恙蟲Trombicula akamushi (BRUMPT)の生態的觀察

概要

論文の詳細を見る
The larvae of Trombicula akamushi (BRUMPT), which are found in the conchae of field voles called Microtus montebelli that have been collected in districts where Tsutsugamushi disease is endemic, are classified into several forms. This classification is based on morphological characteristics. Thus, for instance, the one with fine bristles and another one with stout bristles are the forms most commonly found. The first mentioned form has been generally believed to be the vector of the disease, because it is found only in summertime, when the disease is prevalent, while the stout bristled forms have been collected all the year round. During the present investigation, however, the authors found that the fine bristled type as well as the stout bristled on live through all the seasons of the year, and furthermore that there is no seasonal difference between the one and the other form. The prosopon of the Trombicula akamushi lives in the superficial layers of the soil to the depth of about 18cm, though the depth of the soil at which they are actually found varies from season to season. As a rule they are found near the surface of the ground in the warm season and then go down to the lower soil's layers as the atmospheric temperature falls. But in winter, when the ground is covered with thick coat of snow, they come up again close to the surface. The mature eggs with their shell are found in the body of the prosopon from May to September and the larvae emerge during the same time of the year. The eggs that are found in the mature prosopon are relatively few in number (1-8). In summer the newly hatched larvae, if they attack the host, undergo a series of stages of development in the ground and reach the stage of prosopons in autumn and deposit eggs the following year. When the larvae get a chance to bite for instance field voles during the cold season, they develop into nymphochrysalis as usual, but their further development is not completed until late the following spring, when the hitherto hibernating nymphochrysalis become active and undergo the subsequent stages of development. If, having no chance to bite, the larvae remain unfed, they may live and retain the activity of biting for nearly one year. Therefore, the fact that human cases of Tsutsugamushi disease never occur in the cold season but only in summer is not on account of absence of the larvae in the field during the cold season, but the physical environment in the endemic region of this disease is the cause of it.
社団法人日本動物学会の論文
1936-10-15

恙蟲Trombicula akamushi (BRUMPT)の生態的觀察

スポンサーリンク

概要

著者

関連論文

スポンサーリンク