Hunger and age effects on searching behavior of three species of predatory mites (Acari: Phytoseiidae)

Abstract

The effects of hunger level and adult age on searching behavior by the predatory mites, Phytoseiulus persimilis Athias-Henriot, Typhlodromus (= Metaseiulus) occidentalis Nesbitt, and Amblyseius andersoni (Chant), in patches of the twospotted spider mite, Tetranychus urticae Koch, were studied in the laboratory by continuous observation. Foraging responses such as patch giving-up time, patch time, and searching efficiency by female predators were affected strongly by hunger level and weakly by age; in some responses, the effects of hunger level changed with age. Effects of hunger level and age on various responses differed among predator species. In spite of the interspecific variation, starvation generally increased predator giving-up time and thus increased the duration of patch visits. Total patch time was correlated with the duration of visits rather than the number of visits. Predators that spent more time in prey patches also encountered and attacked more prey. Prey encounters and attacks increased patch time by an increment in time as a result of prey handling and by increasing the giving-up time. With successive visits to the prey patch, the strength of predator responses waned either because of habituation to patch cues or because of satiation after feeding. Host plant influence on predator behavior was stronger in the generalist A. andersoni than in the specialist P. persimilis.