Complex interactions in biological control

生物防治是利用天敌(病原体、寄生虫和捕食者)来抑制害虫种群。它是合成杀虫剂的一种可行和可持续的替代品。然而，许多生物和非生物因素可能会影响生防剂的效果。我的研究旨在确定节肢动物群落内多物种相互作用的一些主导生态学原理和机制。这项研究既重要又及时，因为越来越多的生防剂可用于农业。此外，气候变化可能会损害生物防治。 气温上升和极端气候事件的增加不仅影响物种的表现，也影响物种之间的相互作用。气候变化预计将通过改变(I)害虫和天敌之间的相对代谢率和相关过程(例如，发育、觅食、繁殖)，以及(Ii)生防剂和害虫的空间和时间同步性，直接影响生物防治。利用不同的捕食者-寄生蜂模型，以及我和我的学生最近收集的关于生防剂温度反应的大量数据集，我们建议研究(I)温度介导的新陈代谢变化，特别是在低温和高温下，如何影响天敌的觅食行为和繁殖，从而确定它们对害虫种群的自上而下的影响，以及(Ii)害虫及其天敌之间潜在的物候不匹配如何限制生物防治-通过使用一种指数来识别容易受到气候变化破坏的猎物/宿主-捕食者/寄生虫关系。 我的程序的第二个轴与寄生蜂利用寄主进化的策略有关，更具体地说，是它们操纵寄主行为的能力。我希望研究从最近的和最终的机制到生态后果，一种在很大程度上没有被探索的宿主操纵：保镖操纵。我们观察到，寄生黄蜂有能力将其瓢虫宿主转变为保镖，同时在其茧内发育，这导致对正在发育的寄生虫的捕食显著减少。此外，出人意料的是，瓢虫可能会从寄生中恢复过来。我计划首先通过进行实地工作来量化寄生蜂自然历史的不同方面，以提高我们对其宿主专一性、季节生态学和在农业生态系统中的作用的了解。接下来，我想回答两个关于寄生瓢虫生态属性的重要问题。首先，寄生在多大程度上损害了瓢虫的表现？其次，从应用的角度来看，在田间条件下，寄生的瓢虫与未寄生的同种瓢虫具有本质上相同的调节蚜虫种群的能力吗？

Biological control is the use of natural enemies (pathogens, parasites and predators) to suppress pest populations. It is a viable and sustainable alternative to synthetic pesticides. However, numerous biotic and abiotic factors may influence the effectiveness of biocontrol agents. My research is aimed at identifying some of the governing ecological principles and mechanisms of multispecies interactions within arthropod communities. This research is both essential and timely, for an increasing number of biocontrol agents are available in agriculture. Furthermore, climate change may compromise biological control. Rising temperatures and increasing extreme climatic events not only affect species performance, but also species interactions. Climate change is expected to directly affect biological control by modifying (i) the relative metabolic rate and associated processes (e.g., development, foraging, reproduction) between pest and natural enemies, and (ii) both the spatial and temporal synchrony of biocontrol agents and pests. Using different predator-parasitoid models, as well as a large data set on thermal responses of biological control agents my students and I have recently collected, we propose to examine (i) how temperature-mediated metabolic changes, especially at low and high temperatures, influence the foraging behaviour and reproduction of natural enemies and thereby determine their top-down effect on pest populations, and (ii) how potential phenological mismatching between pests and their natural enemies can limit biological control - through the use of an index that identifies prey/host-predator/parasite relationships that are susceptible to be disrupted by climate change. A second axis of my program relates to strategies evolved by parasitic wasps to exploit their host, more specifically their ability to manipulate host behaviour. I wish to study, from proximate and ultimate mechanisms to ecological consequences, a type of host manipulation that has been largely unexplored: the bodyguard manipulation. We observed that a parasitic wasp has the capacity to transform its ladybird host into a bodyguard while developing within its cocoon, which results in a significant reduction in predation on the developing parasite. Furthermore, and unexpectedly, ladybirds may recover from parasitism. I plan to first quantify different aspects of the natural history of the parasitic wasp by conducting field work to improve our understanding of its host specificity, seasonal ecology and role in agroecosystems. Next, I wish to answer two important questions on the ecological attributes of parasitized ladybirds. First, to what extent does parasitism impair ladybird performance? Second, from an applied perspective, do parasitized ladybirds have intrinsically the same capacity to regulate aphid populations as unparasitized conspecifics under field conditions?