EFFICIENCY OF SOME CHEMICAL INSECTICIDES IN CONTROLLING MUSTARD APHID AND THEIR IMPACT ON PREDATORY LADY BIRD BEETLE

Abstract

The study was conducted in the experimental field of Sher-e-Bangla Agricultural University, Dhaka during the Rabi season 2014-2015 to evaluate the effectiveness of some promising insecticides on aphid population abundance as well as their impacts on the incidence of predatory lady bird beetle in field and laboratory condition. The treatments composed of five chemical insecticides viz., foliar spray of Morter 48 EC (chlorpyrifos) @ 1 ml/L of water, Imitaf 20 SL (imidacloprid) @ 1 ml/L of water, Marshal 20 EC (carbosulfan) @ 1 ml/L of water, Ripcord 10 EC (cypermethrin) @ 1 ml/L of water, Diaraz 60 EC (diazinon) @ 1 ml/L of water and an untreated control. Among five insecticides, Imitaf 20 SL performed as the most effective insecticide in reducing the highest percent of aphid population on leaves (60.00%) whereas Ripcord 10 EC showed the least performance (39.54%). In inflorescence, Morter 48 EC performed as the most effective insecticide in reducing the highest percent of aphid population (68.06%) whereas Imitaf 20 SL showed the least performance (53.57%). In stem, Ripcord 10 EC performed as the most effective insecticide in reducing the highest percent of aphid population (62.69%) whereas Diaraz 60 EC showed the least performance (57.73%). In pod, Imitaf 20 SL performed as the most effective insecticide in reducing the highest percent of aphid population (61.11%) whereas Ripcord 10 EC showed the least performance (58. 22%). Under field condition Ripcord 10 EC reduced the highest number of lady bird beetle population, the percent reduction was (63.74%) and the least reduction was performed by Imitaf 20 SL (55.56%). In laboratory condition the highest percent of aphid reduction performed by Imitaf 20 SL (90.00%) and the least performance was Diaraz 60 EC (66.67%) as it was the highest percent of lady bird beetle reduction performed by Imitaf 20 SL (44.00%) and the least performance by Ripcord 10 EC was (28.67%). The maximum yield obtained from treatment Imitaf 20 SL (812 kg/ha) due to lower aphid abundance. On the other hand, low yield performance obtained from the T6 treatment due to an untreated control (310.2 kg/ha).