昆蟲病毒對寄主免疫與學習之調節

Abstract

膜翅目昆蟲在生物界中擁有許多重要地位，也是昆蟲綱 (Incecta) 中第三大目 (Order)，牠們不僅是重要的社會性昆蟲代表也是許多植物的受粉者。這類昆蟲居多皆有極佳的飛行能力，能探索長距離的巢外環境亦能有較廣的環境資源。然而，也因為牠們接觸的環境較為多元，其所面臨的環境壓力也可能因此增加。膜翅目昆蟲病毒的研究在近年受到高度重視，本論文即在探討小繭蜂與西方花蜜蜂之病毒研究。膜翅目昆蟲體內的病毒性病原菌未必皆會使其帶原寄主死亡，在馬尼拉小繭蜂體內有著一種特殊共生性病毒，其名為多去氧核糖核酸病毒 (Polydnavirus, PDV)，此病毒會在雌性馬尼拉小繭蜂的卵巢中利用卵萼細胞進行大量的病毒複製，但不會對馬尼拉小繭蜂造成任何毒性傷害，反而會幫助馬尼拉小繭蜂在寄生鱗翅目寄主時壓制寄主的免疫系統，使其幼蟲能在鱗翅目寄主體內完好發育。另外在西方花蜜蜂的研究中，因近年各種環境因子、農藥施用、蟲生病原菌等逆境非生物及生物性壓力，造成蜜蜂巢內有大量工蜂因不知明原因而消失。而近期的研究指出，在蜜蜂越冬時，會嚴重感染蜜蜂的畸翅病毒 (Deformed wing virus, DWV) 即是使蜜蜂大量死亡的原因之一，也因為此病毒對蜜蜂全生活史皆可感染，故其所造成的生物性逆境壓力會從蜜蜂幼蟲持續累積到成蜂階段，使蜂巢整體健全程度影響甚鉅。故在本篇研究中，我們將探討不同膜翅目昆蟲體內的不同種病毒，如何影響其寄主的生理系統，研究此生物性逆境所造成的結果是幫助其寄主，亦或是使其寄主受毒力影響而出現不正常生理反應。此研究將有助於釐清昆蟲在病理學中，病原菌造成的生物性逆境下如何影響寄主和寄主生理系統的反應。

Hymenopterans are some of the most important creatures in the wild world. The third largest order within Insecta, they are the mainly social insects and major pollinators, contributing greatly to plant diversity. Due to their powerful flight ability, which enables them to search for diverse resources across significant distances, they encounter a greater variety of environmental stresses then other insects. In recent years, Hymenopteran viruses have been highlight in various scientific reports. In our studies, we focus on the two different pathogenic virus of Snellenius manilae and Apis mellifera. Polydnavirus (PDV), a symbiont of Braconidae parasitoids, replicate in their ovaries without causing any virulence to the parasitoid. In fact, Snellenius manilae braconirus (SmBV), a kind of PDV, actually helps Snellenius manilae protect its offspring from the immune response of the parasitized host. It not only shuts down their host’s immune system, but also changes their metabolism of the parasitized caterpillar larvae. On the other hands, populations of Apis mellifera, also known as the western honey bee, have been declining in recent years. Whilst the cause is still not fully understood, with some studies suggesting a combination of pesticide abuse, various environmental factors and pathogen, it could be linked to deformed-wing virus (DWV) which causes significant damage to a great many hives and honey bee each winter. It can infect all stages of honey bees, and results in adult bees growing a pair of “useless”. Severely infected bees are not expected to survive for more than 48 hours or be able to return back to the hive. With this in mind, our study focuses on the physiological effects from different types of infectious viruses in hymenopterans and different phenomena a arising from the biological stress. This will help further our understanding of relationship between insect physiology and pathology.