Insecticide Resistance In Helicoverpa Armigera In India: Recent Developments

Seasonal changes in insecticide resistance in the cotton bollworm. Helimverpa arrnigera (Hilbner) were monitored at six widely spaced locations in lndia during 1993194 usina a discrimlnatina dose bioassay technique. lnsecticide I synergist combinations- were used to elucidate resisknce mechanisms. The status- of resistance to pyrethroids. endosulfan and omanophosphates is described and correlated with iocal farmer insecticide use slrategies.in the different regions and the role of migration in the spread of resistance beyond high input farming areas

Effect of Nucleopolyhedrovirus and Bacillus thuringiensis infection on the activity of insecticide detoxification enzymes in cotton bollworm, Helicoverpa armigera Hbn.

Enzyme assays were carried out to study the influence of Nucleopolyhedrovirus (HearNPV) and Bacillus thuringiensis subsp. kurstaki (Btk) infection on the activity levels of pesticide detoxification enzymes, viz. carboxyl esterase (CE) and mixed function oxidase (MFO) in Helicoverpa armigera . HearNPV at LC50 reduced the MFO activity by 12.0–13.5% and CE activity by 14.88–15.25% at 96 hours after treatment. Btk at LC50 reduced the MFO activity by 4.17–4.27% and CE activity by 5.77–6.55%. The joint application of HearNPV and cypermethrin at LC50 +LC50 resulted in suppression of MFO activity by 15.08–17.35% and CE activity by 16.39–17.30%. Combined treatment of Btk and cypermethrin resulted in suppression of MFO by 4.24–6.72 and CE by 8.42–8.97%, respectively