Impact of Elevated CO2 and Temperature on Growth and Development of Helicoverpa armigera Hubner
D. V. Sravan Kumar *
Department of Entomology, Agricultural College, Acharya N.G. Ranga Agricultural University, Bapatla-522101, Guntur, A. P., India.
P. V. Krishnayya
Department of Entomology, Agricultural College, Acharya N.G. Ranga Agricultural University, Bapatla-522101, Guntur, A. P., India.
M. Srinivasa Rao
Division of Crop Sciences, ICAR-Central Research Institute for Dryland Agriculture, Santoshnagar, Hyderabad - 500059,Telangana, India.
P. Anil Kumar
Department of Plant Pathology, Agricultural College, Acharya N. G. Ranga Agricultural University, Bapatla-522101, Guntur, A. P., India.
V. Srinivasa Rao
Department of Statistics and Computer Applications, Agricultural College, Acharya N. G. Ranga Agricultural University, Bapatla-522101, Guntur, A. P., India.
*Author to whom correspondence should be addressed.
Abstract
Climate change is an imminent and inevitable circumstance largely driven by increase in CO2 and temperature. CO2 directly affects plants through positive effects on net photosynthetic rate. Higher temperature during the crop growth phase can diminish the yield, with a longer growing season. In the present study, adverse climate conditions i.e. elevated CO2 (550 ppm) and elevated temperatures (29, 31, 33 and 35 ± 1 °C) were simulated in carbon dioxide and temperature gradient chambers (CTG). Growth and development of Helicoverpa armigera on non-Bt and Bt cotton leaves from those CTG chambers were recorded and correlated with foliar carbohydrates and proteins.It was found that protein content decreased by almost 42 % in non-Bt cotton and by 36 % in Bt cotton, while larval weight and duration decreased significantly with elevated conditions particularly in Bt cotton. Relative Growth Rate (RGR) increased with eCO2+ eTemp and is relatively less in non-Bt cotton compared to Bt cotton by 4-13 mg g-1 day-1. Lower protein content is positively correlated significantly to larval growth rate (r = 0.9**). Effects of climate change on crops and their pests have to be further quantified precisely to develop plausible stress mitigation strategies.
Keywords: Climate change, American bollworm, Bt cotton, carbohydrates, proteins, larval duration, RGR