Habitat preference for entomopathogenic nematodes, their insect hosts and new faunistic records for the Czech Republic

Steinernematids and heterorhabditids are widespread soil nematodes. The dependence of their distribution on habitat type, soil texture, soil pH, and altitude has been studied in some detail, while much less is known about how their occurrence depends on the abundance and habitat preference of their insect hosts. Here we surveyed the entomopathogenic nematode fauna of the Czech Republic and evaluated the impact of ecosystem type, habitat, soil, season, altitude, and insect host species on their prevalence. We also examined the effect of temperature on their isolation rates in the laboratory. Nine species of the genus Steinernema (S. kraussei, S. feltiae, S. affine, S. carpocapsae, S. intermedium, S. arenarium, S. bicornutum, S. weiseri, and S. silvaticum) and two of the genus Heterorhabditis (H. bacteriophora and H. megidis) were recorded for the Czech Republic. Nematodes occurred in all ecosystems and habitats tested. They were more abundant in tree habitats and light soils and in sites with abundant suitable insect hosts; seasonality and altitude had no significant impact on their occurrence. At two laboratory temperatures (15 and 22 °C) different numbers of isolates were obtained from the Galleria bait traps. Abundance of entomopathogenic nematodes in soil samples varied considerably and there were at most five baiting replicates (in habitats with many suitable insect hosts).