Behavioral Response and Mortality of Nursery Populations of Two spotted Spider Mite (Acari: Tetranychidae) to Residues of Six Acaricides

Residue bioassays of six acaricides (cyhexatin, propargite, dicofol, carbophenothion, hexakis, and abamectin) were conducted against three populations of the two spotted spider mite (TSSM), Tetranychus urticae Koch. Two separate bioassays were done to examine the behavioral responses and physiological tolerance levels of the three TSSM populations to the acaricides. In a third bioassay, we determined if responses were indicative of behavior that would allow mites to disperse successfully from treated surfaces. Behavioral responses (walk-off or spin-down) significantly greater than that of the control occurred with some concentrations of hexakis, cyhexatin, and carbophenothion. Mortality of mites that walked off was very low, whereas mortality of those that spun down was high. Irritancy to four of the sixcompounds was evident in the preliminary bioassay, but successful behavioral response appeared to be directly related to the physiological tolerance levels of the mites.