Assessing the influence of alternating temperature on growth and development of Pectinophora gossypiella (Saunders) in Bt cotton

Pectinophora gossypiella one of the most destructive pests of Bt cotton. P. gossypiella gradually became a serious threat after gaining resistance to Bt toxin after 2 decade owing to which resulted in huge economic losses to the cotton growers. Present investigation was carried in order to study the most favourable temperature of P. gossypiella for its growth and development under various altering temperature regimes (20:30°C, 24:30°C,28:30°C, 20:35°C, 24:35°C, 28:35°C, 20:40°C, 24:40°C and 28:40°C) of Integrated Pest Management Laboratory, Department of Entomology, PAU, Ludhiana during cotton crop season 2022-23. Three models (linear and nonlinear) were used to estimate the relation between temperature and development rate of different instars and stages of P. gossypiella . The results revealed that duration of all larval instars and total larval duration were significantly short at an alternating temperature of 28:40°C. The pupal duration, adult longevity and total developmental period of male and female were recorded significantly low at the alternate temperature of 28:40°C. The fecundity and survivability (egg, larval and pupal)was significantly highest at 28:30°C, whereas the larval and pupal weights were significantly highest at an alternate temperature of 28:35°C. The correlation between developmental parameters and fecundity showed significant negative correlation. The survival of egg, larva and pupa showed non-significant negative correlation, whereas the larval and pupal weights show non-significant positive correlation with alternate temperatures. Stinner nonlinear and Inverse second order polynomial model provided more suitable temperature conditions for the development of P. gossypiella .