How do female insects get switched on to reproduction?

雌性昆虫如何开始繁殖？

• 批准号: NE/X012387/1
• 负责人: Stuart Wigby
• 金额: $ 10.18万
• 依托单位: University of Liverpool
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FX012387%2F1
• 关键词: How; do; female; insects; get

Insects are highly adept at reproducing. The females of many insects lay huge numbers of eggs meaning that populations can increase very rapidly. This helps explain how insects have become the group of animals containing the most species, and also why some insects are so problematic for humans. Pest species that eat crops or carry human diseases can be extremely hard to control thanks to their phenomenal reproductive ability.But female insects don't typically lay eggs all the time. To avoid laying unfertilized eggs, females switch to high egg laying only after they've mated and received sufficient sperm from males. Alongside switching on egg laying, many female insects also avoid mating with males again until they need to obtain more sperm, in order to focus their energy on feeding and producing offspring.The molecules that cause these switches in behaviour in females are of great interest because they are key to insect reproductive success. If we know what the responsible molecules are we might be able to develop new pesticides that disrupt them, and control pest species in a very targeted way. Such knowledge is also important for our basic understanding of how evolution works, because we expect that genes that code for molecules that increase reproduction will typically become more common over successive generations.There are currently very few species for which we know the genes and molecules involved in switching on reproduction in females. The fruit fly, Drosophila melanogaster, is the best understood. Males in this species make a protein called 'Sex Peptide' (SP) which they transfer to females in the seminal fluid. After mating, SP activates a protein in the females called the 'Sex Peptide Receptor' (SPR) and this causes females to boost egg laying and reject further mating attempts from males. However, we don't know if SP and SPR do the same thing in other insect species. This is a big problem because it means we don't know whether SP and SPR switch on reproduction for lots of insect species, or whether different genes and molecules have evolved for this purpose elsewhere. If we knew the answer it would help us understand how insects evolve to reproduce so efficiently, and how we might control this in pest species using novel chemicals or improved biological control methods.We will address this problem by testing how SP and SPR work in a different insect species, Drosophila subobscura. This species is also a fly, it also has SP and SPR, but it is quite distantly evolutionarily related to Drosophila melanogaster. Drosophila subobscura females also show a very strong behavioural switch after mating: they boost egg laying and never mate again (because one mating provides all the sperm they ever need). This makes Drosophila subobscura species useful candidate for testing whether SP and SPR serve the same purpose over a fairly broad range of species.We will create genetically modified Drosophila subobscura that lack SP and SPR. We will then test them to see whether removing these molecules abolishes the normal boost to egg laying and rejection of males. The results will unequivocally answer the question of whether SP and SPR control the reproductive switch in Drosophila subobscura in the same way they do in Drosophila melanogaster, hence telling us how commonly these molecules play the same role. These results will thus create a step-change in our understanding of evolution of insect reproduction, and will pave the way for further studies across more species (including pest species), and for exploring other important reproductive molecules. The genetically modified flies we will generate will become an invaluable tool for our own future studies, and for other researchers with whom will share the flies freely.

昆虫非常善于繁殖。许多昆虫的雌性会产下大量的卵，这意味着种群数量可以迅速增加。这有助于解释昆虫如何成为包含最多物种的动物群体，以及为什么有些昆虫对人类来说如此成问题。吃庄稼或携带人类疾病的有害物种由于其惊人的繁殖能力而极难控制。但雌性昆虫通常不会一直产卵。为了避免产下未受精卵，雌性只有在交配并从雄性那里获得足够的精子后才会切换到高产卵量。除了开始产卵之外，许多雌性昆虫还会避免与雄性交配，直到它们需要获得更多的精子，以便将精力集中在喂养和繁殖后代上。引起雌性昆虫这些行为转变的分子引起了极大的兴趣，因为它们是昆虫繁殖成功的关键。如果我们知道哪些分子起作用，我们就可以开发出新的杀虫剂来破坏它们，并以一种非常有针对性的方式控制害虫物种。这些知识对于我们理解进化的基本原理也很重要，因为我们预计那些编码增加繁殖的分子的基因在连续的几代人中通常会变得更加普遍。目前，我们所知道的与雌性繁殖有关的基因和分子非常少。果蝇（Drosophila melanogaster）是人们了解得最多的。这个物种的雄性会制造一种叫做“性肽”（SP）的蛋白质，并通过精液传递给雌性。交配后，SP激活了雌性体内一种叫做“性肽受体”（SPR）的蛋白质，这使得雌性增加产卵量，并拒绝雄性的进一步交配尝试。然而，我们不知道SP和SPR是否在其他昆虫物种中起同样的作用。这是一个大问题，因为这意味着我们不知道SP和SPR是否开启了许多昆虫物种的繁殖，或者是否在其他地方进化出了不同的基因和分子来达到这个目的。如果我们知道答案，它将帮助我们理解昆虫是如何进化到如此高效地繁殖的，以及我们如何使用新的化学物质或改进的生物控制方法来控制害虫物种。我们将通过测试SP和SPR如何在另一种昆虫——果蝇亚bobscura中起作用来解决这个问题。这个物种也是一种苍蝇，它也有SP和SPR，但它与黑腹果蝇的进化关系很远。雌性亚bobscura果蝇在交配后也表现出非常强烈的行为转变：它们增加产卵量，不再交配（因为一次交配就能提供它们所需的所有精子）。这使得果蝇亚bobscura物种成为测试SP和SPR是否在相当广泛的物种中具有相同目的的有用候选者。我们将创造缺乏SP和SPR的转基因果蝇亚bobscura。然后，我们将对它们进行测试，看看去除这些分子是否会消除正常的促进产卵和雄性排斥的作用。该结果将明确回答SP和SPR是否以与黑腹果蝇相同的方式控制亚bobscura果蝇的生殖开关的问题，从而告诉我们这些分子发挥相同作用的普遍程度。因此，这些结果将为我们对昆虫繁殖进化的理解创造一个台阶，并为进一步研究更多物种（包括害虫物种）和探索其他重要的生殖分子铺平道路。我们将产生的转基因果蝇将成为我们自己未来研究的宝贵工具，也将成为其他研究人员自由分享果蝇的宝贵工具。