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。它是合成农药的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物防治剂的有效性。我的研究旨在确定一些管理生态学原则和节肢动物群落内多物种相互作用的机制。这项研究是必要的和及时的，因为越来越多的生物控制剂可用于农业。此外，气候变化可能损害生物控制。 气温上升和极端气候事件增加不仅影响物种的表现，而且影响物种之间的相互作用。预计气候变化将通过改变（i）相对代谢率和相关过程（例如，发育，觅食，繁殖）之间的害虫和天敌，和（ii）空间和时间同步的生物控制剂和害虫。使用不同的捕食者-寄生物模型，以及我和我的学生最近收集的关于生物控制剂的热响应的大量数据集，我们建议研究（i）温度介导的代谢变化，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控制-通过使用一种指数，确定易受气候变化破坏的猎物/宿主-捕食者/寄生虫关系。 我的计划的第二个轴心涉及寄生黄蜂进化出的利用宿主的策略，更具体地说，是它们操纵宿主行为的能力。我希望研究，从近端和最终的机制，生态后果，一种类型的主机操纵，已在很大程度上未被探索：保镖操纵。我们观察到，寄生蜂有能力将其瓢虫宿主转化为保镖，同时在其茧内发育，这导致对发育中的寄生虫的捕食显著减少。此外，出乎意料的是，瓢虫可以从寄生中恢复。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特异性，季节生态学和农业生态系统中作用的理解。 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瓢虫的表现？其次，从应用的角度来看，寄生瓢虫有本质上相同的能力，以调节蚜虫种群作为unparasitized同种在田间条件下？

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?