Population Dynamics of Aphid, Aphis gossypii Glover on Bt and non-Bt Cotton and Correlation with weather Parameters

Investigations on the population dynamics of aphid Aphis gossypii Glover on Bt (G.Cot.Hy.8 BG II) and non-Bt (G.Cot.Hy.8) were carried out at Main Cotton Research Station, Navsari Agricultural University, Surat, Gujarat during the Kharif, 2020-21. The incidence of aphids initiated in the first week of July (27th SW) in Bt cotton hybrid and in the second week of July (28th SW) in non-Bt cotton hybrid and continued till the crop harvest in the second week of January (2nd SW) in both the hybrids. The peak activity of aphids was recorded during the third week of December (51st SW) in Bt as well as non-Bt cotton hybrid. In both Bt and non-Bt cotton, the aphid population had a significant negative correlation with morning relative humidity. There was a highly significant negative correlation with minimum temperature, evening relative humidity, rainfall, rainy days, and a positive correlation with sunshine hours.