SEASONAL DIVERSITY AND ABUNDANCE OF INSECT PESTS IN Bt AND NON-Bt COTTON FIELDS

The field study was conducted to investigate ‘Seasonal diversity and abundance of insect pests in Bt and non-Bt cotton fields at Palem village of Nalgonda district, Telangana state, India. Sample was done every month from July 2019 to January 2020 in the morning. Sweep net and hand-picking method was used for the collection of insect pests on Bt and non-Bt cotton plants. During 2019-2020 cotton seasons, a total of 5541 arthropod individuals in Bt cotton, 6822 arthropod individuals in non-Bt cotton fields were collected. More arthropod individuals were collected in non-Bt cotton than Bt cotton. During study period, a total 25 insect pests on Bt cotton and 38 insect pests on non-Bt cotton were recorded and which belonged to 20 different insect families and 3 different orders. We found 3- species of insect pests in July, 9 species in August, 12- species in September, 19-species in October, 19-species in November, 10-species in December and 7-species in January on Bt cotton and 4- species in July, 10 species in August, 12- species in September, 29-species in October, 28-species in November, 14-species in December and 9-species in January on non-Bt cotton fields during the study period. We found lower number of pests in Bt cotton in comparison to non-Bt cotton fields. Seasonal abundance was lower in both Bt and non-Bt crops in month of July-2019 gradually increased from July-2019 to November-2019, thereafter decreased from December-2019 to January-2020 on both Bt cotton and non-Bt cotton fields. We noticed that the low differences in abundance of insect pests between Bt and non-Bt cotton fields. Ecological indexes were calculated for analysis of community structure of insect pests.