The reproductive and mating strategies of the twisted-winged parasites (Insecta: Strepsiptera): novel insights in the reproductive biology of an enigmatic insect order

在交配过程中，雄性和雌性之间的互动很少能达到完美的和谐，性侵犯在动物王国中很普遍。一种特别不寻常和奇怪的性侵犯形式是创伤性交配，在此期间，性伴侣的生殖器或其他身体部位受伤。创伤性交配是一种普遍存在的多方面现象，它在各种进化谱系中进化（例如，两栖动物、蜗牛、环节动物、线虫和节肢动物）。创伤性交配可以以不同的方式表现出来，例如创伤性插入（女性受伤）或创伤性授精（皮下注射精子）。创伤性授精发生在几种昆虫谱系中，特别是在臭虫和扭曲翅膀的寄生虫（Strepsiptera）中，这些寄生虫是表现出这种特殊交配模式的主要昆虫群体的教科书示例。然而，创伤性授精是否真的代表了Strepsiptera的一般交配策略还不清楚。事实上，最近有人假设，在Strepsiptera创伤性授精仅限于物种贫乏的Mengenillidae家族的物种，其雌性是自由生活的。那些雌性为永久性体内寄生虫（Stylopidia）的链翅目动物被认为已经切换回非创伤性交配。最后，有人认为Strepsiptera雌性只与一个雄性交配（单雄制），并且在群体中的性别之间没有共同进化的军备竞赛。我们的研究项目旨在研究鲜为人知的生殖生物学的神秘扭曲的翅膀寄生虫第一次全面和前所未有的细节。我们将采用跨学科的方法，包括各种学科的现代研究方法（即，比较解剖学和功能形态学、分子生物学、生物力学）。需要进行这项研究，因为上述关于链翅目生殖生物学的陈述在很大程度上是推测性的，可能为时过早。例如，我们有理由假定，创伤性授精发生在Strepsiptera的所有谱系中，而不仅仅是在Mengenillidae中，因此，这种昆虫目理应在教科书中被提及，作为普遍使用这种交配方式的主要生物群的例子。我们进一步假设，Strepsiptera女性的不同亚群可以得到多个男性受精（一妻多夫制），女性的形态适应创伤授精通过进化的耐受性性状。因此，我们的研究项目的结果不仅将揭示对Strepsiptera物种难以捉摸的生殖生物学的新见解，而且也将对研究性冲突和共同进化的进化生物学家产生重大兴趣。

The interaction between males and females during copulation rarely proceeds in perfect harmony, and sexual aggression is widespread in the animal kingdom. A particularly unusual and bizarre form of sexual aggression is traumatic mating, during which the genitals or other body parts of a sexual partner are injured. Traumatic mating is widespread and a multifaceted phenomenon and it evolved in various evolutionary lineages (e.g., amphibians, snails, annelids, nematodes, and arthropods). Traumatic mating can manifest itself in different ways, such as traumatic penetration (injury of the female) or traumatic insemination (hypodermal injection of sperm). Traumatic insemination occurs in several insect lineages, in particular in bed bugs and the twisted-winged parasites (Strepsiptera), which serve as text book examples for major insect groups exhibiting this peculiar copulation mode. Whether traumatic insemination indeed represents the general mating strategy of Strepsiptera is unclear, however. In fact, it has recently been postulated that in Strepsiptera traumatic insemination is limited to species of the species-poor family Mengenillidae, whose females are free-living. Those strepsipterans whose females are permanent endoparasites (Stylopidia) are assumed to have switched back to non-traumatic mating. Finally, it has been argued that Strepsiptera females mate only with a single male (monandry) and that there is no co-evolutionary arms race between the sexes in the group. Our research project aims to study the poorly known reproductive biology of the enigmatic twisted-winged parasites for the first time comprehensively and in unprecedented detail. We will apply an interdisciplinary approach that comprises a wide array of modern research methods from various disciplines (i.e., comparative anatomy and functional morphology, molecular biology, biomechanics). This study is required as the above statements on the reproductive biology of Strepsiptera are largely speculative and likely premature. For example, we have reason to assume that traumatic insemination occurs in all lineages of Strepsiptera, not only in Mengenillidae, and that this insect order thus legitimately deserves to be mentioned in text books as example for a major group of organisms that makes general use of this mode of copulation. We furthermore assume that Strepsiptera females of different subgroups can get fertilized by multiple males (polyandry), and that females are morphological adapted to traumatic insemination via evolution of tolerance traits. The results of our research project will thus not only reveal novel insights into the elusive reproductive biology of species of Strepsiptera, but will also be of major interest to evolutionary biologists who study sexual conflict and co-evolution.