PRIOR EXPOSURE TO CARBARYL ALTERS BEHAVIOR OF TETRANYCHUS-URTICAE KOCH ON ACARICIDE-TREATED LEAF SURFACES

Preadult exposure to carbaryl affected the subsequent behavior of two- spotted spider mites (Tetranychus urticae Koch) on leaf surfaces with discontinuous acaricide residues. In dicofol bioassays, preexposure to carbaryl caused a loss of avoidance behavior (eliminating the tendenc y of mites to feed and stand longer off treated areas). In amitraz bio assays, preexposure to carbaryl had the opposite effect. It increased the propensity of mites to feed and stand off amitraz-treated areas, r esulting in increased avoidance of amitraz. Carbaryl preexposure there fore resulted in diametrically opposed behavioral changes in subsequen t encounters with two acaricides. These effects provide additional evi dence of the unpredictable nature of interactions between pesticides a nd show how a chemical, irrespective of degree of toxicity, can alter the behavior of arthropods in response to subsequent chemical encounte rs.