Influence of Bt cotton genotypes on natural enemies and its correlation to abiotic factors

Nineteen cotton genotypes comprising 17 Bt hybrids, one conventional hybrid and one variety were evaluated for population build up of natural enemies under unsprayed conditions at CCS Haryana Agricultural University, Hisar. The observations on natural enemies were recorded at weekly intervals. Mean population of spiders, predatory bugs (Geocoris spp.), green lace wing (Chrysoperla zastrowi sillemi) and coccinellids (Coccinella spp) ranged between 0.00–0.75/plant during 2008 and 0.06–0.68/plant during 2009. No adverse impact of Bt cotton was found on natural enemies population There was significantly negative correlation of population build up with temperature (r =-0.37) and rainfall (r =-0.15), while positive correlation with sunshine hours (r = 0.31) and relative humidity (r = 0.34).