Isolation and characterisation of Heterorhabditis spp. (Nematoda: Heterorhabditidae) from Hungary, Estonia and Denmark

Targeted surveys were conducted for the entomopathogenic nematode Heterorhabditis in areas of Denmark, Estonia and Hungary. Isolates were identified by IEF, PCR and cross-fertility tests as belonging to three distinct taxonomic groups: H. bacteriophora, the north-west European (NWE) type of H. megidis and the Irish type of Heterorhabditis. The Irish and NWE types of Heterorhabditis were both present in Denmark (at six and four sites, respectively), while only the NWE type was recovered in Estonia. H. bacteriophora was the dominant heterorhabditid identified in Hungary (ten sites), but the Irish type was also detected at two sites. This is the first report of the Irish type of Heterorhabditis on Continental Europe. Co-occurrence of two Heterorhabditis types at a single site was noted in Denmark (Irish and NWE) and in Hungary (Irish and H. bacteriophora). Heterorhabditis was recovered at 38.5% of sites (n = 26) in Denmark (north coast of Sjaelland), 27.3% of the coastal sites (n = 22) in Estonia, and 32.6% of sites (n = 46) in Hungary.