Status of Insecticide Resistance in Spodoptera litura (Fab.) on Cotton in Guntur and Prakasam Districts of Andhra Pradesh
Experiments were conducted to assess the status of insecticide resistance in Spodopera litura (Fab.) on cotton in Guntur and Prakasam districts in Andhra Pradesh during 2003–2004. Guntur strain of S. litura showed 89.9, 49.6 and 31.3 folds at LD50 and 72.7, 39.8 and 31.8 folds resistance to chlorpyriphos at LD90 respectively at 24, 48 and 72 h after treatment. Correspondingly Prakasam strain of S. litura showed 97.2, 61.1 and 37.2 folds at LD50 and 94.0, 48.6 and 27.0 folds resistance at LD90 level to chlorpyriphos.