EFFECTS OF HOST-PLANT QUALITY ON MALE 2-SPOTTED SPIDER-MITE (ACARI, TETRANYCHIDAE) MATE LOCATION AND GUARDING BEHAVIOR

Effects of host-plant quality on two-spotted spider mite, Tetranychus urticae Koch, mate location and guarding behaviors were described usin g a no-choice bioassay. Males and quiescent deutonymphs were collected from lima bean leaves of one of two host qualities. High-chlorophyll (HC) leaves had been infested with spider mites for 6-10 days, while l ow-chlorophyll (LC) leaves had been infested for > 21 days. Three para meters of male T. urticae guarding behavior were quantified: approach arrestment, and arrestment duration. HC males approached quiescent deu tonymphs more often than did LC males, even though host quality of fem ales had no effect on male approach frequency. HC males were arrested more frequently by HC quiescent deutonymphs than were LC males, while LC males were arrested more often by LC females than were HC males. Ho wever, a different pattern was observed for arrestment duration. HC ma les were arrested for twice as long by LC quiescent deutonymphs than b y HC females, while the LC-male arrestment durations elicited by HC an d LC females did not differ. These results show that host-plant qualit y affects T. urticae intersexual communication, in terms of both the f emale signal and the male response. Whether the differing male respons es observed in this study indicate alternative T. urticae mating strat egies or are incidental by-products of host-induced physiological chan ges remains to be determined.