<b>CARBAMATE RESISTANCE IN</b><i>HELICOVERPA ARMIGERA</i><b>(HÜBNER) (LEPIDOPTERA: NOCTUIDAE) IN AUSTRALIA</b>

Abstract

Abstract Helicoverpa armigera larvae were collected from N.S.W. and Queensland from 1983 to 1990 and bioassayed with methomyl and thiodicarb. Methomyl was tested by topical application on 3rd instars. New bioassay techniques for thiodicarb, a stomach poison and methomyl as an ovicide were developed and are described. Baseline susceptibility data for thiodicarb are presented, as is evidence of widespread resistance to methomyl in H. armigera larvae. Resistance to methomyl in a selected strain was estimated as approximately 23 fold, while in field strains, resistance did not exceed 11 fold. Methomyl synergism by piperonyl butoxide and DBF inferred that resistance may be attributable to monooxygenase and esterase detoxification. Resistance was not expressed by the egg stage. These data are discussed with reference to the Australian Helicoverpa resistance management strategy.