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 Belgiu m. In 21 sites of different agronomical situations, 130 soil samples w ere taken. Using the Galleria larva bait technique, 16 soil samples we re found positive for epns. Fifteen samples were found to contain Stei nernema spp. (nine S. feltiae, five S. affinis, one Steinernema specie s B3). The remaining positive sample contained Heterorhabditis sp. (No rth 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 i dentity. The epns were isolated from 50%, 18.8% or 12.3% of the sample s taken in sand dunes, grassland or woodlands, respectively. S. feltia e and S. affinis were isolated in these three habitats; Heterorhabditi s sp. was found in a grassland habitat. Steinernema feltiae was preval ent in loamy sand soils with a wide range of organic matter content; S . affinis, Heterorhabditis sp. and Steinernema species B3 were isolate d in sandy loam soils. All the positive sample sites were in the pH ra nge of 4.0-8.1. This is the first report of naturally occurring entomo pathogenic nematodes in Belgium.