Population Density of Cotton Whitefly Bemisia tabaci and Mites Tetranychus urticae on Brinjal and Their Chemical Control

摘要

A study was conducted to evaluate seasonal abundance and efficacy of insecticides and miticides against brinjal pests i.e., cotton whitefly ( Bemisia tabaci ) and mites ( Tetranychus urticae ) at Agricultural Research Institute Tarnab Peshawar in June 2003. For density evaluation, plants were randomly selected for each pest. These plants were regularly monitored on weekly basis throughout the cropping season. During monitoring B. tabaci was first noticed in mid May and increased gradually up to the end of July with a peak (24.33/leaf), while decreased from first week of August until it vanished up to the end of September. Tetranychus urticae was first observed in late May and reached its peak (24.50/leaf) in early July and finally halted in the second week of September. Five insecticides and three acaricides were sprayed three times at 25 days interval against these pests. Efficacy of the insecticides/acaricides lasted for up to 15 days after spray. Confidor 20 SL was significantly better than the other insecticides against B. tabaci where the lowest population range, 1.18-3.03/leaf was recorded. Thiodan 35 EC provided next better protection against the pest. Pyrida 15 EC was the most effective miticide against Tetranychus urticae by lowering its population up to 1.12-2.65/leaf. Agrifol 20 EC and Ethion 46.6 EC gave next better control. While Ripcord 100 g L^-1 EC failed to show its effectiveness against Tetranychus urticae .