Impact of Environmental Resistance Factors on Abundance of Spotted Bollworm, Earias vittella Fabricius and Helicoverpa armigera Hubner on Bt and Non-Bt Cotton in Odisha

The field study aimed to assess impact of environmental resistance factors on population dynamics of Earias vittella Fabricius and Helicoverpa armigera Hubner on Bt and non-Bt cotton was conducted at the Regional Research and Technology Transfer Station, Bhawanipatna, Kalahandi. The results revealed that the transgenic Bunny Bt cotton incorporated with Cry 1Ac and Cry 2Ab remained absolutely free from bollworms infestation throughout the crop season in 2013 and 2014. However, in non-Bt of same Bunny hybrid, the peak incidence of E. vittella with damage of terminal shoots (5.96%), squares (12.97%) and bolls (9.55%) were noticed at 35th, 45th and 38th SMW. Similarly, the peak occurrence of H. armigera damage to squares (6.07 %) and bolls (11.08 %) was recorded at 41st and 40th SMW in both the years. Maximum larval population E. vittella and H. armigera were noticed during 38th to 41st SMW in both the years. The correlation coefficient of larval population of both the bollworms and oviposition by H. armigera with the weather parameters remained non-significant.