Insecticide Spray Regimes to Manage Helicoverpa armigera (Hubner) and their Impact on Natural Enemies in Cotton under High Density Planting System

Abstract

This study evaluated some new class insecticides viz., chlorantraniliprole 18.5SC, flubendiamide 480SC, spinosad 45%SC, indoxacarb 14.5SC and emamectin benzoate 5%SG in cotton under high density planting system (HDPS). These were evaluated against Helicoverpa armigera (Hubner) and their impact on natural enemies were also observed. Experiments were conducted at the ICAR-Central Institute for Cotton Research, Nagpur during 2013-14. Each of the new molecules were sprayed in eight different windows 60 days after sowing (DAS), 60 and 80 DAS, 60, 80 and 100 DAS, 60, 80 100 and120 DAS, 100 and 120 DAS, 80,100 and 120 DAS, 120 DAS and unsprayed control along with three replicates each were analysed in randomized complete block design. The damage by H. armigera was observed by counting healthy and damaged squares and bolls, and % worked out. The whole plant incidence was recorded in case of major predators sampled including spiders and coccinellids. The spray regime 2 (60 and 80 DAS), regime 3 (60, 80 and 100 DAS), regime 4 (60, 80, 100 and 120 DAS) and regime 6 (80, 100 and 120 DAS) were found superior in managing bollworms with by recording least square damage. The results on natural enemies’ populations (spiders and coccinellids) clearly revealed that, all spray regimes were more or less safe to the natural enemies. However, spray regime 1 (spray at 60 DAS), regime 2 (spray at 60 and 80 DAS) and regime 3 (spray at 60, 80 and 100 DAS) recorded maximum natural enemies. Maximum natural enemies was reported at 80 DAS in all the insecticidal spray regimes. Chlorantraniliprole, flubendiamide, spinosad, indoxacarb and emamectin benzoate through the spray regime 2 (spray at 60 and 80 DAS) was observed to be the best option against H. armigera by controlling it in early stage itself and to sustain natural enemies in the cotton ecosystem.