Rates of development, survival and predation of immature stages of Phytoseiulus longipes (Acari : Mesostigmata : Phytoseiidae)

Larvae of Phytoseiulus longipes do not feed. Thus, the purpose of this rese arch was to determine the functional response as well as developmental and survival rates of the nymphal stages of this predator on the egg stage of t he prey Tetranychus pacificus. The egg consumption for both immature stages increased smoothly with a negative rate reaching a plateau (type II respon se). To complete their development, the protonymphs and deutonymphs consume d mean minimums of 3.15 and 3.56 eggs, respectively, at a prey density of 2 0 per excised leaf arena. The mean daily developmental and survival rates a lso showed a curvilinear rise to a plateau. These plateaus for both develop mental (71%) and survival rates (100%) were obtained at a prey egg density of 20 for both nymphal stages. Attack coefficients and handling times for b oth predator stages were estimated using several curve fitting models. All these models indicated a higher value of attack coefficient and a lower val ue of handling time for deutonymphs as compared to protonymphs. These findi ngs, combined with the knowledge of adults' predation response, foraging be haviour and prey preference, indicate this predator's overall potential as a biological control agent against web-spinning spider mites such as the Pa cific spider mite.