Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, Palapye, Botswana.
Department of Ecology and Resource Management, University of Venda, Thohoyandou, 0950, South Africa.
Parasit Vectors. 2020 Dec 1;13(1):604. doi: 10.1186/s13071-020-04479-3.
Predators play a critical role in regulating larval mosquito prey populations in aquatic habitats. Understanding predator-prey responses to climate change-induced environmental perturbations may foster optimal efficacy in vector reduction. However, organisms may differentially respond to heterogeneous thermal environments, potentially destabilizing predator-prey trophic systems.
Here, we explored the critical thermal limits of activity (CTLs; critical thermal-maxima [CT] and minima [CT]) of key predator-prey species. We concurrently examined CTL asynchrony of two notonectid predators (Anisops sardea and Enithares chinai) and one copepod predator (Lovenula falcifera) as well as larvae of three vector mosquito species, Aedes aegypti, Anopheles quadriannulatus and Culex pipiens, across instar stages (early, 1st; intermediate, 2nd/3rd; late, 4th).
Overall, predators and prey differed significantly in CT and CT. Predators generally had lower CTLs than mosquito prey, dependent on prey instar stage and species, with first instars having the lowest CT (lowest warm tolerance), but also the lowest CT (highest cold tolerance). For predators, L. falcifera exhibited the narrowest CTLs overall, with E. chinai having the widest and A. sardea intermediate CTLs, respectively. Among prey species, the global invader Ae. aegypti consistently exhibited the highest CT, whilst differences among CT were inconsistent among prey species according to instar stage.
These results point to significant predator-prey mismatches under environmental change, potentially adversely affecting natural mosquito biocontrol given projected shifts in temperature fluctuations in the study region. The overall narrower thermal breadth of native predators relative to larval mosquito prey may reduce natural biotic resistance to pests and harmful mosquito species, with implications for population success and potentially vector capacity under global change.
捕食者在调节水生栖息地中幼虫蚊子猎物种群方面起着至关重要的作用。了解捕食者-猎物对气候变化引起的环境干扰的反应，可能会促进减少病媒的最佳效果。然而，生物体可能会对异质热环境产生不同的反应，从而潜在地破坏捕食者-猎物的营养系统。
在这里，我们探索了关键捕食者-猎物物种的活动临界热限（CTLs；临界热最大值[CT]和最小值[CT]）。我们同时检查了两种龙虱捕食者（Anisops sardea 和 Enithares chinai）和一种桡足类捕食者（Lovenula falcifera）以及三种蚊媒幼虫（埃及伊蚊、三带喙库蚊和致倦库蚊）的 CTL 异步性，跨越龄期（早期，1 龄；中期，2/3 龄；晚期，4 龄）。
总体而言，捕食者和猎物在 CT 和 CT 上存在显著差异。捕食者的 CTLs 通常低于蚊子猎物，这取决于猎物的龄期和物种，其中 1 龄幼虫的 CT 最低（最低暖耐受性），但 CT 也最低（最高冷耐受性）。对于捕食者，L. falcifera 表现出最窄的 CTLs，而 E. chinai 的 CTLs 最宽，A. sardea 的 CTLs 居中。在猎物物种中，全球入侵物种埃及伊蚊的 CT 始终最高，而根据龄期，不同猎物物种之间的 CT 差异不一致。
这些结果表明，在环境变化下，捕食者和猎物之间存在显著的不匹配，这可能会对研究区域温度波动的预测变化下的自然蚊子生物控制产生不利影响。与幼虫蚊子猎物相比，本地捕食者的整体较窄的热幅可能会降低自然生物对害虫和有害蚊子物种的抵抗力，这对全球变化下的种群成功和潜在的媒介能力有影响。
