Evaluation of Oviposition Preference for Different Host Crops by Cotton boll worm, Helicoverpa armigera (Hubner) in Bt Cotton Dominated Patch

The effect of crop patch size on oviposition preference of H. armigera was studied under control condition. The results showed that there was significant difference in egg density among the treatments. The highest egg density was recorded in patch having 25% of Bt cotton (9.56%) followed by 50% of Bt cotton (8.94%) and 70% Bt cotton (5.48%) treatment. The reduction in egg density was recorded with increasing Bt cotton patch size. The results showed that there were significant differences in egg density (%) on other tested crops. The pigeon pea had the highest density (71.27%) followed by tomato (12.73%) and cotton (9.56%) whereas maize (6.42%) had lowest egg density. This indicates that pigeon pea was most preferred crop for oviposition in Bt cotton ecosystem. The domination of Bt cotton in ecosystem was found affecting on the oviposition behavior of H. armigera, it avoid oviposition on Bt cotton with increasing patch size. It is advised to use pigeon pea as refuge crop for resistance management in Bt cotton ecosystem.