Female mating strategy during precopulatory mate guarding in spider mites

In some taxa, females choose their mates indirectly by using male combat. In the Kanzawa spider mite, Tetranychus kanzawai, adult males guard prereproductive quiescent females. In a dual choice experiment, more males first approached females already guarded by a conspecific male than approached solitary females. In further experiments, I examined which factors attracted males during precopulatory mate guarding. Males were not attracted to males not in a mate-guarding position. In contrast, the presence of a nonbreeding individual, a juvenile male or a female in a mate-guarding position did attract conspecific males. These results suggest that the presence of any conspecific individual in a mate-guarding position stimulates quiescent females to produce chemicals that attract males. Guarded quiescent females also attracted the attention of the predatory mite, Neoseiulus womersleyi, but solitary females did not. Since N. womersleyi search for prey using chemical cues, guarded females that release more chemicals than solitary females are probably in more danger. However, males were not attracted to guarded quiescent females that had been previously exposed to N. womersleyi. Thus, quiescent females appeared to control the release of their chemicals, that is, guarded quiescent females release a male-attractant signal. When more than one male attempts to guard one female, male combat often occurs. I discuss the possibility of indirect mate choice by T. kanzawai females during precopulatory mate guarding facilitated by the use of male-attractant signals.