Efficacy of microbial insecticides and their combinations against Helicoverpa armigera (Hübner) on chickpea

A field experiment was conducted at Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola, to study the performance of microbial insecticides either alone or in combination against Helicoverpa armigera on chickpea for two consecutive post-rainy seasons in 2003–04 and 2004–05. Amongst the treatments, spinosad (0.01%) was most efficacious and recorded the lowest larval population and highest grain yield. Other effective microbial insecticides were HaNPV (250LE ha⁻¹) and Bt (750ml ha⁻¹), which stood only next to endosulfan (0.06%). Metarhizium anisopliae (2.5kg ha⁻¹) and Beauveria hassiana (2.5kg ha⁻¹) were less efficacious, but performed better than their combinations with either HaNPV or Bt and combination of HaNPV with Bt at reduced doses. Analysis of incremental cost-benefit ratio showed that endosulfan was the most economical treatment, followed by HaNPV, Bt and HaNPV + Bt.