos and spirotetramat against adult workers of Apis mellifera L. These insecticides were frequently being used to control different insect pests of major crops in Punjab-Pakistan. The experimentation was performed under laboratory conditions (28±2°C and 65±5% R.H). Four different concentrations (i.e. 50 ppm, 100, 200 and 400 ppm) of each insecticide were evaluated against A. mellifera as derived from their recommended field doses. Mortality of A. mellifera was recorded at 0.5, 3, 6 and 24 hours after exposure to insecticides. To evaluate the toxic impact, median lethal concentration (LC₅₀) of each tested insecticide was determined. The results obtained, revealed that all insecticides were highly toxic after 24 hours of exposure at maximum concentration. Acephate and lymda-cyhalothrin showed the maximum toxicity with their LC₅₀ of 83.96 and 139.07 ppm, respectively while diafenthiuron and profenofos were moderate in toxicity with LC₅₀ values of 150.53 and 169.42 ppm, respectively. Spirotetramat was the least toxic in this experiment with a LC₅₀ of 181.51 ppm after 24 hours of exposure to tested bees at maximum concentration of 400 ppm. After adjusting these results of tested insecticides to their commercial formulated field dose applications, they were causing a potential threat to A. mellifera at their maximum recommended dose except spirotetramat. [ABSTRACT FROM AUTHOR]