Ambulatory and Aerial Dispersal Among Specialist and Generalist Predatory Mites (Acari: Phytoseiidae)

Predator-prey systems having a specialist predator often are over-exploitive, unstable and transient while similar systems having a generalist predator show less ßuctuation, more stability and regulation of prey at lower densities. These population dynamics also affect dispersal patterns between specialist and generalist predators. In this study, ambulatory and aerial dispersal were assessed for Þve predaceous phytoseiid mites having different degrees of predation specialization: Phytoseiulus persimilis Athias-Henriot, Specialist I; Neoseiulus fallacis (Garman) Specialist II; N. californicus Chant, Specialist II/Generalist III; Kampimodromus aberrans (Oudemans), Generalist III; and Euseius finlandicus (Oudemans), Generalist IV. In general, specialist species had more walking activity and aerial dispersal than generalist species. Somewhat different dispersal strategies were seen between N. fallacis and N. californicus. Dispersal from a prey (twospotted spider mite, Tetranychus urticae Koch) patch was earlier for the more generalized N. californicus, and N. fallacis (more specialized phytoseiid) remained without dispersing until almost all prey were eliminated. Both dispersed aerially at similar rates. In general, cues from spider mite infestations decreased dispersal of specialist phytoseiids, but either acted to increase or not affect dispersal of generalist feeding phytoseiid species.