The Development of Insecticide Resistance and Carboxylesterase Activity in Helicoverpa armigera (Hubner) from Kumaon Himalayas

摘要

Insecticidal susceptibility pattern of three Helicoverpa armigera (Hubner) populations collected from Kumaon Himalayan region was studied under laboratory condition by leaf residue bioassays and their midgut carboxylesterase activity was compared. The results revealed that some of the age old insecticides such as endosulfan, oxydemeton methyl, monocrotophos, deltamethrin and fenvalerate either failed or exhibited only poor toxicity against one or all three H. armigera populations tested. H. armigera collected from Pant nagar, a tarai region adjoining the Kumaon hills was found more tolerant not only against the old insecticides but also against the new molecules such as profenofos and indoxacarb. H. armigera larvae collected from Hawalbagh and Darim villages in the Kumaon hills were found highly susceptible' to dichlorvas, methyl parathion, profenofos and indoxacarb. Interestingly, the biopesticide, Bacillus thuringiensis was found highly toxic to all three H. armigera populations. Comparison of the carboxylesterase . enzyme titer of the fifth instar H. armigera midgut revealed significantly higher specific activity of the enzyme (8.54±0.75 μMoles per min per mg) in Pantnagar population as compared to other two populations. The findings here demonstrate the possible development of resistance in the geographically isolated populations of H. armigera in the Kumaon Himalayan hills and advocates cautious use of insecticides.