Climate change models predict that the frequency, intensity and duration of heat waves will increase in the next decades. Heat waves can have profound impact on the reproduction of biocontrol agents ranging from postponing oviposition to manipulating offspring quantity via egg number and quality via egg size. Such species-specific responses of biocontrol agents to heat stress may also affect their success in controlling the target pest. Here, we evaluated the predation and reproductive performance of the two spider mite predators Phytoseiulus persimilis and Neoseiulus womersleyi exposed to simulated mild, moderate and extreme heat wave conditions over three days. Irrespective of heat wave conditions, all N. womersleyi females survived, whereas 12% of the P. persimilis females died. Both species responded to heat stress via plastic modifications resulting in increased predation rates and smaller egg sizes. Significantly more P. persimilis females postponed oviposition during the experimental phase than N. womersleyi. The deposited egg number of Phytoseiulus persimilis was not affected by heat wave conditions. On the contrary, the reproductive output of N. womersleyi was a function of temperature, i.e., the higher the temperature, the higher the number of deposited eggs. These findings indicate that P. persimilis is more heat sensitive in relation to reproduction than N. womersleyi. However, further investigations of heat wave effects on other fitness-related traits and their consequences at population level are needed to find out whether N. womersleyi is an alternative or supplement to P. persimilis as spider mite control agent under heat waves.

气候变化模型预测，未来几十年热浪的频率、强度和持续时间将增加。热浪可以对生物防治剂的繁殖产生深远的影响，从推迟产卵到通过卵数控制后代数量和通过卵大小控制质量。生物防治剂对热应激的这种物种特异性反应也可能影响它们控制目标害虫的成功。在这里，我们评估了在三天内暴露于模拟的轻度、中度和极端热浪条件下的两种蜘蛛螨捕食者Phytoseiulus persimilis和Neoseiulus womersleyi的捕食和繁殖性能。不管热浪条件如何，所有的N. womersleyi雌性都存活了下来，而 12% 的P. persimilis雌性死亡。两种物种都通过塑料改性对热应激做出反应，从而导致捕食率增加和鸡蛋尺寸变小。在实验阶段，比N. womersleyi推迟产卵的P. persimilis雌性明显更多。Phytoseiulus persimilis 的产卵数不受热浪条件的影响。相反，N. womersleyi的繁殖产量是温度的函数，即温度越高，产卵数量越多。这些发现表明P. persimilis在繁殖方面比N. womersleyi对热更敏感. 然而，需要进一步研究热浪对其他健康相关性状的影响及其在种群水平上的后果，以确定N. womersleyi是否是P. persimilis的替代品或补充品，作为热浪下的红蜘蛛控制剂。