STUDIES ON EFFECT OF Bt COTTON ON PREDOMINANT BIOAGENTS

A field experiment was conducted to study the effect of Bt cotton on predominant bioagents during kharif 2005 under unprotected condition at the experimental farm of Department of Genetics and Plant breeding, Marathwada Agricultural University, Parbhani .It has been found that reaction of Bt as well as Non-Bt to the population of lady bird beetle, grubs and adults varied from cultivar to cultivar. There is slight difference in population of F1 and F2 Bt cultivar whereas it varies significantly among Bt and Non Bt cotton cultivars. It has been found that population of predaceous spiders and syrphid maggots did not differ much among Bt and non Bt cotton cultivars. It was almost same in F1 and F2 cotton cultivars. This indicated that there was no difference with respect to predatory population which appeared more or less same in Bt and non Bt cotton cultivars. In case of parasitoid increase in population of was observed with an increase in population of bollworm. The population of predatory bugs in F1 was lower in Bt cotton cultivars as compared to non Bt cotton cultivars because of lower bollworm infestation.