BIOEFFICACY OF NEEM KERNEL AQUEOUS EXTRACT (NKAE) AGAINST TEA RED SPIDER MITE, OLIGONYCHUS COFFEAE, NIETNER AND ITS EFFECT ON STETHORUS GILVIFRONS MULSANT, A POTENTIAL PREDATOR OF RED SPIDER MITE

Abstract

Neem kernel aqueous extract (NKAE) was evaluated at different concentrations (1-10%) against red spider mite, Oligonychus coffeae under laboratory and field conditions. Also the impact of NKAE on survival of Stethorus gilvifrons, a potential predator of red spider mite was studied. Parameters assessed were ovicidal and acaricidal activities, adult emergence, oviposition deterrent in case of red spider mite and larval & adult mortality and adult emergence for the predator. Significant ovicidal activity was exhibited at higher concentrations (6-10%). Nymphs were more susceptible to NKAE than adults. Higher concentrations (6-10%) showed 53-95% mortality of mite population under laboratory conditions. LC50 values of NKAE for nymph and adult red spider mite were found to be 47.73 mg/ml and 66.02mg/ml respectively after 24h of treatment. Field evaluation however exhibited 43-69% reduction of mite population at 6-10% concentrations. Egg laying by tea red spider mite on the NKAE treated tea leaf surface was significantly decreased (1.16-1.50 eggs/female/day) than control (3.83 eggs/female/day). Significant reduction in adult emergence (20.0-56.7%) and increased duration of total developmental period (1.00-4.33 days) were noticed at higher concentrations (4-10%) only. However, the application of NKAE on different life stages of S. gilvifrons showed no adverse effect in respect of their growth and development.