Morishima Kaori, Nakano Takafumi, Aizawa Mineaki
United Graduate School of Agricultural Science Tokyo University of Agriculture and Technology Utsunomiya Japan.
Department of Zoology Graduate School of Science Kyoto University Kyoto Japan.
Ecol Evol. 2020 May 19;10(12):6030-6038. doi: 10.1002/ece3.6344. eCollection 2020 Jun.
Since the 1990s, increasing populations of a blood feeding land leech () have become a serious issue in several Japanese prefectures, and it may be caused by the increases in sika deer () populations seen over the last quarter of the century. Therefore, this study aimed to reveal the host animal species of . using iDNA (vertebrate DNA isolated from invertebrates) and to test the hypothesis that the increasingly widespread distribution of sika deer results in increased . populations through changes to the host-parasite interface. We amplified mitochondrial DNA 16S ribosome RNA fragments from iDNA isolated from the blood clots of . collected across Japan. We identified 17 host animal species, including four orders of Mammalia (Carnivora, Artiodactyla, Rodentia, and Lagomorpha) and two orders of Amphibia (Caudata and Anura). The sika deer was the dominant host species of . . Additionally, the host animal species composition of . differed according to the presence or absence of sika deer. In the sites where sika deer were not found, Anura (frog) species were the most commonly identified hosts of . . These results suggest that the increases in . populations might have occurred via a change in host preference to sika deer. This change might be driven by the increases in sika deer populations and subsequent increase in the frequency that . uses the sika deer as easy prey, as well as by sika deer providing more reproductive energy per blood meal than blood meal from frog species. The present study suggests that a more widespread distribution of sika deer resulted in an increase in . through a change in the host-parasite interface. Therefore, management that focuses on decreasing sika deer populations would likely be an effective method for the reduction of . populations.
自20世纪90年代以来，吸血陆蛭（）数量不断增加，已成为日本几个县的严重问题，这可能是由于上世纪最后25年里梅花鹿（）数量增加所致。因此，本研究旨在通过分析无脊椎动物中分离的脊椎动物DNA（iDNA）来揭示吸血陆蛭的宿主动物种类，并验证梅花鹿分布日益广泛导致宿主 - 寄生虫界面变化，进而引起吸血陆蛭数量增加这一假设。我们从在日本各地采集的吸血陆蛭血凝块中分离出的iDNA中扩增出线粒体DNA 16S核糖体RNA片段。我们鉴定出17种宿主动物，包括哺乳纲的四个目（食肉目、偶蹄目、啮齿目和兔形目）以及两栖纲的两个目（有尾目和无尾目）。梅花鹿是吸血陆蛭的主要宿主物种。此外，吸血陆蛭的宿主动物种类组成因有无梅花鹿而有所不同。在未发现梅花鹿的地点，无尾目（蛙类）是最常被鉴定出的吸血陆蛭宿主。这些结果表明，吸血陆蛭数量的增加可能是由于宿主偏好转向梅花鹿所致。这种变化可能是由梅花鹿数量增加以及随后吸血陆蛭将梅花鹿作为容易捕食对象的频率增加所驱动，同时梅花鹿每次吸血提供的繁殖能量比蛙类血液更多。本研究表明，梅花鹿分布范围扩大通过宿主 - 寄生虫界面变化导致吸血陆蛭数量增加。因此，以减少梅花鹿数量为重点的管理措施可能是减少吸血陆蛭数量的有效方法。
