Effect of elevated CO2 and temperature on the life cycle of pink bollworm, Pectinophora gossypiella (Saunders) mediated by Bt cotton

Pink bollworm, Pectinophora gossypiella (Saunders) is the notorious pest and being a monophagy on cotton, the damage that it causes is alarming. Any changes in the nutritional quality of cotton will have direct influences on pink bollworm. In this regard, the host-mediated effect of eCO2 and temperature on the life cycle of pink bollworm, P. gossypiella on Bt cotton was studied in the open top chambers at the Center for Agro-climatic Studies, UAS, Raichur. The results revealed that variations in phyto-chemistry of Bt cotton particularly the cry toxin expression and nitrogen have reduced in elevated CO2 and temperature conditions which also reduced larval, pupal period, adult longevity, fecundity and incubation period. However, the total life span of pink bollworm did not show statistically significant differences among the climate change treatments. Similar results were noticed when pink bollworm was reared on Bt cotton collected from different open top chambers and reared separately in growth chambers and the same larvae were analyzed for their enzyme activity. A significant increase in the activity of midgut proteases (trypsin and chymotrypsin), carbohydrases (α-amylase) was noticed but lipase activity was reduced

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Not AvailableTo assess the impact of weather parameters on rice pests, a field experiment was conducted in rice ecosystem during 2013-2014 at Agricultural Research Station, Gangavathi, Koppal district of Karnataka. The rice insectpests infestation was monitored through light trap catches during 52 standard weeks of the study period and correlated with weather parameters. Results indicated high pest incidence during the months of October (Rabi, 2014). The favourable weather conditions for high incidence of rice leaf folder, leaf and plant hoppers were 38.80ºC mean temperature with a corresponding relative humidity that ranged between 85.30 to 92.80 per cent during the rabi season. The correlation studies made between BPH, WBPH and weather parameters revealed a positive relationship with morning relative humidity (r = 0.04 and r = 0.19) and evening relative humidity (r = 0.09 and r = 0.17), respectively. Whereas, high incidence of yellow stem borer (YSB) was observed in the second fortnight of April with a 37.43ºC and 52.71 per cent mean temperature and relative humidity, respectively. Maximum temperature had a positive effect on male (r= 0.31) and female (r= 0.24) moth of the yellow stem borer population.Not Availabl