How tri-trophic interactions and social behaviour drive early instar survival rates of caterpillars

我的目标是为毛虫早期幼虫生态学建立一个基于过程的概念框架，通过确定物候、植物物理和化学防御、群体生活和天敌如何相互作用来产生幼虫生存的新模式。总体而言，对幼虫的研究很少，但由于相互作用的物种特有的应激因素，幼虫往往遭受非常不同的高死亡率。这种在空间和时间上的高度变异性表明，早期幼虫的存活在种群动态中扮演着重要的角色。*我的比较方法使用了三个系统，因为它们在生活史、聚集性和种群动态上的差异而被选择：加拿大两种重要的暴发森林害虫--云杉芽孢虫(Choristoneura fumiferana，独居，取食针叶树)，森林帐篷毛虫(Malacosoma disstria，群居，落叶食性)和多样化的热带空地蝴蝶(Ithominae，一些物种群居，另一些物种独居)。*1.是什么行为机制驱动了加拿大东部最重要的森林害虫早期幼龄存活率的波动？早期幼虫存活率的极端差异构成了预测芽孢杆菌暴发的一个重要知识缺口。我将通过测试将寄主植物物候、叶片化学和先前的落叶与扩散、竞争和建立取食地点联系起来的行为机制来填补这一空白。*2.群体生活如何调节森林帐篷毛虫中的三营养相互作用？我将测试一种假设，即群体生活意味着随着群体变小，存活率会下降，这种反馈会加速由于捕食和植物防御而造成的消耗。*3.群体生活如何调节毛虫的三营养相互作用？我将把使用温带群居毛虫开发的概念和工具应用于热带发现的更大的多样性；具体地说，我将测试分组如何允许在机械防御的植物上建立和定居受干扰的栖息地。*这些子目标利用每个研究有机体的特定自然历史来制定关于驱动早期幼虫生态的机制的假设。他们共同组成了一个雄心勃勃的、创新的、范围广泛的研究计划，综合了相互作用的压力源的影响，以解释早期幼虫生存过程中复杂的紧急模式。我独特的基于个人的方法为热带森林的保护提供了坚实的科学基础，并从机械上解释了北方森林的疫情动态，包括对气候变暖的反应。对暴发害虫的研究尤其及时，因为这两项研究目前正在加拿大大部分地区掀起高潮。**

My goal is to build a process-based conceptual framework for caterpillar early-instar ecology, by determining how phenology, plant physical and chemical defenses, group-living and natural enemies interact to produce emergent patterns of larval survivorship. In general, young larvae are poorly studied, but often suffer very variable high mortality rates caused by interacting species-specific stressors. This high variability in space and time implies that early-larval survival plays an important role in population dynamics. ******My comparative approach uses three systems chosen for their differences in life history, gregariousness and population dynamics: two important Canadian outbreaking forest pests - spruce budworm (Choristoneura fumiferana, solitary, conifer-feeders), forest tent caterpillars (Malacosoma disstria, gregarious, deciduous-feeders) and the diverse tropical clearwing butterflies (Ithominae, some species gregarious, others solitary). ***1. What behavioural mechanisms drive fluctuations in early-instar survival of Eastern Canada's most important forest pest? Extreme variations in early-instar survival constitute an important knowledge gap in predicting budworm outbreaks. I will fill this gap by testing behavioural mechanisms linking host plant phenology, leaf chemistry and previous defoliation to dispersal, competition and establishment of a feeding site. ***2. How does group-living modulate tri-trophic interactions in the forest tent caterpillar? I will test the hypothesis that group living implies a decrease in survival rate as groups get smaller, and that this feedback accelerates the attrition due to predation and plant defenses. ***3. How does group-living modulate tri-trophic interactions in clearwing caterpillars? I will apply the concepts and tools developed using temperate-zone gregarious caterpillars to the far greater diversity found in the tropics; specifically, I will test how grouping permits establishment on mechanically defended plants and colonization of disturbed habitats. ******These sub-objectives draw on the particular natural history of each study organism to formulate hypotheses about mechanisms driving early-instar ecology. Together they form an ambitious, innovative, wide-ranging research programme that synthesizes the effects of interacting stressors to explain complex emergent patterns in early-instar survivorship. My unique individual-based approach provides solid scientific grounding for conservation in tropical forests and mechanistic explanations of outbreak dynamics in the boreal forest, including responses to climate warming. The research on outbreaking pests is particularly timely since both are currently on the upsurge across much of Canada.**