Role of Detoxification Enzymes of Chlorantraniliprole Resistance in Field Strain of Cotton Leafworm, Spodoptera littoralis (Lepidoptera: Noctuidae)

Spodoptera littoralis (Lepidoptera: Noctuidae) is a major lepidopterous pest that damages many agricultural crops in Egypt and other countries. The intensive application of chemical insecticides to S. littoralis led to the development of resistance against several insecticides, including chlorantraniliprole. Although resistance to the novel anthranilic diamide chlorantraniliprole is less likely. To limit the spread of the resistant populations, chlorantraniliprole resistance was investigated in field population of S. littoralis with elucidation of the role of the metabolic enzymes. The field strain had a medium resistance ratio, RR = 34 to chlorantraniliprole compared with the susceptible strain, according to the results of bioassays using the leaf dip method. S. littoralis larvae of field strain treated with triphenyl phosphate (TPP), diethyl maleate (DEM), and piperonyl butoxide (PBO), showed synergistic ratios of 1.0-, 2.0- and 4.0-fold on chlorantraniliprole, respectively. Furthermore, results showed that the activities of monooxygenase (MO), glutathione S-transferase (GST), and carboxylesterase (CarE) increased significantly in the field strain compared to the susceptible strain. However, MO is most likely the main detoxifying enzyme in charge of chlorantraniliprole resistance. These results provide information about chlorantraniliprole resistance that can help in managing populations of cotton leafworm in fields.