Nest Sanitation in Social Spider Mites: Interspecific Differences in Defecation Behavior

Nest sanitation behavior is an important adaptation in nest‐building animals. The social spider mite Stigmaeopsis miscanthi (Saito) constructs woven nests on the leaf undersurface of perennial pampas grass (Miscanthus sinensis Anderss) and lives in the nests in large groups. Nest members of this species defecate at only one site inside the nest for nest sanitation, and the waste management is maintained by volatile chemical and tactile cues. Other members of the genus Stigmaeopsis Banks also construct woven nests, live in groups, and manage their fecal wastes, but the species differ in nest and group size, host plant, and social behavior. We investigated the details of waste management in four Stigmaeopsis spp. and found differences in the location of the defecation site and in the way each species recognizes this site. Like S. miscanthi, Stigmaeopsis longus defecates at only one site and uses volatile chemical and tactile cues, whereas Stigmaeopsis takahashii and Stigmaeopsis saharai both defecate at two sites and use only tactile cues. We discuss the reasons for the waste management differences within the genus, and the relationship between the means of waste management, nest and group size.