Conventional to Bt Cotton Vis-à-Vis Bollworms to Whitefly: Cotton Cultivation Again Under Threat in Northern India

The Bt-cotton since its introduction in 2005 in North India has witnessed upsurge in sucking insect-pests every season. This may be attributed to decrease in insecticidal sprays in post-Bt era, susceptibility of the germplasm being introduced as cotton hybrids and the failure of existing spray technology to reach throughout the bushy cotton hybrids. The Bt-cotton received the first blow only two years after the introduction in the form of the outbreak of mealy bug in 2007. In 2010, there was heavy incidence of whitefly along with cotton leaf curl disease across Punjab. The big blow to cotton production has been reported in 2015 resulting in loss of nearly 50-60 % cotton across state. There has been a complete failure of the insecticides to manage the pest and 40-50 percent of the area under cotton was ploughed in the middle of the cotton season. The whitefly population remained far above ETL from July to September. The situation at the farmers’ field was worse; the average population at 20 and 15 locations surveyed in July and August was 188.8 and 185.5 whiteflies per leaf, respectively. The population came down drastically down i.e.42.6 whiteflies per leaf in the end of September, however it maintained its ETL status during this period. Whitefly populations are largely regulated by the climatic factors such as temperature, rainfall and humidity. High temperature with high humidity has a positive correlation with the population build-up of this pest. The situation in 2015 was the most favourable for whitefly in terms of the high humidity which remained above 80 % from July till September. The paper discusses the current status of whitefly as pest of cotton and key factors for its outbreak in the state in context to pre and post Bt-cotton era.