Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan.
National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8566, Japan.
Zoolog Sci. 2020 Oct;37(5):399-410. doi: 10.2108/zs200054.
Cockroaches are commonly found in human residences and notorious as hygienic and nuisance pests. Notably, however, no more than 30 cockroach species are regarded as pests, while the majority of 4,500 cockroaches in the world are living in forest environments with little relevance to human life. Why some cockroaches have exceptionally adapted to anthropic environments and established pest status is of interest. Here we investigated the German cockroach , which is a cosmopolitan pest species, and the forest cockroach , which is a wild species closely related to . In contrast to easy rearing of , laboratory rearing of was challenging-several trials enabled us to keep the insects for up to three months. We particularly focused on the distribution patterns of specialized cells, bacteriocytes, for harboring endosymbiotic , which has been suggested to contribute to host's nitrogen metabolism and recycling, during the postembryonic development of the insects. The bacteriocytes were consistently localized to visceral fat bodies filling the abdominal body cavity, where a number of single bacteriocytes were scattered among the adipocytes, throughout the developmental stages in both females and males. The distribution patterns of the bacteriocytes were quite similar between and , and also among other diverse cockroach species, plausibly reflecting the highly conserved cockroach- symbiotic association over evolutionary time. Our study lays a foundation to experimentally investigate the origin and the processes of urban pest evolution, on account of possible involvement of microbial associates.
蟑螂通常存在于人类住所中，以卫生和滋扰害虫而闻名。然而，值得注意的是，只有不超过 30 种蟑螂被认为是害虫，而世界上 4500 种蟑螂中的大多数生活在与人类生活几乎没有关系的森林环境中。为什么有些蟑螂能够异常适应人为环境并确立害虫地位是一个有趣的问题。在这里，我们研究了德国蟑螂，它是一种世界性的害虫物种，以及与它密切相关的森林蟑螂。与容易饲养的相比，实验室饲养的则具有挑战性——经过几次尝试，我们才成功地将昆虫饲养了长达三个月。我们特别关注专门细胞——细菌细胞的分布模式，这些细胞用于容纳内共生菌，内共生菌被认为有助于宿主的氮代谢和回收，这在昆虫的胚胎后发育过程中尤为重要。细菌细胞始终位于填满腹部体腔的内脏脂肪体中，在雌性和雄性的所有发育阶段中，都有一些单个细菌细胞散落在脂肪细胞之间。在和之间，以及在其他各种蟑螂物种中，细菌细胞的分布模式非常相似，这可能反映了在进化过程中，蟑螂与共生菌之间高度保守的联系。我们的研究为实验研究城市害虫进化的起源和过程奠定了基础，因为微生物伴生物可能参与其中。
