Comparative studies on the toxicity of selected Acaricides to susceptible and resistant strains of Tetranychus urticae Koch (Acarina : Tetranychidae)

Abstract

Although scientific knowledge on insect resistance to chemicals has advanced spectacularly during the last few years it is not possible to apply directly these findings to resistance within the order Acarina. Not only are the biochemical mechanisms of acaricidal action not known with any degree of certainty, but the range of chemicals available for effective control of mites is much greater than with insects. This creates more difficulty in quantitatively forecasting likely control, development of resistance and cross resistance patterns. The object of this theses was to investigate the toxicology of a range of chemicals with Tetranychus urticae Koch and to determine cross tolerances in a Systox resistant strain. A further aspect of the work was to use a topical application bioassay methods in determining dosage-mortality data so that the methods could be examined and adjudged for quantitative resistance work on mites.