Monitoring the toxicity of cyantraniliprole to the field populations of Spodoptera litura (F.) feeding cole crops

Spodoptera litura, a significant insect pest of tropical agriculture, devastates more than 112 cultivated plants. It has become challenging to manage with insecticides alone as it develops resistance quickly. Cyantraniliprole, a newer insecticide under diamide, was introduced a decade ago and is widely used to manage several lepidopteran and hemipteran insects. This study was taken to look after the field efficiency of cyantraniliprole against S. litura and the possible mechanism of resistance development in cole crop regions of Tamil Nadu. The maximum LC₅₀ obtained was 0.20 mg/ I in Theni population and the least (0.11 mg/ I) in Dindigul, with no significant difference between the field populations. The resistance ratio observed in the field populations were between 1.89 - 1.09, indicating that the field populations were susceptible. Further, all three detoxifying enzymes, mixed function oxidase, glutathione S-transferase, and carboxylesterase, were found to differ irrespective of the time of insecticide exposure and the populations examined, indicating that they have no role against cyantraniliprole.