Effects of insecticidal treatment on the Yield and Control of major Insect Pests of Soybean (Glycine max (L.) Merrill) in South-eastern Nigeria

Abstract

Field experiments were conducted in 1995 and 1996 at Umudike southeastern Nigeria to compare the effectiveness of lindane, cypermethrin, deltamethrin and dimethoate in the control of the major insect pests and yield of soybean. The major insect pests found infesting soybean at 26 to 56 days after planting (DAP) in all the insecticidal treatments were the defoliators, Monolepta duplicata Sahl and Ootheca mutabilis Sahl while the stink bugs, Nezara viridula Linnaeus and Aspavia armigera Fabricius attacked soybean from 56DAP to 86DAP, respectively. During both years, it was found that the insecticides significantly (P<0.05) reduced the insect populations when compared with the control; with cypermethrin being the most effective. However, lindane was found to have more adverse effect on the predator, Mantis religiosa L. (Mantidae). It was also found that the insecticides significantly (P<0.05) increased the yield of the crop when compared with the control. Seed yield reductions of 48.4% and 46.7% were recorded in the control when compared with cypermethrin treated plots in 1995 and 1996, respectively. This suggests that cypermethrin could be used for effective control of the defoliators and stink bugs for increased seed yield of soybean in South-East Nigeria.



Int. J. Agric. Rural Dev., 2003, 4: 100-109