Esterase Inhibitors Restore Pyrethroid Susceptibility in Australian Helicoverpa armigera
Feb 14, 2019
Pyrethroid resistance in Australian Helicoverpa armigera field populations is primarily a consequence of the over production of esterase isoenzymes that metabolize and possibly sequester pyrethroid insecticides. Biochemical studies show that organophosphorous compounds inhibit pyrethroid resistance associated esterases in H. armigera. Esterase inhibition by organophosphates does not occur immediately after dosage, but occurs rapidly, with maximum enzyme inhibition from 2 to 24h after dosage, depending on the inhibitor used. These enzyme inhibition studies are supported by pyrethroid bioassays using organophosphate synergists, showing excellent levels of pyrethroid synergism against resistant H. armigera. One hundred percent mortality could be achieved when H. armigera were dosed with pyrethroid, during the time of maximum organophosphate induced enzyme inhibition. Use of organophosphate synergists in the field may have the potential to restore some pyrethroid susceptibility in Australian H. armigera.