Testing a new low-labour method for detecting the presence of Phasmarhabditis spp. in slugs in New Zealand

Most studies on distribution of Phasmarhabditis spp. in slugs use dissection of individual slugs, which is time-consuming. Here we use a technique modified from that used to collect Pristionchus spp. nematodes from their beetle hosts. Slugs are decapitated and cadavers incubated for 1 week prior to examining for presence of adult nematodes. We compared the new technique with traditional dissection using field-collected untreated slugs, and slugs infected with Phasmarhabditis hermaphrodita in the laboratory. There was no difference in the efficacy of the two techniques. We also used the new technique to study prevalence of P. hermaphrodita at 22 New Zealand sites. We found P. hermaphrodita present at three sites and P. californica at two other sites suggesting Phasmarhabditis spp. are relatively common in New Zealand.