Bioefficacy evaluation of imidacloprid 17.8% SL and thiamethoxam against whitefly on tomato and their effect on natural enemies

The study was conducted at the Regional Research Station, Bidhan Chandra Krishi Viswavidyalaya, Jhargram, Paschim Medinipur, West Bengal (India) during tomato growing season of 2014 and 2015 to evaluate the effectiveness of imidacloprid and thiamethoxam as foliar application against the whitefly (Bemisia tabaci). The experimental result revealed that imidacloprid @ 175 ml/ha was the most effective treatment with 100% control of pest population at 5 days after spray and also with minimum population at 10 and 15 days after spray. This was followed by the treatment imidacloprid @ 150 ml/ha and thiamethoxam @ 200 g/ha. Imidacloprid @ 175 ml/ha and 150 ml/ha had a better efficiency against whitefly than thiamethoxam. These two insecticides did not affect spider population but the coccinellid population was reduced with increase of doses of imidacloprid. Imidacloprid @ 175 and 150 ml/ha were found more toxic than thiamethoxam @ 200 g/ha and imidacloprid @ 125 ml/ha. This result revealed that imidacloprid had more adverse effect on coccinellids than thiamethoxam