Investigating symbiont impacts on natural enemy susceptibility in ladybird beetles.

背景：许多昆虫携带可遗传的共生体，即从亲代传给后代的细菌，这些细菌在瓢虫中尤为常见。过去关于瓢虫共生体的研究强调了生殖寄生虫的表型，如雄性杀死，但它们也可能是防御天敌攻击的重要组成部分（保护性共生）。在这里，共生体将代表个体抗性和宿主-寄生虫相互作用动力学的重要决定因素。反过来说，共生动态部分是由寄生虫驱动的。线虫对寄主生育力的影响也使这成为使用瓢虫作为绿蝇防治措施的重要考虑因素。目的1。我们将研究寄主范围、多样性、环境和景观与瓢虫寄生的关系。这将涉及实地取样、公民科学和开发分子生态学方法的结合，以检测它们的存在和多样性。目的2：我们将进行实验，分析螺原体细菌是否在不同种类的瓢虫中提供防御线虫的攻击。目标3：我们将确定共生体的存在和攻击强度是否在物种内部和物种之间相互关联。新颖性：我们将应用最先进的下一代测序方法，通过公民科学收集和记录计划来调查线虫的多样性，以建立英国瓢虫物种中线虫的存在。与共生体的界面是一项新的研究，而瓢虫是天敌攻击的模型系统，而共生体对天敌攻击的影响尚未确定。及时性：尽管早在50多年前就被发现了，但瓢虫中线虫攻击的多样性和强度尚不清楚，除了入侵物种黑毛瓢虫，其攻击率最近被证明很高。最近对果蝇的研究表明，在瓢虫中也发现了螺原体共生体，作为一种主要的防御手段。

Background: Many insects carry heritable symbionts, bacteria that pass from parent to offspring, and these are particularly common in ladybird beetles. Past work on ladybird symbionts has emphasised reproductive parasite phenotypes such as male-killing, but it is likely that they are also an important component of defence against natural enemy attack (protective symbiosis). Here, symbionts would represent an important determinant of individual resistance and in the dynamics of the host-parasite interaction. Reciprocally, the symbiont dynamics would be driven partly by the parasite. The impact of nematodes on host fertility additionally make this an important consideration in use of ladybirds as greenfly control measures.Objective 1. We will examine the host range, diversity, environmental and landscape correlates of parasitisation of ladybirds with tylnechid nematodes. This will involve a combination of field sampling, citizen science and development of molecular ecology methods for detecting their presence and diversity.Objective 2: We will perform experiments to analyse if Spiroplasma bacteria provide defence against nematode attack in different species of ladybird.Objective 3: We will determine if presence of symbionts and intensity of attack are correlated both within species over space, and between species.Novelty: We will apply state of the art next generation sequencing methods to investigate nematode diversity with a citizen science collection and recording programme to establish nematode presence across UK ladybird species. The interface with symbionts represents novel research whilst ladybirds are a model system for natural enemy attack and for symbionts, the impact of symbionts on enemy attack has not been ascertained.Timeliness: Despite being discovered over fifty years ago, the diversity and intensity of nematode attack in ladybirds is unknown, save in the invasive species Harmonia axyridis, where attack rates have recently been shown to be high. Very recent work in Drosophila has demonstrated Spiroplasma symbionts also found in ladybirds as a principle means of defence.