Resource dependence of chemical defense and life-history patterns in oribatid mites

生物体与环境中的其他生物进行敌对的相互作用，并拥有防御策略，以保护自己免受捕食者、寄生虫或竞争对手的攻击。特别是在陆地节肢动物中，化学防御性分泌物对捕食者-猎物相互作用的动力学至关重要。甲螨是除北极地区外的世界各地生态系统中种类最多、种类最多、数量最多的藻类，分布在森林土壤和凋落物、地衣、苔藓和树皮上。已经描述了大约10,000个物种，温带森林土壤生态系统的丰富度达到每平方米数十万个个体。大多数甲螨种类(腺体)具有一对外分泌后体腺，产生碳氢化合物、萜类和芳香烃的复杂混合物(有些种类还产生生物碱)；这些腺体储存在水库中，以备即刻使用。甲壳虫油腺分泌物的生物学功能的解释长期以来一直是相当猜测的，但我们最近提供了第一个实验证据，证明它们作为异构体具有适应价值。基于防御分泌物和捕食者攻击频率的定量再生数据，我们进一步发展了一个被称为“可还原防御”的功能反应模型，表明基于水库的化学防御是一个高度动态的过程。在这里，防御性分泌物的生物合成再生率塑造了捕食者-猎物相互作用的动态，并对相互作用的稳定性或不稳定性负责，因此，对于包括水库为基础的化学防御的猎物物种的整个土壤食物网而言。防御性分泌物的再生具有很高的能量成本，这当然也会影响其他生活史参数(生长、繁殖、发育)。然而，资源质量与更新/生活史的关系仍有待阐明。因此，我们想在依赖资源的化学防御和生命史参数的背景下解决四个科学问题。问题1：营养成分如何影响油腺化学成分(质量和数量)和生活史参数(如生长、繁殖)的功能表现？问题2：哪些营养物质是油腺分泌生物合成所必需的？问题3：油腺化合物的不同化学类别(特别是芳香族)是如何合成的？问题4：甲螨在选择资源时是否执行最佳觅食，以及这种选择基于哪些感官机制？

Organisms interact antagonistically with others in their environment and possess defensive strategies for protection against predators, parasites or competitors. Especially among terrestrial arthropods, chemical defensive secretions are of outmost importance for the dynamics of predator prey interactions. Oribatid mites are among the most speciose chelicerate groups, and most diverse and abundant in forest soil and litter, on lichens, mosses and bark in ecosystems all over the world, except the arctic region. About 10,000 species have been described, and abundances in temperate forest soil ecosystems reach hundreds of thousands of individuals per square meter. Most oribatid mite species (glandulate Oribatida) possess a pair of exocrine opisthosomal glands, producing complex blends of hydrocarbons, terpenes and aromatics (some species also produce alkaloids); these are stored in reservoirs for immediate availability. The interpretation of the biological function of oribatid oil gland secretions was quite speculative for a long time, but we have recently provided the first experimental evidence for their adaptive value as allomones. Based on quantitative regeneration data of defensive secretions and predator attack frequencies, we further developed a functional response model called "reducible defence", demonstrating that reservoir based chemical defence is a highly dynamic process. Here, the biosynthetic regeneration rate of defensive secretions shapes the dynamics of predator prey interactions and is responsible for stability or instability of the interaction and, in consequence, for the whole part of soil food webs that include reservoir based chemically defended prey species. The regeneration of defensive secretions has a high energetic cost which certainly also influences other life history parameters (growth, reproduction, development). However, the relation of resource quality and regeneration / life history remains to be elucidated. Hence, we want to address four scientific questions in the context of resource dependent chemical defense and life history parameters. Q1: How does nutritional composition affect the functional performance of oil gland chemistry (quality and quantity) and life history parameters (e.g. growth, reproduction)?Q2: Which nutrients are essential for oil gland secretion biosynthesis?Q3: How are the different chemical classes (especially aromatics) of oil gland compounds synthesized?Q4: Do oribatid mites execute optimal foraging when choosing resources and on which sensory mechanisms is this choice based on?