Mitochondrial P-Glycoprotein ATPase Contributes to Insecticide Resistance in the Cotton Bollworm, Helicoverpa armigera (Noctuidae: Lepidoptera)
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Cotton bollworm, Helicoverpa armigera, is one of the most damaging polyphagous pests worldwide, which has developed high levels of resistance to commonly applied insecticides. Mitochondrial P-glycoprotein (Pgp) was detected in the insecticide-resistant strain of H. armigera using C219 antibodies, and its possible role was demonstrated in the efflux of xenobiotic compounds using spectrofluorometer. The TMR accumulated in mitochondria in the absence of ATP, and effluxed out in presence of ATP; the process of efflux was inhibited in the presence of ortho-vandate, an inhibitor of Pgp, in insecticide-resistant larvae of H. armigera. The mitochondria isolated from insecticide-resistant larvae were resistant to insecticide-induced inhibition of oxygen consumption and cytochrome c release. Membrane potential decreased in a dose-dependent manner in the presence of higher concentration of insecticides (>50 µM) in mitochondria of insecticide-resistant larvae. In conclusion, mitochondrial Pgp ATPase detected in the insecticide-resistant larvae influenced the efflux of xenobiotic compounds. Pgp might be involved in protecting the mitochondrial DNA and the components of the electron transport chain from damage due to insecticides, and contributing to the resistance to the deleterious effects of insecticides on the growth of insecticide-resistant H. armigera larvae.
KeywordsHelicoverpa armigera Mitochondria Multidrug resistance Pgp ATPase Insecticides
Carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone
This work was supported in part by UGC to S Md Akbar (under RFSMS scheme), UGC—SAP (DSR—I), New Delhi to KS and the Ministry of Agriculture, Government of India to HCS. We are indebted to Dr FJ Sharom, Professor, Department of Molecular and Cellular Biology, University of Guelph, Canada, for reading the manuscript before its submission and her helpful discussions in improving the manuscript.
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