Gynaeseius liturivorus (Ehara) (Acari: Phytoseiidae) is a promising biological control agent for tiny arthropod pests, including Thrips tabaci Lindeman (Thysanoptera: Thripidae) known as a major pest of Welsh onion. In fields during summer, G. liturivorus is observed on soybean, but not on Welsh onion, even when numerous T. tabaci are present. To elucidate G. liturivorus’s occurrence on soybean and Welsh onion in relation to relative humidity (RH), we examined its egg hatching on their seedlings under low RH conditions. Then we estimated the moisture transpiration from both plants. Egg hatching occurred only on soybean plants exhibiting greater moisture transpiration. Aiming at utilizing G. liturivorus as a biological control agent for Welsh onion production in summer, evaluation of its relative tolerance and compensation potential for drought injury is necessary. Therefore, we used five phytoseiid species including G. liturivorus and Neoseiulus californicus to estimate the RH and vapor pressure deficit (VPD) at which 50% of eggs hatch (RH₅₀ and VPD₅₀). Furthermore, we examined G. liturivorus and N. californicus egg hatching under different RH oscillation conditions. Results show G. liturivorus as the most drought-sensitive among the five species tested, but G. liturivorus is able to compensate for lethal low-RH effects on egg hatching in part by periodic exposure to high RH conditions, as observed for N. californicus.

Gynaeseius liturivorus（Ehara）（Acari：Phytoseiidae）是一种有希望的生物控制剂，可用于微小的节肢动物害虫，包括被称为威尔士洋葱的主要害虫的Thrips tabaci Lindeman（Thysanoptera：Thripidae）。在夏季的田间，即使存在大量的烟粉虱，在大豆上也可以观察到石蕊蘑菇，但在威尔士洋葱上却没有。为了阐明G. liturivorus在大豆和威尔士洋葱上的相对湿度（RH）的相关性，我们研究了在低RH条件下它们在其幼苗上的卵孵化情况。然后，我们估算了两种植物的水分蒸腾作用。卵孵化仅发生在表现出更高水分蒸腾作用的大豆植株上。旨在利用石lit作为夏季大葱生产的生物防治剂，有必要评估其相对耐受性和干旱损害的补偿潜力。因此，我们使用了包括斜纹夜蛾和加利福尼亚新孢子虫在内的五种植物拟南芥属物种来估计50％卵孵化时的RH和蒸气压亏缺（VPD）（RH ₅₀和VPD ₅₀）。此外，我们检查了在不同的RH振荡条件下的G. liturivorus和N. californicus卵孵化。结果显示，在测试的五个物种中，石蕊蘑菇对干旱最敏感，但是石蕊蘑菇如对加利福尼亚猪笼草所观察到的那样，通过定期暴露于高RH条件下，能够部分降低对卵孵化的致命低RH影响。