resistance of egyptian field populations of spodoptera littoralis (lepidoptera: noctuidae) to emamectin benzoate and role of detoxification enzymes

Background: one of the most significant pests that harm numerous agricultural crops ‎is the cotton leafworm spodoptera littoralis (boisduval) and it has evolved resistance ‎to various insecticides across most chemical classes, including the novel insecticide ‎emamectin benzoate. ‎methods: the sensitivity of emamectin benzoate was evaluated in egyptian cotton ‎leafworm field populations. ‎results: according to bioassays performed using the leaf-dipping method, emamectin ‎benzoate sensitivity varied among 5 field populations, with lc50 values ranging from ‎‎2.78 to 6.86 ppm. two s. littoralis populations demonstrated the low levels of ‎resistance at resistance ratios (rr) between 17.9- and 22.3-fold and three populations ‎showed moderate resistance at 33.5 to 42.8-fold compared with a susceptible ‎population. the findings demonstrated that diethyl maleate (dem) and piperonyl ‎butoxide (pbo) have considerable synergistic effects on the toxicity of emamectin ‎benzoate. ‎conclusion: the results suggest that emamectin benzoate resistance in the s. littoralis ‎populations studied may be caused by the enzyme systems monooxygenase (mo) and ‎glutathione s-transferase (gst).‎highlights‎emamectin benzoate efficacy is decreasing in populations of spodoptera littoralis.‎‎emamectin benzoate resistance in littoralis field populations ranges from low to ‎moderate. ‎‎the field populations’ monooxygenase and glutathione s-transferase activity were ‎higher than those of the susceptible population‎.