ESTERASES AND ESFENVALERATE RESISTANCE IN AUSTRALIAN HELICOVERPA-ARMIGERA (HUBNER) LEPIDOPTERA, NOCTUIDAE

Larvae of pyrethroid-resistant Australian Helicoverpa armigera have en hanced esterase activity which is due to increased production of the e nzymes. The most resistant individuals have approximately a 50-fold in crease in esterase activity compared to susceptible populations. Resis tant H. armigera have additional esterase bands which are not detected in susceptible individuals. increased esterase hydrolysis of 1-naphth yl acetate was correlated to the esfenvalerate resistance factor. Este rase bound readily to esfenvalerate. Homogenates of resistant insects hydrolyzed esfenvalerate and it is also likely that there was signific ant detoxification by sequestration. The prospect of biochemical assay s for pyrethroid resistance and the possible genetic basis of the este rase resistance mechanism are discussed. (C) 1996 Academic Press. Inc.