南西諸島の恙虫相とその特徴〔英文〕

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南西諸島(種子島,屋久島,奄美大島,徳之島,与論島,沖繩,石垣島,西表島)の恙虫相を調査し,その特徴について検討した.特に恙虫病のvectorとなり得る恙虫種の存在と,採集方法として,各種の動物の巣坑道から土壌を採取し,Tullgren装置で未吸着幼虫を直接採集する"直接採集法"による調査を行った.得られた結果と過去の報告を加えると南西諸島で記録された恙虫は,21属55種であった(Table 8).この内,日本未記録属2種,新種11種,新記録種6種,南西諸島での新記録種は35種で,これまで未知の部分が多かった南西諸島の恙虫の様相が,本調査により可成り明確なものになった.旧北区の南端に位置する種子島,屋久島の恙虫は,Doloisia satoianaを除くすべてが九州本土産に一致するが,東洋区の北端,奄美大島産では7種が一致する他は,共通種が見出されない.また,奄美大島以南で採集された恙虫48種のうち日本本土産との共通種は10種だけであった.この事実は,トカラ海峡に引かれた生物分布境界線ワタセ線が他の動・植物に見られるように,恙虫相にも認められると考えられた.恙虫病のvectorとして既に我が国で確認されている恙虫のうち,南西諸島では,種子島のLeptotrombidium pallidum pallidum奄美大島のL. deliense,L. scutellareの3種が確認された.更にvectorの可能性が考えられる種として,屋久島,奄美大島,徳之島,沖繩本島のL. kawamurai奄美大島のL. akamushi近似種,L. p. burnsiの存在が分った.今回の調査に用いた直接採集法で32種の恙虫が採集され本法が従来行なわれている宿主採集法を充分補足出来るものと考えられた.宿主採集法によりアマミノクロウサギにはWalchia pentalagi,Cordiseta nakayamai,淡水産のカニにEutrombicula haematocheiriの宿主特異寄生恙虫が寄生していることが分った.Surveys on trombiculid fauna in Nansei Islands (Tanegashima, Yakushima, Amamioshima, Tokunoshima, Okinoerabu, Yoron, Okinawa, Ishigaki and Iriomote Islands) were undertaken and their peculiar characteristics were studied. The surveys were performed especially for confirmation of the mites which could be a vector of scrub typhus in the area. As a collecting method, Tullgren apparatus was employed, that is, soil samples were collected from nest tunnels of various animals and unengorged larval mites were directly collected by the apparatus (described as "Direct Method" hereafter). From results of surveys reported here and those of past reports, trombiculid mites recorded in Nansei Islands were found to be 55 species of 21 genera in total (Table 8). They are 14 species of 7 genera in Tanegashima and Yakushima Islands (Table 1), 40 species of 17 genera in Amami Islands (Amamioshima, Tokunoshima, Okinoerabu and Yoron Islands) (Table 3), 17 species of 10 genera in Ryukyu Islands (Okinawa, Ishigaki and Iriomote Island) (Table 5). Of them, there were 2 species of genus unrecorded in Japan, 11 new species, 6 species newly recorded in Japan and 35 species newly recorded in Nansei Islands. As a result, the surveys fairly clarified trombiculid fauna of Nansei Islands, which were considerably unknown hitherto. In islands of Tanegashima and Yakushima located at southern end of palaearctic region, all trombiculid mites, except Doloisia satoiana, were found corresponding to those in Kyushu main-land. Only 7 species of them, however, corresponded to those in Amamioshima Island located at northern end of oriental region. Out of 48 species found in area south of Amamioshima Island, only 10 species corresponded to those in Japan main-land. It was seemed, from the above results, that Watase-Line, a biological distribution boundary linning at Tokara channel, could apply also to trombiculid fauna as well as many other animals and plants. Among trombiculid mites which previously confirmed as vectors of, three species were confirmed distributing in Nansei Islands; Leptotrombidium pallidum pallidum in Tanegashima, L. deliense and L. scutellare in Amamioshima Island. Furthermore, as to be suspected vectors of the infection, L. kawamurai in Yakushima, Amamioshima, Tokunoshima and Okinawa, resemble species of L. akamushi and L. p. burnsi in Amamioshima were detected respectively. A new collecting method (the direct method) used in this survey had brought about 32 species of trombiculid mites in results. This indicates the new method can sufficiently substitute the usual host-collecting method. On the other hand, by the usual host-collecting method, peculiar trombiculid mites were collected such as Eutrombicula (Siseca) haematocheiri found in fresh water crabs, Walchia (Walchia) pentalagi and Cordiseta (Kayella) nakayamai specificaly found in Amami-Rabbit living only in Amamioshima and Tokunoshima Islands.
長崎大学熱帯医学研究所,Institute of Tropical Medicine, Nagasaki Universityの論文

南西諸島の恙虫相とその特徴〔英文〕

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