Insect aggregations and entomopathogenic nematode occurrence

Entomopathogenic nematodes of the family Steinernematidae may significantly reduce insect populations. They inhabit most terrestrial habitats and thei r prevalence can be influenced by biotic factors. Some sawfly species, the geometrid and noctuid moth complexes, and bibionid and sciarid flies charac teristically aggregate as diapausing or hibernating larvae in the soil. A s urvey for entomopathogenic nematodes from habitats characterized by these a ggregations was performed in the Czech Republic by collecting soil samples and utilizing Galleria traps in the laboratory. Steinernematids were recove red from 61 of 87 (70.1%) sampled localities. Seven Steinernema species, S. kraussei, S. feltiae, S. affine, S. intermedium, S. bicornutum and two des ignated as species B and F were identified. Among these, S. kraussei was pr evalent in sawfly localities (77.8%) while, in winter moth localities, S. f eltiae (55.6%) dominated and S. kraussei (22.2%) and S. affine (25.9%) were common. Soil-dwelling insect aggregations seem to provide an opportunity f or entomopathogenic nematode multiplication.