Bioefficacy of rynaxypyr and spinosad against green semilooper, Chrysodeixis acuta walker on soybean

Four insecticides Le. Rynaxypyr 20 SC @ 100 and 150 ml/ha, Spinosad 45 SC @ 125, 162.5 and 187.5 ml/ha, Methomyl 40 SP 1.0 kg/ha and Triazophos 40 EC @ 800 ml/ha were evaluated for their efficacy against green semilooper Chrysodeixis acuta Walker (Noctuidae: Lepidoptera) at Agricultural Research Station, Ummedganj, Kota (Rajasthan) during kharif 2007 and kharif 2008. The pooled larval population of green semilooper varied from 0.46 to 3.38 per metre row length (mrl) and all the treatments were significantly superior over control in reducing the pest population. However, minimum larval population (0.46 larva/mrl) was observed with Methomyl 40 SP @ 1.0 kg/ha followed by Spinosad 45 SC @187.5 ml/ha (0.50 larva/mrl) as compared to untreated control (3.38 larvae/mrl). The seed yield of soybean varied from 952 to 1106 kg/ha in different treatments as compared to untreated control (813 kg/ha) and among the treatments, Rynaxypyr 20 SC @ 100 ml/ha and Triazophos 40 EC @ 800 ml/ha gave maximum seed yield (1106 kg). The maximum net return with highest IBCR (19.82) was obtained with Triazophos 40 EC @ 800 ml/ha followed by Rynaxypyr 20 SC @ 100 ml/ha.