Effects of insecticides on the rice gall midge,Orseolia oryzaeand its parasite,Platygaster oryzae

The efficacy of certain insecticides for controlling the rice gall midge, Orseolia oryzae (Wood‐Mason), and their effects on a hymenopteran parasite of the midge, Platygaster oryzae (Cameron), have been investigated. Field trials were carried out at Chiplima, India during the wet seasons of 1980 and 1981. A seedling root dip of either chlorpyrifos or isofenphos at 0.02% a.i. for 12 h, followed by one application of ethoprophos granules at 1 kg a.i./ha 30 d.a.t. gave good control of the midge, with an average incidence of only 5.1% silver shoots, and a yield of 3935 and 3840 kg/ha of paddy rice in 1980 and 1981 respectively. Granular carbofuran, isofenphos, phorate and quinalphos were almost as effective. Insecticidal treatment in general had very little effect on P. oryzae but granular isofenphos was found to be least toxic to the parasite, permitting 22.8 to 32.7% parasitisation at 50 d.a.t.