RESUMO
Aqueous leaf extracts of two plants namely Gnidia glauca Gilg. and Toddalia asiatica Lam., have been screened for their antifeedant activity against the sixth instar larvae of Helicoverpa armigera (Hbn) by applying the aqueous leaf extracts at various concentrations viz., 0.2, 0.4, 0.6, 0.8 and 1.0 percent on young tomato leaves. The larval mortality of more than 50 percent at higher concentrations (0.8 and 1.0 percent) was observed in the aqueous extracts. Among the two aqueous leaf extracts tested, T. asiatica was found to show higher rate of mortality (86.1%) at 1.0 percent concentration. A reduction in the rate of food consumption and growth was observed in the larvae of H. armigera after 48 hours of treatments in both the aqueous extracts. Since this insect pest species have developed resistance and resurgence to synthetic insecticides, the only alternate is the usage of bio-pesticides for they are eco-friendly, pollution free and easily degradable.
