COMPARATIVE BASELINE RESISTANCE OF SPODOPTERA LITURA AND HELICOVERPA ARMIGERA TO INSECTICIDES ON TOBACCO

Abstract

In view of a shift in the use of pesticides on tobacco in consonance with growing concern on pesticide residues, baseline resistance data of two lepidopteran pests of tobacco viz., S. litura and H. armigera have been generated against select insecticides. Bio-assays as per the Insecticide Resistance Action Committee (IRAC) was followed. Among the insecticides tested for toxicity against S. litura through stomach action, the lowest LC50 value was recorded with emamectin benzoate followed by rynaxypyr and the growth regulator novaluron. Out of the eleven insecticides with stomach action against which base line resistance data of H. armigera were generated, the lowest LC50 value was recorded with emamectin benzoate followed by indoxacard, spinosad and rynaxypyr establishing their efficacy at very low concentrations. The comparison of baseline resistance of S. litura from East Godavari and Guntur districts of Andhra Pradesh revealed that Guntur population recorded 7.09, 1.27, 1.44, 2.57, 1.65 and 2.68 times higher LC50 values for novaluron, spinosad, acephate, indoxacarb, emamectin benzoate and endosulfan respectively compared to Rajahmundry population. The Guntur population of H. armigera recorded 1.41, 1.33, 1.08, 33.06, 12.08, 1.41, 1.21 and 1.14 times higher LC50 values of novaluron, thiodicarb, fipronil, rynaxypyr, acephate, hlorpyriphos, endosulfan and flubendiamide respectively compared to Rajahmundry population when tested for stomach action.