Anthropogenic climate change is a substantial challenge to biodiversity conservation, exerting direct effects on plants and animals alike. Herbivores may be additionally affected by indirect effects, mediated through, for instance, climate change-induced alterations in host-plant quality. Thus, climate change may pronouncedly impact long-evolved plant-animal interactions, but our knowledge is still in its infancy, particularly with regard to the combined effects of temperature and water availability. We here investigate the effects of simulated climate change, considering variation in both temperature and water availability, on (1) host-plant chemistry, (2) herbivore oviposition and larval feeding preference, and (3) larval and adult performance. As study system, we used the butterfly Pieris napi (Lepidoptera: Pieridae) and its host plant Sinapis alba (Brassicacae). Host-plant chemistry was affected by simulated climate change, with higher temperatures increasing the carbon-nitrogen ratio and concentrations of glucosinolates, while drought stress led to reduced glucosinolate concentrations. Both egg-laying females and larvae preferred plants with the highest concentrations of the glucosinolate glucosinalbin, potentially acting as oviposition and feeding stimulus. Herbivore performance was positively affected by plants grown at control temperatures or under drought stress and thus reduced glucosinolate concentrations. Hence, P. napi was not able to select the most profitable host. Our study indicates that (1) climate-induced changes in plant chemistry may exert indirect effects on herbivores, (2) effects of climate change will depend on the magnitude of change in specific abiotic parameters and their interactions, whereby positive (e.g. drought) and negative (e.g. temperature) effects may even cancel out each other, and (3) changes in critical chemical cues may diminish host-plant detectability and thereby result in reduced realised fecundity. We thus highlight the important role of temperature and water availability on plant chemistry, which may change interactions between insects and plants.

人为的气候变化是对生物多样性保护的重大挑战，对动植物均具有直接影响。草食动物还可能受到间接作用的影响，这种间接作用是由例如气候变化引起的寄主植物质量变化介导的。因此，气候变化可能会显着影响长期发展的动植物相互作用，但我们的知识仍处于起步阶段，尤其是在温度和水的有效利用方面。我们在这里研究气候变化模拟的影响，同时考虑温度和水的可利用性对（1）寄主植物化学，（2）食草动物产卵和幼虫摄食的偏好，以及（3）幼虫和成年性能的影响。作为学习系统，我们使用了蝴蝶Pieris napi（鳞翅目：Pieridae）及其寄主植物Sinapis alba（Brassicacae）。寄主植物化学物质受到模拟的气候变化的影响，较高的温度增加了碳氮比和芥子油苷的浓度，而干旱胁迫导致芥子油苷浓度降低。产卵的雌性和幼虫都优选具有最高浓度的芥子油苷的芥子油苷的植物，其可能作为产卵和喂养的刺激物。在控制温度或干旱胁迫下生长的植物对草食动物的性能有积极的影响，因此芥子油苷的浓度降低。因此，P。napi无法选择最赚钱的主机。我们的研究表明：（1）气候导致的植物化学变化可能对草食动物产生间接影响，（2）气候变化的影响将取决于特定非生物参数的变化幅度及其相互作用，从而产生积极的影响（例如干旱）和负面影响（例如温度）甚至可能相互抵消，并且（3）关键化学线索的变化可能会削弱宿主植物的可检测性，从而导致降低的繁殖力。因此，我们强调了温度和水分可用性对植物化学的重要作用，这可能会改变昆虫与植物之间的相互作用。