The predatory mite Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae) is currently used as an efficient biological control agent of thrips, whiteflies and spider mites, which are economically damaging pests of ornamental plants and vegetable crops grown in greenhouses and fields worldwide. Currently, the effects of relative humidity (RH) and water availability on the optimal growth of A. swirskii are unknown. Here, we test the combined effects of different levels of RH (33%, 53%, 73% and 92%) and water availability on the development and reproduction of male and female A. swirskii feeding on the dried fruit mite, Carpoglyphus lactis (Linnaeus). While eggs failed to hatch at 33% RH, the survival rates of the immature stages at ≥ 53% RH increased solely in response to water availability and not due to changes in RH. Regarding growth and development, low RH extended the egg–adult duration and pre-oviposition period. We also found that the negative effects of low RH on fecundity were partially or completely eliminated when drinking water was available. For the life table parameters, the highest values of net reproductive rate (R₀) and intrinsic rate of natural increase (r) were achieved at the highest RH and when drinking water was available. Overall, water availability mitigated the negative effect of low RH on female reproduction, and female development was more sensitive to water availability than male development. Lastly, a comparison of similar research on A. swirskii suggested that water availability and RH are more influential on r than food source or temperature.

掠食性螨Amblyseius swirskii（Athias-Henriot）（Acari：Phytoseiidae）目前被用作蓟马，粉虱和红蜘蛛的有效生物防治剂，这些蓟马在经济上破坏了遍布全球温室和田地的观赏植物和蔬菜的害虫。目前，相对湿度（RH）和水的可用性对A. swirskii的最佳生长的影响尚不清楚。在这里，我们测试了不同水平的相对湿度（33％，53％，73％和92％）和水分利用率对以干果螨Carpoglyphus lactis为食的雄性和雌性拟南芥生长和繁殖的综合影响。（Linnaeus）。尽管卵在33％RH下未能孵化，但不成熟阶段在≥53％RH时的存活率仅因水的供应而增加，而不是由于RH的变化而增加。关于生长发育，低相对湿度延长了卵子成虫的持续时间和产卵前的时间。我们还发现，当获得饮用水时，低RH对生殖力的负面影响已部分或完全消除。对于寿命表参数，净生殖率（R ₀）和固有自然增长率（r）的最大值）是在最高RH和有饮用水的情况下实现的。总体而言，水的供应量减轻了低RH对女性生殖的负面影响，并且女性发育对水供应的敏感性高于男性发育。最后，对Swirskii进行的类似研究的比较表明，水的可利用性和相对湿度对r的影响大于食物来源或温度。