Effects of host-plant quality on male two-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 using 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 low-chlorophyll (LC) leaves had been infested for >21 days. Three parameters of male T. urticae guarding behavior were quantified: approach arrestment, and arrestment duration. HC males approached quiescent deutonymphs more often than did LC males, even though host quality of females 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. However, a different pattern was observed for arrestment duration. HC males were arrested for twice as long by LC quiescent deutonymphs than by HC females, while the LC-male arrestment durations elicited by HC and LC females did not differ. These results show that host-plant quality affects T. urticae intersexual communication, in terms of both the female signal and the male response. Whether the differing male responses observed in this study indicate alternative T. urticae mating strategies or are incidental by-products of host-induced physiological changes remains to be determined.