COLONISATION, DOMESTICATION AND POPULATION CONTROL IN PEST INSECTS

保障世界粮食供应是一个巨大的挑战。因此，开发安全、环保、有效的农业重要作物害虫防治新技术具有重要意义。一种非常重要的现有方法是昆虫不育技术（SIT），其中昆虫被大量饲养，通过辐射灭菌并大量释放。不育的释放雄性与野生雌性交配，因为这些交配不产生后代，害虫种群的规模减少。SIT的应用取得了一些巨大的成功，但也有明显的失败。为了避免已知的问题（例如，通过辐射对男性进行绝育而导致的健康损失），人们对基因改造（GM）技术的应用越来越感兴趣。其中之一是由项目合作伙伴（Oxitec）发明的释放显性致死昆虫（RIDL）。在这种情况下，雄性可以在不绝育的情况下被释放，并且释放的个体很容易通过荧光标记在野外跟踪。RIDL之所以有效，是因为被释放的雄性携带了一种转基因，导致继承它的女儿在发育过程中死亡，这种影响可以持续几代人。致命性主要集中在雌性身上，因为它们产卵时会破坏庄稼和水果。然而，一个潜在的重大障碍仍然存在。为了释放大量害虫，在实验室设施中驯化并大量饲养害虫。这不可避免地选择了在实验室中非常成功的个体，而不是在野外（释放的雄性必须找到野生雌性并与之交配，才能使这项技术发挥作用）。毫不奇怪，有几个例子，现场表现不佳的SIT男性和/或野生女性宁愿不与them.Despite这些缺点的广泛知识，一直没有研究适应实验室条件的害虫用于SIT为基础的方法在真实的时间，以了解，从而尽量减少，不必要的变化，在关键的生活史特征。此外，越来越清楚的是，对健康的重大贡献来自与肠道细菌的关联。在昆虫中，肠道细菌具有广泛和令人惊讶的影响，例如它们可以改变宿主的寿命，配偶选择，生殖生理学，发育和代谢。这种影响通常也取决于饮食，当昆虫被带到实验室并吃较少种类的食物时，肠道细菌的多样性就会减少。然而，也没有系统的研究肠道细菌在驯化过程中的变化，因此对宿主的连锁反应，例如对它们抑制害虫种群规模的能力。因此，肠道细菌的变化是实验室适应的重要组成部分。它们在RIDL的背景下特别令人感兴趣，其中通过使用膳食抗生素来控制雌性致死率的表达。作为副作用，这也会改变肠道微生物的影响和多样性，因此我们需要了解宿主及其肠道细菌如何适应实验室大量饲养条件。有了这些知识，这种适应的不良影响可以减缓或逆转。因此，主要目的是使用地中海实蝇（一种具有世界重要性的农业害虫）记录生活史、肠道细菌及其相互作用的变化，这些变化发生在实验室定植后，并能够实现种群抑制。具体目标是：1.在不同的食物制度下，测试30代殖民到实验室的野生个体的表现。测试1.3以下个体肠道细菌的相关变化。测试操纵肠道细菌对维持在稳定或可变饮食方案下的个体的影响的差异。评估益生菌恢复定植过程中细菌丢失的可行性。

Safeguarding world food supplies is a grand challenge. It is therefore of great importance to develop safe, environmentally friendly and effective new techniques for tackling pests of agriculturally important crops. An existing method that has been very important is the sterile insect technique (SIT), in which insects are mass reared, sterilised by irradiation and released in large numbers. Sterile released males mate with wild females, and because these matings produce no offspring, the size of the pest population is reduced. SIT has been applied with some great successes - but also notable failures. To circumvent known problems (for example, the loss in health that results from sterilizing males with irradiation) there is increasing interest in the application of Genetic Modification (GM) technologies. One of these is known as the Release of Insects with a Dominant Lethal (RIDL), invented by the Project Partner (Oxitec). In this, males can be released without sterilization, and the released individuals are easy to track in the field via fluorescent markers. RIDL works because the released males carry a transgene that causes daughters that inherit it to die during development, an effect that can persist for several generations. The lethality is focused on females because they spoil crops and fruits when laying eggs. However, one potentially significant hurdle remains. To release large numbers, pest insects are domesticated and mass reared in laboratory facilities. This inevitably selects for individuals that are highly successful in the laboratory, rather than in the field (the released males must locate and mate with wild females for the technique to work). Unsurprisingly, there are several examples of poor field performance of SIT males and/or wild females preferring not to mate with them.Despite widespread knowledge of these drawbacks, there has been no study of adaptation to laboratory conditions for pest insects used for SIT-based approaches in real time, in order to understand, and hence minimize, unwanted changes in key life history traits. In addition, it is increasingly clear that a significant contribution to health comes from associations with gut bacteria. In insects, gut bacteria have widespread and surprising effects, e.g. they can alter host lifespan, mate choice, reproductive physiology, development and metabolism. Such effects also often depend upon diet, and the diversity of gut bacteria is diminished when insects are brought into the laboratory and eat less varied foods. However, there has also been no systematic study of changes in gut bacteria during domestication and hence the knock-on effects on hosts, e.g. on their ability to suppress pest population size. Changes to gut bacteria are therefore an important component of laboratory adaptation. They are of particular interest in the context of RIDL, in which the expression of female lethality is controlled by use of a dietary antibiotic. This will - as a side effect - also alter the effects and diversity of gut microbes.We therefore need to understand how hosts and their gut bacteria adapt to laboratory mass rearing conditions. With this knowledge, undesirable effects of such adaptation can be slowed or reversed. The main objective is therefore to use the medfly (an agricultural pest of world-wide importance) to document changes in life history, gut bacteria, and their interaction, upon colonization to the laboratory and the ability to achieve population suppression. The specific aims are:1. Test the performance of wild individuals subject to 30 generations of colonization to the laboratory, under variable food regimes.2. Test associated changes in the gut bacteria of the individuals under 1.3. Test for differences in the effects of manipulating gut bacteria on individuals maintained under either stable or variable dietary regimes.4. To assess the feasibility of probiotics to restore bacteria lost during colonization.