Naturally occurring entomopathogenic nematodes in the province of West-Flanders, Belgium

The presence of naturally occurring entomopathogenic nematodes (epns) was surveyed in the West-Flanders province in the north-west of Belgium. In 21 sites of different agronomical situations, 130 soil samples were taken. Using the Galleria larva bait technique, 16 soil samples were found positive for epns. Fifteen samples were found to contain Steinernema spp. (nine S. feltiae, five S. affinis, one Steinernema species B3). The remaining positive sample contained Heterorhabditis sp. (North West European strain). The morphometric characters of the isolates were highly variable and did not correspond precisely to the original descriptions; however, biochemical characterization confirmed their identity. The epns were isolated from 50%, 18.8% or 12.3% of the samples taken in sand dunes, grassland or woodlands, respectively. S. feltiae and S. affinis were isolated in these three habitats; Heterorhabditis sp. was found in a grassland habitat. Steinernema feltiae was prevalent in loamy sand soils with a wide range of organic matter content; S. affinis, Heterorhabditis sp. and Steinernema species B3 were isolated in sandy loam soils. All the positive sample sites were in the pH range of 4.0-8.1. This is the first report of naturally occurring entomopathogenic nematodes in Belgium.