Guarding, Aggressive Behavior, and Mating Success in Male Twospotted Spider Mites1, 2

Abstract

Males of Tetranychus urticae are attracted to quiescent ♀ deutonymphs, where they remain in attendance until the female ecdyses and mating is accomplished. Fighting may occur between males when more than one attempt to guard a single female. Aggressive encounters are characterized by considerable grappling and pushing, and may involve the use of silk to entangle and repel an opponent. Sometimes injuries are inflicted by the extruded cheliceral stylets, resulting in the death of one male. Experiments revealed the advantage of 1st discovery and of establishing dominance over other competing males before the emergence of the female. Size is also important, with larger males generally able to defeat smaller ones. During the course of a colonizing episode the functional (rather than actual) sex ratio becomes markedly skewed toward males and competition for mates is intense. Guarding and aggressive behaviors thus have important consequences for ♂ reproductive sucess.