LETHAL TOXICITY OF NEONICOTINOID INSECTICIDES TO INDIAN HONEYBEE, APIS CERANA INDICA F.

Study assessed neonicotinoid toxicity to bees through oral, indirect contact, and topical application bioassays.All neonicotinoids demonstrated significant toxicity with LC50 values for imidacloprid, thiamethoxam, acetamiprid, dinotefuron, and clothianidin, respectively at 0.38, 1.11, 1.29, 0.26, 1.18 ppm (oral); 0.54, 1.33, 1.89, 1.22, 1.24 ppm (indirect contact); and 0.33, 0.40, 0.64, 0.47, 1.07 ppm (topical).Imidacloprid was found to be highly toxic with toxicities 3.39, 3.50, and 3.24 times higher and safety indices of 0.76, 1.08, and 0.66 for oral, indirect contact, and topical methods, respectively.Dinotefuron followed, with oral and indirect contact toxicities 4.96 and 1.54 times higher than that of imidacloprid and safety indices of 1.04 and 4.88, respectively.Thiamethoxam showed 2.67 times higher toxicity than that of dinotefuron with a safety index of 1.60 through topical application.Acetamiprid was the least toxic with safety indices of 6.45 and 9.45 for oral and indirect contact assays, while clothianidin had a safety index of 4.28 through topical application.These findings indicate that dinotefuron is the most toxic to bees in oral tests, while imidacloprid is highly toxic in both indirect contact and topical applications.Acetamiprid was found to be safer for bees in oral and indirect contact assays and clothianidin was safer in topical applications.The study reveals significant neonicotinoid toxicity to Indian bees with imidacloprid being particularly detrimental, emphasizing the need for mitigation strategies in Indian agriculture to protect bee populations.