NATURAL OCCURRENCE OF ENTOMOPATHOGENIC NEMATODES (RHABDITIDA, STEINERNEMATIDAE AND HETERORHABDITIDAE) IN SPANISH SOILS

Entomopathogenic nematodes (Steinernematidae and Heterorhabditidae) we re surveyed in Spanish soils using the Galleria baiting technique. A t otal of 750 soil samples were taken from 150 sites representing differ ent regions and habitat types (cropland, woodland, and pasture). Entom opathogenic nematodes were recovered from 35 sites; 33 sites were posi tive for the occurrence of steinernematids and 2 sites for heterorhabd itids. Five distinct morphological types of steinernematids were recov ered: Steinernema feltiae (Filipjev), Steinernema carpocapsae (Weiser) , Steinernema affinis (Bovien), and two other Steinernema spp. Heteror habditis bacteriophora Poinar was the only species of this family isol ated in this survey. S. feltiae was the most common species found (23 sites). There was not a significant association between sampling time (spring/autumn) and frequency of nematode recovery. Nematodes were iso lated from coastal areas (0 m elevation) to high altitude areas (2000 m). Annual median temperature and rainfall had little association with the presence of nematodes. Soil moisture and temperature regimes are more important factors in determining the prevalence of these entomopa thogenic nematodes. They were associated with soils with udic moisture regimes and cryic temperature regimes. Nematodes were more frequently recovered from cropland soils than from woodland and pasture soils, b ut differences between habitat type were not significant. (C) 1996 Aca demic Press, Inc.