Abstract

Intra- and interspecific predation was examined for adult females of the generalist phytoseiid mites Amblyseius andersoni and Neoseiulus californicus. For both species, gravid females were placed singly in cages. After 24 h starvation, eggs, newly hatched larvae, or protonymphs of con- or heterospecifics were added into each cage. Experiments were performed under laboratory conditions at 25±2 ˚C, 75% RH and a photoperiod of 16h light: 8h dark. Predation rates and oviposition were recorded every 24 h for 10 consecutive days. Each treatment (con- or heterospecific prey) was replicated 20 times for each prey-species. Adult females of N. californicus had significantly higher predation on conspecific than heterospecific eggs but consumed similar amounts of con- and heterospecific larvae and protonymphs. Oviposition was significantly higher when feeding on heterospecific larvae (0.15 eggs per female per day) than conspecific (0.01 eggs per female per day). Female of A. andersoni had higher predation on heterospecific larvae (0.87 larvae per female per day) than conspecific larvae (0.44 larvae per female per day). Predation rate of adult females of A.andersoni had no significant difference when fed on con- and heterospecific eggs and protonymphs. Also oviposition of these females had no significant difference when fed on con- and heterospecific larvae and protonymphs. Females of A. andersoni had about two times higher oviposition rate when fed on heterospecific eggs comparing with conspecifics eggs (0.07 vs. 0.03 egge/female/day). It seems that the larvae of A. andersoni had more nutritional value than conspesific larvae for gravid N. californicus females and this female laid more eggs when fed on heterospecific larvae. But for A. andersoni gravid females the eggs of N. californicus had more nutritional value than conspesific eggs.