Variation in counterattack effect against a phytoseiid predator between two forms of the social spider mite, Stigmaeopsis miscanthi

摘要

In Japan, Stigmaeopsis miscanthi (Saito) occurs in two forms that are differentiated by the intensity of male-to-male aggression, i.e. there is a low aggression and a high aggression group (known as the LW and HG forms, respectively). The effects of counterattack behavior against predators were experimentally compared between the two forms. Parental males and females of both forms could achieve significant counterattack success against Typhlodromus bambusae, a specific predator, and counterattack efficiency increased significantly with parental density. Furthermore, the HG form showed a stronger tendency than the LW form to kill predator larvae. Thus, variation in counterattack success may exist between these two forms, and there is some correspondence between male-to-male belligerence and counterattack effectiveness against predators.