SHORT-DISTANCE LOCATION OF SPIDER-MITE COLONIES BY 3 PREDATORY MITES (ACARI, TETRANYCHIDAE, PHYTOSEIIDAE) - PREDATOR RESPONSES TO PREY-ASSOCIATED AND PREDATOR-ASSOCIATED STIMULI

Behavioral responses of the phytoseiid predators Phytoseiulus persimilis Athias-Henriot, Typhlodromus (=Metaseiulus) occidentalis Nesbitt, and Amblyseius andersoni Chant (Acari: Phytoseiidae) to the presence or absence of stimuli associated with the twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) and conspecific predators were studied in the laboratory using choice tests. Over a distance of 18-36 mm, slightly more starved females of P. persimilis selected rose leaf disks that had been infested with T. urticae than uninfested ones, whereas starved females of T. occidentalis and A. andersoni showed no preference. All three predator species eventually aggregated on the infested leaf disks, although T. occidentalis responded more slowly than P. persimilis and A. andersoni, and A. andersoni had shorter residence time in prey colonies than did the other two species. More predators of all three species chose the branch of a Y-form runway that had been previously exposed to twospotted spider mites than the unexposed branch. More P. persimilis and T. occidentalis chose the branch of the runway that had been previously exposed to conspecific predators than the unexposed one, whereas A. andersoni showed no preference. This comparative study concludes that (1) there are interspecific variations in foraging responses of phytoseiids to prey- and predator-associated stimuli, (2) aggregation of predators in prey colonies is primarily the result of arrestment rather than attraction, and (3) the intrapatch movement of some phytoseiid species among spider mite colonies is not random.