Impact of Chlorantraniliprole Exposure on Nutritional and Physiological Responses of Lab-Selected Susceptible and Resistant Populations of Spodoptera litura (Fabricius)

Spodoptera litura (Fabricius) (Lepidoptera, Noctuidae), known for its ravenous feeding habits, is a polyphagous pest with a high reproductive rate, often developing resistance to most of the conventional insecticides, posing a substantial pest management challenge. Chlorantraniliprole (CTPR) is an anthranilic diamide insecticide, which is widely used against lepidopteran pests, including S. litura. Understanding the physiological and biochemical alterations associated with CTPR resistance is crucial for effective resistance management. Our research aimed to investigate the overall impact of CTPR on nutritional parameters, and biochemical and immunological responses in laboratory-selected susceptible (Unsel-Lab) and resistant (CTPR-Sel) S. litura populations. Results showed a reduction in nutritional parameters and digestive enzyme activity, with a more pronounced decline in the CTPR-Sel population. In contrast, detoxification enzyme activities (MFO, GST, EST, ACP and AKP), along with AChE, were significantly elevated, suggesting an adaptive response to CTPR exposure, with the CTPR-Sel population exhibiting a stronger detoxification capacity. Antioxidant enzyme assay indicated increased SOD activity but decreased CAT activity in both populations, reflecting oxidative stress. Immune response markers, including total haemocyte count, lysozyme and phenoloxidase activity, showed significant variations between the two populations, suggesting differential immune-physiological adaptations. These findings highlight the physiological trade-offs associated with CTPR resistance in S. litura and emphasise the necessity of integrated pest management strategies to mitigate resistance development.