Comparison of Acute Toxicity of Different Groups of Pesticides to Honey Bee Workers (Apis Mellifera L.)

Abstract

Honey bees (Apis mellifera) forage in agricultural areas, and are exposed to diverse pesticide poisoning. Toxic effects on Apis mellifera of different groups of pesticides were tested in the laboratory; fungicide (Metconazole), herbicide (Glyphosate), acaricide (Amitraz), organophosphate insecticide (Fenitrothion) and neonicotinoid insecticides (Thiacloprid, Thiamethoxam, Imidacloprid, Acetamiprid, Dinotefuran and Clothianidin). Commercial formulations were serially diluted from the recommended concentration (RC) to 10<SUP>-6</SUP> times to carry out feeding and contact tests. Toxicity was transformed into lethal dose (LD<SUB>50</SUB>) and hazard question (HQ). The acute toxicity of pesticides showed similar patterns between feeding and contact tests. But feeding tests showed greater toxic to honey bee than contact test. The organophosphate and nitro-neonicotinoid insecticides were highly toxic with HQ values ranging greater than 1. However, cyano-neonicotinoids of Thiacloprid and Acetamiprid showed low toxicity. Even at the RC, 24 hr mortaliti es were 18 and 30%. The acaricide (Amitraz) showed intermediate level of toxicity at RC but negligible at the concentration lower than 10<SUP>-1</SUP> times. A fungicide (Metconazole) and herbicide (Glyphosate) showed minimal impacts. The results imply that the selective use of pesticides could help conservation of pollinators in agricultural production systems.