Population of whitefly, Bemisia tabaci (Gen) and its natural enemies in cotton field in Northwest India

The study was done to understand the seasonal occurrence of whitefly Bemisia tabaci (Gen) population and its predators and parasitoids in cotton crop in farmers’ fields in North West India. Roving field surveys were conducted in cotton growing districts of Punjab (Fazilka, Muktsar), Haryana (Sirsa) and Rajasthan (Sriganganagar and Hanumangarah) during June to October 2018. Whitefly population (adults/3 leaves) remained below ETL in June and crossed ETL at few locations during July-August and thereafter remained below ETL in all locations. Mean population (per three leaves) of whitefly was maximum in Fazilka (12.77) followed by Sirsa (6.79), Muktsar (3.86), Sriganganagar (3.03) and Hanumangarh (2.33). Among natural enemies predators Chrysopid and spiders were the dominant. Population of Coccinelid beetles was not found in most of the fields. Parasitization of whitefly nymphs by Encarsia spp. was maximum in July and August which coincided with the population of whitefly thereafter it declined due to spray of harmful insecticides. There were non-significant (P = >0.05) correlation between population of whiteflies and natural enemies.