Fourth International Bemisia Workshop International Whitefly Genomics Workshop
Influences of Bt Cotton on Population Dynamics of Bemisia tabaci
University of Florida, Gulf Coast Research and Education, Wimauma, Florida, USA. Correspondence: mannrs@ufl.edu
Bemisia tabaci (Gennadius) is a major sucking pest of cotton in India and other cotton growing areas of the world. The Indian government permitted commercial cultivation of genetically modified Bt (Bacillus thuringiensis) cotton in Northern India in early April 2005. One of the most prominent questions concerning Bt cotton is its effect on non-target organisms. The field experiments were conducted at Punjab Agricultural University, Ludhiana, to investigate the effects of Bt cotton on population dynamics of whitefly and predators in plots of Bt cotton and conventional cotton that received no insecticide applications and plots of conventional cotton in which insecticides were used regularly for control of bollworms. The results indicated that mean population densities of whitefly did not differ significantly in Bt cotton plots and conventional cotton plants. However, populations in Bt cotton plots showed fluctuations and reached peaks at different times than in conventional cotton. The population of predators (Chrysoperla, coccinelids, predatory bugs and spiders) was significantly lower in insecticide treated plots of conventional cotton than untreated plots of conventional and Bt cotton.