Selection and biochemical basis of chlorantraniliprole resistance in Helicoverpa armigera

Helicoverpa armigera Hübner (Noctuidae: Lepidoptera), is a pest of great agricultural importance because of its destructive and polyphagous nature. Synthetic insecticides are commonly used to manage H. armigera. Insecticide resistance development is a major challenge resulting into control failure. Detoxifying enzymes play a crucial role in insect adaptation or resistance to an insecticide through activation of metabolic mechanisms. We investigated the resistance potential of H. armigera against chlorantraniliprole through selection for twelve generations. The activity of glutathione-S-transferases (GST), esterases (EST) and Cytochrome P450 enzymes were also compared between chlorantraniliprole selected, unselected, and field populations. In our results, consecutive selection of H. armigera for twelve generations from G1 to G12 resulted in an increase in chlorantraniliprole resistance from 0.603-36.792 and 3.921-239.123 when compared with field population and lab population, respectively. Results further revealed enhanced GST (188.85 μmol min⁻¹ mg⁻¹ protein), EST (190.78 μmol min⁻¹ mg⁻¹ protein) and P450 activity (1.55 μmol min⁻¹ mg⁻¹ protein) in the midguts of 2^nd instar larvae of H. armigera after continuous exposure to chlorantraniliprole for 12^th generations. These results provide useful information for monitoring resistance in integrated pest management programs for H. armigera. Future investigations on downregulation strategies of detoxifying enzymes will improve pest management.