Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, Montana, USA.
Department of Entomology, Michigan State University, East Lansing, Michigan, USA.
Plant Cell Environ. 2024 Dec;47(12):4530-4542. doi: 10.1111/pce.15040. Epub 2024 Jul 16.
Over the last decade, a large effort has been made to understand how extreme climate events disrupt species interactions. Yet, it is unclear how these events affect plants and herbivores directly, via metabolic changes, and indirectly, via their subsequent altered interaction. We exposed common milkweed (Asclepias syriaca) and monarch caterpillars (Danaus plexippus) to control (26:14°C, day:night) or heat wave (HW) conditions (36:24°C, day:night) for 4 days and then moved each organism to a new control or HW partner to disentangle the direct and indirect effects of heat exposure on each organism. We found that the HW directly benefited plants in terms of growth and defence expression (increased latex exudation and total cardenolides) and insect her'bivores through faster larval development. Conversely, indirect HW effects caused both plant latex and total cardenolides to decrease after subsequent herbivory. Nonetheless, increasing trends of more toxic cardenolides and lower leaf nutritional quality after herbivory by HW caterpillars likely led to reduced plant damage compared to controls. Our findings reveal that indirect impacts of HWs may play a greater role in shaping plant-herbivore interactions via changes in key physiological traits, providing valuable understanding of how ecological interactions may proceed in a changing world.
在过去的十年中，人们付出了巨大的努力来理解极端气候事件如何破坏物种相互作用。然而，这些事件如何通过代谢变化直接影响植物和食草动物，以及如何通过它们随后改变的相互作用间接影响，尚不清楚。我们将普通乳草（Asclepias syriaca）和帝王蝶幼虫（Danaus plexippus）暴露于对照（26:14°C，昼夜）或热浪（HW）条件（36:24°C，昼夜）下 4 天，然后将每个生物移至新的对照或 HW 伙伴，以厘清热暴露对每个生物的直接和间接影响。我们发现，HW 直接有益于植物的生长和防御表达（增加乳状液渗出和总卡地林），并通过更快的幼虫发育使昆虫her'bivores受益。相反，在随后的食草作用之后，HW 引起的间接 HW 效应导致植物乳状液和总卡地林含量下降。尽管如此，与对照相比，HW 毛毛虫取食后，更多有毒卡地林和叶片营养质量下降的趋势可能导致植物损害减少。我们的研究结果表明，HW 的间接影响可能通过关键生理特征的变化在塑造植物-食草动物相互作用方面发挥更大的作用，为了解生态相互作用如何在不断变化的世界中进行提供了有价值的认识。
