Resistance selection and molecular mechanisms of cypermethrin resistance in red hairy caterpillar (Amsacta albistriga walker)

• Cypermethrin evidences an elevated insecticidal activity against A. albistriga.
• LD50 of this compound for A. albistriga increased by 21.5-fold by selection.
• High activity of MFO and esterase levels found in cypermethrin selection.
• Increased esterase bands observed in resistant strain than susceptible strain.
• High expression of CYP4M44 found in resistant strain.

Amsacta albistriga is one of the important pests of oilseed crops in India. This pest has developed high resistance to organophosphate (OP) insecticide in field. Therefore, cypermethrin insecticide was used as an alternative for this pest. After 20 generations of selection with cypermethrin, the LD50 value for A. albistriga was increased by 21.5-folds. The synergism ratio of piperonyl butoxide (PBO) and triphenyl phosphate (TPP) was increased by 10- and 9.6-fold in resistant strains and comparatively, 3.9 and 4.2-fold in susceptible strains. Detoxification enzyme analysis and native PAGE electrophoresis of esterase isoenzyme further revealed that esterase and mixed function oxidase may be involved in cypermethrin resistance in CypRes strain. In addition to enzyme analysis overexpression of CYP4M44, CYP9A77 and CYP6B47 (ortholog) can confer metabolic resistance in the CypRes strain. These data provide a foundation for further study of cypermethrin resistance mechanism observed in A. albistriga.

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