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Analysis of acquirement mechanism for nutritional resource in host-parasitoid interaction

寄主与寄生生物互作中营养资源获取机制分析

基本信息

批准号：
15380041
负责人：
TANAKA Toshiharu
金额：
$ 9.66万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

The nutritional relationship that is established between hosts and their parasites is never simple and often reflects a long co-evolutionary ‘arms-race' between each other. In this arms-race, hosts evolve mechanisms that enable them to escape from their parasites or to eliminate them ; on the other hand, the parasites need to overcome host defenses and utilize the host as a nutritional reservoir. The parasitoid larvae feed selectively on certain host tissues in order to keep a minimal damage to the host. Severe damage of the host during early development may lead to precocious death of the parasitoid. Feeding exclusively on the nutrient-rich hemolymph is one strategy that parasitoid. larvae employed to minimize host damage. Hemolymph retains a high nutritional value since it efficiently retrieves nutrients, which have already been or are to be stored in organs like the fat body via a specialized metabolic pathway, through inhibition of absorption of nutrients by the fat body, or only by slowly reducing the amount of fat body. The koinobiont larvae, however, possess well-developed gut to digest some foods during their late stages. Also, during late larval stages, the parasitoid larvae exhibit rapid growth just prior to pupation. These facts are difficult to explain on the sole basis of nutrient uptake from host hemolymph. Elucidation of how ecto- and endo-parasitic koinobionts utilize the hosts as a food resource will be useful in clarifying the evolution of common or different strategies in koinobionts. We studied strategies that enable parasitoids to ensure a sufficient food resource in both ecto- and endoparasitic koinobionts and explain how the parasitoid larvae utilize the host resource to enhance successful parasitism.

宿主和寄生虫之间建立的营养关系从来都不简单，往往反映了彼此之间长期的共同进化“军备竞赛”。在这场军备竞赛中，宿主进化出一种机制，使它们能够逃离寄生虫或消灭它们;另一方面，寄生虫需要克服宿主的防御，并利用宿主作为营养库。寄生蜂幼虫选择性地取食某些寄主组织，以保持对寄主的最小伤害。在发育早期，寄主的严重伤害可能导致寄生蜂的早熟死亡。专食营养丰富的血淋巴是拟寄生蜂的一种取食策略。幼虫用来减少宿主的损害。血淋巴保持高营养价值，因为它通过抑制脂肪体对营养的吸收或仅通过缓慢减少脂肪体的量，有效地回收已经或将要通过专门的代谢途径储存在脂肪体等器官中的营养。然而，koinobiont幼虫具有发育良好的肠道，可以在后期消化一些食物。此外，在后期幼虫阶段，寄生幼虫表现出快速增长之前化蛹。这些事实是难以解释的唯一基础上营养吸收宿主血淋巴。阐明外寄生和内寄生koinobions如何利用宿主作为食物资源将有助于澄清koinobions的共同或不同的策略的演变。我们研究的策略，使寄生虫，以确保足够的食物资源，在两个外寄生和内寄生koinobions和解释如何寄生幼虫利用宿主资源，以提高成功的寄生。