Effects of starvation and humidity on the development and survival of Amblyseius swirskii, Agistemus exsertus and Amblyseius eharai

The ability of predatory mites to endure starvation or low humidity is very important for them to maintain their populations in unfavorable environments. The effects of starvation and humidity on the development and survival of Amblyseius (Typhlodromips) swirskii, Amblyseius eharai and Agistemus exsertus were studied in the laboratory. The results showed that most eggs of A. eharai and A. exsertus could not hatch at relative humidities (RH) lower than 60%. Only A. swirskii larvae could develop into protonymph stage without prey at 60– 100%RH among three species. When the prey was absent, protonymphs or gravid females of A. swirskii survived significantly longer than those of A. eharai at 60–100%RH, respectively. Furthermore, at lower humidities (60–70%RH) similar case was observed in the virgin female stage. In addition, nymphs and females of the two phytoseiid mites survived significantly longer than those of A. exsertus at 60–100%RH. It indicated that A. swirskii might be a stronger competitor relative to A. eharai or A. exsertus under starvation and low humidity conditions.