The chemotactic response of Phasmarhabditis hermaphrodita (Nematoda: Rhabditidae) to cues of Deroceras reticulatum (Mollusca: Gastropoda)

Entomopathogenic nematodes use a range of cues released by insects to locate hosts but there has been no research on how the slug-parasitic nematode, Phasmarhabditis hermaphrodita, finds potential hosts. We exposed P. hermaphrodita to a range of cues associated with the highly susceptible host Deroceras reticulatum. Cues included foot and mantle mucus and faeces from live D. reticulatum and volatile cues released from this slug. We also compared the attractiveness of live and dead D. reticulatum, and the attractiveness of infected and non-infected D. reticulatum. Phasmarhabditis hermaphrodita responded poorly to volatile cues but was strongly attracted to live D. reticulatum, its faeces and mucus from both the foot and mantle. Phasmarhabditis hermaphrodita was attracted more to dead than live hosts, and was equally attracted to infected and non-infected D. reticulatum. The strong attraction to dead D. reticulatum adds weight to the hypothesis that this nematode is a facultative parasite that is capable of growth and reproduction on decaying plant and animal material present in soil.