A survey of insecticide resistance in Helicoverpa armigera in central and South Indian cotton ecosystems

Abstract

Monitoring for insecticide resistance was carried out on Helicoverpa armigera (Hubner) collected from main cotton-growing districts of Central and South India for the period 2007-2009. Four chemicals, including cyclodiene (endosulfan), organophosphate (monocrotophos) and pyrethroids (fenvalerate and cypermethrin) were tested against second-, third- and fifth-instar H. armigera larvae. Data from the replicates were pooled and dose-mortality regressions were computed by probit analysis. Resistance factors (RF) were estimated at the LD50 level as RF=LD50 field strain/LD50 susceptible strain. The Helicoverpa armigera (Hubner) exhibited widespread resistance (RF=41-700) to cypermethrin. The H. armigera strain from Coimbatore, South India exhibited highest level of resistance (700-fold) to cypermethrin and the lowest resistance (3- fold) was recorded in field strain from Akola, Central India. A substantial inter-strain variation in insecticide resistance was evident.