This chapter presents the routes of evolution from phoresy and physogastry toward parasitism and parasitoidism, and the distribution of parasites and parasitoids among the superfamilies and families of Tarsonemina. Among the taxa of parasites and parasitoids in the superfamily Tarsonemoidea, only one adult female morph is known. However, among the all-parasitoid superfamily Pyemotoidea, only one adult female morph is known in the Acarophenacidae, but female dimorphism is recorded among at least some members of the Pyemotidae. For parasitoids, synchrony with the host phenology is vital to survival of the population because the host activity or progeny provide resources for the mites, and the young emerging winged adults are indispensable agents for the mites' disperal. Evolution toward parasitoidism appears to be correlated also with a capacity for the adult female to undergo physogastry, an immense swelling of her body while feeding on a host, before reproduction, to accommodate nearly simultaneous development of many embryos, so that they are even-aged in adulthood. Within the family Tarsonemidae, there are genera well documented as parasitoids and parasites, as well as predators. The Tarsonemina manifest various attributes that have acted in the course of evolution in favor of a diversity of symbiotic ways of life. © 1995 Academic Press Inc.
