Base-line susceptibility of Tribolium castaneum to various synthetic insecticides.

The red flour beetle, Tribolium castaneum (Herbst) is a cosmopolitan insect pest that causes severe loss in broad range of stored commodities worldwide. Chemical control has been considered as major preventive measure to manage this dangerous pest. Therefore, we have evaluated 22 different insecticides against T. castaneum collected from five districts of southern Punjab, Pakistan. Bioassays were performed to assess the LC50 values of considered insecticides. Our results showed that emamectin benzoate was the most toxic insecticide among all the insecticides. There was non-significant difference in toxicity of deltamethrin and triazophos to all tested populations based on overlapping 95% confidence interval of LC50. The spinosad was more toxic as compared with the spinetoram. In case of ketoenoles, spirotetramat was more toxic as compared with the spiromesifen. In case of acetamaprid and nitenpyram, there is non- significant difference in LC50 values of the all tested strains of T. castaneum based on overlapping 95%CI. We used four insect growth regulators (IGRS) including methoxyfenozide, pyriproxyfen, lufenuron and cyromazine as larvicides. The lufenuron was more toxic as compared with the pyriproxyfen, methoxyfenozide and cyromazine in most of the studied populations. Methoxyfenozide was moderately toxic. These results will provide help in establishing an effective management program for T. castaneum.