Insensitivity of the Acetylcholinesterase from the Organophosphate-Resistant Kanzawa Spider Mite, Tetranychus kanzawai KISHIDA (Acarina : Tetranychidae), to Organophosphorus and Carbamate Insecticides

The AChE of susceptible and OP-resistant strains of the Kanzawa spider mite was examined for resistance and sensitivity to OPs and carbamates. The selection procedure resulted in almost similar end response levels to OPs and carbamates in the selected strains, and a correlation between the low AChE activity and resistance was observed. In each of the strains the activity was slightly lower toward acetylthiocholine than toward acetylcholine. Homogeneity of sensitivity of the AChE to Ops and carbamates was recognized both in the susceptible and resistant mite. Generally, a good correlation was recognized between in vivo resistance to toxicants and in vitro insensitivity of the AChE to corresponding inhibitors, while no correlation was recognized to malaoxon, indicating the involvement of detoxification in resistance to malathion in resistant mite.