STUDY ON THE BIOLOGY OF MEALYBUG INFESTING BRINJAL AND ITS CHEMICAL CONTROL

Abstract

The experiment was conducted at the farm of Sher-e-Bangla Agricultural University, Shere- Bangla Nagar, Dhaka to evaluate the biology of mealybug and effect of some chemical insecticides on mealybug attacking brinjal in the field during the period from June, 2014 to October, 2014. Mean developmental periods of 1 st , 2 nd , 3 rd , instar nymphs and adults were 5.6, 8.4, 9.8 and 12 days respectively. Six insecticides were applied in replicated brinjal field. The treatments were T1: T-mectin 1.8 EC (Abamectin) @ 2.0 ml/L of water at 7 days interval; T2: Fighter 2.5 EC (Lambda cyhalothrin @ 1.0 ml/L of water at 7 days interval); T3: Voliam flexi (Thiamethoxam + Chlorantraniliprole @ 1.0 ml/L of water at 7 days interval); T4: Sevin 85 WP (Carbaryl @ 2.0 g/L of water at 7 days interval); T5: Dursban 20 EC (Chlorpyriphos @ 2.5 ml/L of water at 7 days interval); T6 : Admire 200SL (Imidachloprid @ 1.0 ml/L of water at 7 days interval); and T7 (untreated control). The result revealed that treatment T5 (Dursban @ 2.5ml/L of water) treatment was the most effective for reducing mealybug 90.22, 67.37, 64.22 and 83.84 respectively from leaf, twig, flower and fruits. The treatment T3 showed 77.17, 56.84, 45.87 and 56.57 respectively for reduction of these insect pests from those plant parts and T6 had the least performance over control. Dursban was also most effective insecticide for increasing fruit number and weight per fruit 205.83 and 41.23% respectively and in T6 it was 50 and 11.57% respectively. In terms of yield Dursban treatment was most effective increasing yield (130.23%) followed by T3(100.2%) and T1 (63.66%) treated plot. The application of Dursban at 7 days intervals was the best effective treatment for the control of mealybug pests in the brinjal field.