Resistance Development in Spodoptera littoralis (Lepidoptera: Noctuidae) to Conventional and New Insecticides in Egypt

Background: Spodoptera littoralis Boisad. (Lepidoptera: Noctuidae) is a serious pest that harms crops all over the world. This pest is frequently treated with insecticides, but in many countries, its resistance impairs field control. The aim of the current study is to determine the resistance evolution to different insecticides in S. littoralis for the possibility of detecting susceptibility shifts that lead to poor control. Methods: Leaf-dip method was used to conduct the pesticides bioassay to determine the resistance stability to several conventional and new insecticides under laboratory settings in field population of S. littoralis. Results: Emamectin benzoate (2.00 ppm) was shown to be the most toxic compound based on LC50 values in the first generation, followed by spinosad (8.62 ppm), chlorantraniliprole (79.44 ppm), lambda-cyhalothrin (270.44 ppm), and profenofos (313.96 ppm). After twelve generations, the LC50 values for emamectin benzoate, spinosad, chlorantraniliprole, lambda-cyhalothrin, and profenofos decreased 4.88-, 9.91-, 9.42-, 16.52-, and 16.85- times, respectively, in field-collected of S. littoralis. The estimated drop in resistance was 17.08, 12.11, 11.96, 10.41, and 9.29 for emamectin benzoate, chlorantraniliprole, spinosad, profenofos, and lambda-cyhalothrin, respectively. Conclusion: According to the findings, insecticides with novel modes of action had higher reversal rates and less stable resistance to spinosad and chlorantraniliprole.