Natural occurrence of entomopathogenic nematodes in North China

摘要

The diversity and distribution of entomopathogenic nematodes (EPN) in North China was studied during 2007 and 2008. A total of 2780 soil samples were taken from six provinces (Shanxi, Henan, Jilin, Liaoning, Heilongjiang and Inner Mongolia). Two hundred and five sites were positive for the occurrence of EPN; 103 isolates were steinernematids and 102 isolates were heterorhabditids. Morphological, morphometric and molecular data were used to identify the nematode species. Seven species of Steinerematidae were found: Steinernema feltiae (Filipjev, 1934) Wouts, Mracek, Gerdin & Bedding, 1982, S. ceratophorum Jian, Reid & Hunt,1997, S. longicaudum Shen & Wang, 1992, S. litorale Yoshida,2004, S. hebeiense Chen, Li, Yan, Spiridonov & Moens, 2006, S. carpocapsae (Weiser, 1955) Wouts, Mracek, Gerdin & Bedding, 1982, and S. monticolum Stock, Choo & Kaya, 1997. Three Heterorhabditis species were obtained: i.e., Heterorhabditis bacteriophora Poinar, 1976, H. megidis Poinar, Jackson & Klein, 1987, and H. indica Poinar, Karunakar & David, 1992. There were also three undescribed Steinernema species which were distinct from known steinernematids in morphological, morphometric and molecular characteristics. According to the morphological traits of their IJ and males, these three species should be classified in the S. feltiae group. The EPN were recovered from a wide range of habitats including both natural and agricultural habitats. Nematodes were isolated from plain areas (38 m elevation) to high altitude areas (1723 m). The survey indicated that the occurrence of different nematode species was strongly associated to the prevailing climatic conditions, altitude, vegetation and soil types.