Seasonal pattern of infestation by spotted bollworm,Earias insulana (Boisd.) and pink bollworm,Pectinophora gossypiella (Saund.) in field plots of Transgenic Bt and non-Bt cottons

A transgenic bt cotton line ir-fh-901 carrying cry1ac toxic gene from bacillus thuringiensis was evaluated for resistance against spotted bollworm earias insulana (boisd.) and pink bollworm pectinophora gossypiella (saund.) in punjab province,pakistan during 2007 and 2008. we found no significant differences in spotted bollworm egg density between bt and conventional cotton but larval density was significantly lower in unsprayed bt cotton than unsprayed non-bt cotton plots and insecticides were applied in sprayed non-bt plots to keep the pest population below the economic threshold level. the rosette flower density caused by pink bollworm infestation and number of pink bollworm larvae found in bolls of bt cotton were significantly lower than non-bt cotton plots. we conclude that transgenic bt cotton is more effective in season-long control of spotted and pink bollworm. copyright © 2015 zoological society of pakistan.