Isomer-specific comparisons of the hydrolysis of synthetic pyrethroids and their fluorogenic analogues by esterases from the cotton bollworm Helicoverpa armigera

- Assays of 22 Helicoverpa esterases against nine synthetic pyrethroid (SP) isomers and fluorogenic analogues.
- Good correlation (r = 0.7) between isomer and analogue activities.
- Some relationship between activities against different isomers and their insecticidal potency.
- Three enzymes from an SP resistant strain are not more active than their allozymes from a susceptible strain.