Management of sorghum army worm, Mythimna separata (Walker) (Lepidoptera: Noctuidae) using biopesticides

A field experiment was conducted for two years (2002–03 and 2003–04) to manage armyworm, Mythimna separata (Walker), on sorghum with biopesticides, viz., Nomuraea rileyi (Farlow) Samson and MsNPV, and compared with poison bait and chemical control, Spray of N. rileyi at both the doses, viz., 1 x 10⁵ and 2 x 10⁸ conidia l⁻¹, were found to be effective in checking the larval population. The highest yield of 21.14 q ha⁻¹ was obtained in N. rileyi spray at 2 x 10⁸ conidia I⁻¹ and was on par with N. rileyi spray at 1 x 10⁸ conidia I⁻¹. The maximum cost-benefit ratio of 1: 36.45 was obtained in N, rileyi spray at 1 x 10⁸ conidia I⁻¹ followed by N. rileyi spray at 2 x 10⁸ conidia I⁻¹ with a CB ratio of 1: 29.44.