The role of cuticular hydrocarbons in adaptations to changing climatic conditions and in sexual communication of Anopheles mosquitoes

疟疾是一种媒介传播的疾病，目前威胁着世界上一半的人口。按蚊传播疟疾，已经开发了许多工具来防止蚊子叮咬，如驱蚊剂和经杀虫剂处理的蚊帐。尽管自千年以来疟疾大幅减少，但目前的控制方法停滞不前，部分原因是疟疾蚊媒出现了杀虫剂抗药性。此外，蚊子入侵了世界上的新地区，从而增加了人们感染疟疾的风险。更好地了解蚊子的生物学和生态学可能会导致蚊子媒介控制的新方法的发展。在这里，我们将集中在两种按蚊/物种复合体上，并将研究在它们身上发现的一类化合物如何帮助蚊子识别交配伙伴和在新的区域定居。这些化合物是角质层碳氢化合物，它们在蚊子的角质层上形成一层蜡状层--它们是皮肤的类似物。在其他昆虫中，角质层碳氢化合物已知有两个作用。它们防止水分流失-干燥，这很可能发生在蚊子生活的炎热热带环境中。它们也被用作一种有吸引力的香水，用来识别合适的交配伙伴。然而，表皮层碳氢化合物在疟疾蚊子中的作用还不是很清楚，这个项目开始测试它。我们将重点研究我们选择的两种按蚊，因为它们具有特殊的兴趣。第一种是斯氏按蚊，原产于印度，但在过去10年里入侵了非洲之角。在从印度迁徙后，这些蚊子必须适应阿拉伯半岛和东非的干燥和炎热的气候并在其中生存。因此，对不同环境条件的任何适应也必须是非常近期的，而且正在非常迅速地发生。我们现在有机会研究这一独特的生物过程，因为它发生了，我们预测，角质层碳氢化合物的变化有助于这些蚊子入侵非洲。此外，斯氏按蚊还必须将它们潜在的交配伙伴与非洲本土按蚊物种区分开来。这意味着他们迷人的香水，如果他们使用的话，可能已经被修改--这再次让我们研究角质层碳氢化合物。第二个感兴趣的物种是法拉乌蒂按蚊，生活在澳大利亚北部、巴布亚新几内亚、所罗门群岛和瓦努阿图。事实上，这不是一个物种，而是一个由8个密切相关的物种组成的复合体，其中一些物种出现在同一地点，一些物种生活在与亲戚隔绝的岛屿上。到目前为止，我们已经研究了生活在澳大利亚北部的8种物种中的1种。我们发现该物种雄性和雌性的角质层碳氢化合物有很大的不同。这一令人兴奋的发现表明，它们确实可能使用表皮层碳氢化合物作为香水来选择配偶，就像在许多其他昆虫物种中所显示的那样。我们现在想把我们的研究扩展到其他兄弟物种，看看它们的角质层碳氢化合物是否在雄性和雌性之间有所不同。我们预测它们是相同的，但当蚊子的亲戚住在同一地点时，它们会略有修改。法拉乌蒂按蚊和/或斯氏按蚊使用化合物寻找配偶，这一发现将对其他蚊子物种和蚊子控制策略产生深远影响。然后，负责产生和感知表皮层碳氢化合物的蚊子基因和蛋白质可能会以各种方式作为靶标，导致我们迫切需要的疟疾媒介控制的新方法。此外，如果我们发现快速变化的表皮层碳氢化合物有助于蚊子适应不断变化的气候的证据，这将有助于科学家预测蚊子种群未来可能如何在世界各地迁徙和入侵。这可能会指导将拯救数百万人生命的预防战略。

Malaria is a vector-borne disease that currently threatens half of the world population. Anopheles mosquitoes transmit malaria, and many tools have been developed to prevent mosquito bites, such as mosquito repellents and insecticide-treated bed nets. Despite the huge reductions in malaria since the millennium, present control methods have stalled, partly due to emerging insecticide resistance in malaria mosquito vectors. In addition, mosquitoes invade new regions of the world, thus increasing the risk of malaria to people. Better understanding of mosquito biology and ecology could lead to the development of novel methods of mosquito vector control.Here we will focus on two species/species complexes of Anopheles mosquitoes, and will study how a class of chemical compounds that is found on their bodies helps mosquitoes to recognize mating partners and to colonize new areas. These compounds are cuticular hydrocarbons, and they form a waxy layer on the mosquito cuticle - their analogue of skin. In other insects, cuticular hydrocarbons are known to have two roles. They prevent water loss - desiccation, which is likely to occur in hot tropical environments where mosquitoes live. They are also used as an attractive perfume for recognizing appropriate mating partners. However, the role of cuticular hydrocarbons in malaria mosquitoes is not well known, and this project sets out to test it.We will focus on the two Anopheles species that we selected because of the special interest that they present.The first species, Anopheles stephensi, are native to India, but have in the past 10 years invaded the Horn of Africa. Upon migration from India, these mosquitoes had to adapt to and survive in dry and hot climate of the Arabian peninsula and East Africa. Thus, any adaptations to different environmental conditions must also be extremely recent and are happening very rapidly. We have a chance now to study this unique biological process as it occurs, and we predict that changes in cuticular hydrocarbons help these mosquitoes in their invasion of Africa. In addition, An.stephensi also have to distinguish their potential mating partners from the native African Anopheles species. This means that their attractive perfumes, if they use them at all, might have been modified - this again brings us to study cuticular hydrocarbons. The second species of interest, Anopheles farauti, inhabits northern Australia, Papua New Guinea, the Solomon islands and Vanuatu. In fact, this is not one species but a complex of 8 closely related species, some of which occur at the same locations, and some live on islands in isolation from their relatives. We so far have studied 1 of the 8 species that inhabits Northern Australia. We found that cuticular hydrocarbons of the males and females of this species are very different. This exciting finding implies that they may indeed use cuticular hydrocarbons as the perfume to select their mates as it has been shown in many other insect species. We now want to extend our study to the other sibling species, and see whether their cuticular hydrocarbons are different between males and females. We predict that they are, but are modified slightly when the relatives of the mosquitoes live at the same location. The finding that An.farauti and/or An.stephensi use chemical compounds to find their mates will have profound implications for other mosquito species and mosquito control strategies. Mosquito genes and proteins, responsible for production and perception of cuticular hydrocarbons, may then be targeted in a variety of ways, leading to novel methods of malaria vector control that we urgently need. In addition, if we find evidence that rapidly changing cuticular hydrocarbons helps mosquitoes adapt to changing climate, this will help the scientists predict how mosquito populations may migrate and invade around the world in the future. This may guide prevention strategies that will save millions of human lives.