Selectivity of Abamectin Against Chrysoperla carnea (Stephens) (Chrysopidae, Neuroptera)

Abstract

Relative toxicities of abamectin along with spinosad, cypermethrin and chlorpyrifos currently used in cotton fields to control bollworms on the general predator, Chrysoperla carnea (Stephens) at egg, larvae and adult stages were evaluated under laboratory conditions in Tamil Nadu, India. The insecticide concentrations studied were equivalent to those prescribed for field application inclusive of various doses for abamectin. The results revealed that there was no significant adverse effect on hatchability of C. carnea caused by abamectin 1.9 EC. However, the fecundity and longevity of adults were significantly reduced at higher concentrations (2 and 2.4 ml l-1) of abamectin. The larva upon direct exposure to insecticides recorded a maximum 40.0 per cent mortality at the highest dose of abamectin (2.4 ml l-1). When the larva were fed with the insecticides treated eggs at 2.4 ml l-1, the larval mortality was 36.7 per cent and the pupation and adult emergence were 68.4 and 61.5 per cent, respectively. Abamectin at lower doses had caused very little impact upon C. carnea. All the doses of abamectin were comparatively safer than chlorpyrifos and cypermethrin. Thus, abamectin is found harmless to C. carnea and can provide selectivity in an integrated control programme for cotton bollworms.