Distribution of entomopathogenic nematodes (Steinernematidae and Heterorhabditidae) in natural habitats in California, USA

A total of 270 soil samples from 30 different habitats in 10 geographic reg ions of California were evaluated for the presence of rhabditid entomopatho genic nematodes. Nematodes were isolated from 26.3% of the samples. The rec overed isolates were identified as Steinernema carpocapsae, S. feltiae, S. kraussei, S. longicaudum, S. oregonense, Heterorhabditis marelatus and H.ba cteriophora. Among the steinernematids, S. kraussei and S. feltiae were the most commonly encountered species, generally occurring in acidic soils hig h in organic matter. Among the heterorhabditids, H. bacteriophora was isola ted along the southern coast, whereas H. marelatus was recovered along the northern coast of California. Steinernematids were recovered from coniferou s forests, oak woodlands and grasslands whereas heterorhabditids were isola ted from coastal marshes.