Studies on relative toxicity of biopesticides to Helicoverpa armigera (Hubner) and Maruca vitrata (Geyer) on pigeonpea (Cajanus cajan L.)

Abstract

An experiment conducted during Kharif, 2010 to evaluate the efficacy of different biopesticides against gram pod borer Helicoverpa armigera (Hubner) and legume pod borer, Maruca vitrata (Geyer) on pigeon pea revealed that there is no significant difference between the treatments against pod damage due to gram pod borer, H. armigera since the population and thereby pod damage was very low during the season. The untreated check has recorded only 1.63% pod damage due to Helicoverpa. The per cent inflorescence damage due to legume pod borer was lowest in spinosad 45% SC @ 73 g a.i/ha (4.74%), followed by Bacillus thuringiensis-1 @ 1.5 kg/ha (10.52%) and Beauveria bassiana SC formulation @ 300mg/Lt (14.15%) with 80.9, 57.6 and 42.9 per cent reduction over control respectively as against control (24.79%). The pod damage due to Maruca was the lowest in spinosad (17.38%), followed by Bt.-1 (27.57%) and B. bassiana SC formulation @ 300 mg/lt (33.82%) as against control (45.84%) with 62.1, 39.9 and 26.2 per cent reduction over control respectively. The highest grain yield was recorded in spinosad 45% SC @ 73 g.i/ha treated plots (831.0 kg/ha), followed by Bt.1 @ 1.5 kg/ha (743.1 kg/ha) and B. bassiana SC formulation @ 300mg/Lt (694.4 kg/ha) with 104.0, 82.4 and 70.5 per cent increase over control respectively as against the minimum yield of 407.4 kg/ha in the untreated check. ©JBiopest.