Insensitive Acetylcholinesterase and Resistance to Thiodicarb in Australian Helicoverpa armigera Hübner (Lepidoptera: Noctuidae)

Thiodicarb resistance was diagnosed in a field strain of Helicoverpa armigera from Tamworth, New South Wales in March 1993. This is the first record of H. armigera resistance to thiodicarb. Bioassays after selection in the laboratory indicated that the thiodicarb resistance factor was greater than 40-fold and was associated with cross resistance to methomyl. Insensitive acetylcholinesterase was identified as a resistance mechanism. Potential resistance management tactics and opportunities for biochemical resistance monitoring are discussed.