Understanding density-dependent disease resistance in insects

了解昆虫的密度依赖性抗病性

• 批准号: NE/G009902/1
• 负责人: Kenneth Wilson
• 金额: $ 3.49万
• 依托单位: Lancaster University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FG009902%2F1
• 关键词: Understanding; density; dependent; disease; resistance

There are lots of benefits to living in groups, such as increased protection from predators and greater opportunities for finding food and mates. However, being part of a crowd also carries a number of costs. One of these is the risk of becoming infected by a parasite or pathogen from another member of the group. This is because most infections are transmitted between individuals in a density-dependent manner: the more individuals there are, the greater the probability of bumping into an infected individual. Recently, it has been discovered that many species appear to have evolved a strategy to cope with this density-related increase in the risk of becoming infected. This strategy is known as 'density-dependent prophylaxis' (DDP). A number of studies, mainly on insects, have shown that as the degree of crowding (and the risk of infection) increases, so individuals appear to invest more of their limited resources into disease resistance mechanisms, such as the immune system, and as a result they are much more resistant to parasites. For example, our previous work on African armyworms has shown that caterpillars that grow up in a crowded environment have significantly better immunity and are up to 10 times more resistant to viruses than are their siblings that grow up in isolation. This DDP phenomenon is now well established in the scientific literature. However, we know very little about how the insects translate differences in population density (crowding) into differences in immunity and disease resisatnce. This is the focus of the proposed study. The purpose of this grant is to test the hypothesis that Juvenile Hormone (JH) plays an important role in this DDP phenomenon. Although we have a good understanding of the effects of hormones, such as corticosteroids, on the vertebrate immune system, very little is known about the hormonal control of immunity and disease resistance in insects. In fact, the main text book on insect hormones (published in 1994) includes no mention of the effects of insect hormones on disease resistance. However, a number of more recent studies suggest that JH may be involved. We plan to test the idea that juvenile hormone is responsible for increasing disease resistance under crowded conditions using caterpillars of the African armyworm. Just like the desert locust, this species occurs in two alternate forms depending on the level of crowding it experiences - one adapted to low-density conditions and one adapted to crowded conditions. It also shows crowding-related variation in immunity (see above). We will manipulate JH levels in these caterpillars, up and down, in order to determine whether this leads to a change in immunity and disease resistance. If we understand the role of hormones correctly, then we predict that by increasing JH levels we will stimulate some aspects of insect immunity and disease resistance (i.e. DDP). By the end of the grant, we should have a better understanding of the role of juvenile hormone in regulating how insects adapt to changes in their environment (i.e. the degree of crowding), as well as the role of JH in mediating key aspects of immunity and disease resistance in insects. Longer-term, we hope to gain a more complete understanding of the role of the insect hormonal system in generating variation in immunity and resistance to a wide range of parasites and pathogens.

群居生活有很多好处，比如增加对捕食者的保护，增加寻找食物和配偶的机会。然而，成为人群的一部分也需要付出一些代价。其中之一是被来自该群体另一成员的寄生虫或病原体感染的风险。这是因为大多数感染是以密度依赖的方式在个体之间传播的：个体越多，撞到感染个体的概率就越大。最近，人们发现许多物种似乎已经进化出一种策略来科普这种与密度相关的感染风险增加。这种策略被称为“密度依赖性预防”（DDP）。许多研究，主要是对昆虫的研究，表明随着拥挤程度（和感染风险）的增加，个体似乎将更多的有限资源投入到抗病机制中，如免疫系统，因此他们对寄生虫的抵抗力更强。例如，我们之前对非洲粘虫的研究表明，在拥挤环境中长大的毛虫具有更好的免疫力，对病毒的抵抗力比在隔离环境中长大的兄弟姐妹高出10倍。这种DDP现象现在在科学文献中得到了很好的证实。然而，我们对昆虫如何将种群密度（拥挤）的差异转化为免疫力和疾病抵抗力的差异知之甚少。这是拟议研究的重点。这项资助的目的是检验保幼激素（JH）在这种DDP现象中起重要作用的假设。虽然我们对激素（如皮质类固醇）对脊椎动物免疫系统的影响有很好的了解，但对昆虫免疫和抗病性的激素控制知之甚少。事实上，关于昆虫激素的主要教科书（1994年出版）没有提到昆虫激素对抗病性的影响。然而，最近的一些研究表明，JH可能参与其中。我们计划用非洲粘虫的毛虫来验证保幼激素是在拥挤的条件下增加抗病能力的原因的想法。就像沙漠蝗虫一样，该物种根据其所经历的拥挤程度以两种交替形式出现-一种适应低密度条件，另一种适应拥挤条件。它还显示了免疫力的拥挤相关变化（见上文）。我们将操纵这些毛虫中的JH水平，上下，以确定这是否会导致免疫力和抗病力的变化。如果我们正确理解激素的作用，那么我们预测，通过增加JH水平，我们将刺激昆虫免疫和抗病性（即DDP）的某些方面。到拨款结束时，我们应该更好地了解保幼激素在调节昆虫如何适应环境变化（即拥挤程度）中的作用，以及保幼激素在介导关键方面的作用。昆虫的免疫力和抗病力。从长远来看，我们希望能够更全面地了解昆虫激素系统在产生免疫力变化和对各种寄生虫和病原体的抵抗力方面的作用。

项目成果

Dynamics of macronutrient self-medication and illness-induced anorexia in virally infected insects.

• DOI: 10.1111/1365-2656.12127
• 发表时间: 2014-01
• 期刊: The Journal of animal ecology
• 作者: Povey S;Cotter SC;Simpson SJ;Wilson K
• 通讯作者: Wilson K

Transgenerational effects modulate density-dependent prophylactic resistance to viral infection in a lepidopteran pest.

跨代效应调节鳞翅目害虫对病毒感染的密度依赖性预防性抵抗力。

• DOI: 10.1098/rsbl.2015.0012
• 发表时间: 2015
• 期刊: Biology letters
• 影响因子: 3.3
• 作者: Wilson K