Persisting Resistance of Helicoverpa armigera (Lepidoptera: Noctuidae) to Pyrethroid, Organophosphate and Carbamate Insecticides

Abstract

Insecticide resistance in polyphagous pest Helicoverpa armigera is important in any agroecosystem. The resistance to classical insecticides viz., synthetic pyrethroids, organophosphates and carbamates was global issue in early nineties. Hence many new generation pesticides are in use widely. To know the status of different insecticides belonging pyrethroid, ogranophaopsahte and carbamate molecules monitoring was exercised using populations of H. armigera collected from different agroclimatic situations in Karnataka state, India. An abstinent to tremendous resistance was documented for synthetic pyrethroids, carbamates and organphosphates insecticide despite under use of these molecules over decades. Raichur populations comprehend high level of resistance to Pyrethroids with LC 50 121.63 ppm to cypermenthrin which indicated 23.21fold of resistance with respect to a laboratory susceptible strain. Similarly, there was 24.95 folds of resistance to deltamethrin in same population with LC 50 128.47 ppm. Among organophosphates a high level of resistance was recorded against monochrotophos with LC50 160.94 ppm and 18.23 resistance ratio in Rachur population itself. The same population exhibited 9.24 resistance ratio towards thiodicarb a carbamate insecticide. Kalaburagi population indicated resistance close to Raichur population against all insecticides both being high selection pressures areas. On the contrary resistance to each insecticide tested was low in Vijayapur population, a low rainfall area. The cross resistance was significant amongst similar groups and negative in a selective pattern. Quinolphos, lambda cyhalothrin and profenphos with high r = -8 to -9 appeared to be choice for rotation a resistance management strategy.