Entomopathogenic nematodes occurring in forest habitats and their role in a forest ecosystem

在东京、箱根和德贺的森林中进行了调查，以确定昆虫病原线虫的发生情况，并阐明这些线虫在森林生态系统中沿着营养链的作用。对森林生境的土壤样品进行了线虫的检测，方法是用花廊线虫幼虫作诱饵。所有调查地点均有未被描述的斯坦纳马种。该线虫与毛线虫亲缘关系密切，但在形态和生物学上可与毛线虫区分开来。表明该线虫可能在日本东部的森林生境中分布广泛且常见。根据对线虫感染的廊虫幼虫的生命周期观察，可以认为该线虫具有冷活性。线虫在其自然栖息地的水平空间格局为斑驳或聚集。现有资料表明，该线虫在寻找寄主方面属于巡洋舰线虫。在特贺县玉川大学森林的落叶松林中，发生了落叶松锯叶虫病暴发，土壤中的锯叶虫幼虫自然感染了该线虫。这是在日本的锯蝇中首次发现该属的记录。

Surveys were done in forests located in Tokyo, Hakone and Tesikaga to determine the occurrence of entomopathogenic nematodes and to elucidate the role of these nematodes along a trophic chain within a forest ecosystem. Soil samples from forest habitats were tested for the presence of nematodes by baiting with Galleria mellonella larvae. An undescribed Steinernema species occurred at all sites surveyed. The nematode is closely related to S.feltiae, but it can be differentiated from S.feltiae by some morphological and biological characteristics. It was indicated that this nematode might be widely distributed and of common occurrence in forest habitats of eastern Japan. Based on the life cycle observed on nematode infected Galleria larvae, it could be concluded that this nematode was cold active. The horizontal spatial pattern of the nematode in its natural habitat was patchy or aggregated. The available data suggested that this nematode was a cruiser nematode as to its host finding behavior. In the larch forest of Tamagawa University Forest in Teshikaga where an outbreak of larch sawfly, Cephalcia sp.occurred sawfly larvae in soil were naturally infected with the nematode. This is the first known record of this genus in a sawfly in Japan.