Natural variation in chemoattraction in the gastropod parasitic nematodes Phasmarhabditis hermaphrodita, P. neopapillosa and P. californica exposed to slug mucus

Phasmarhabditis hermaphrodita is a lethal parasite of several slug species and has been formulated into a biological control agent for farmers and gardeners. Phasmarhabditis hermaphrodita responds to slug faeces, mucus and volatile cues to find hosts in soil. However, these results have only focused on one strain of P. hermaphrodita (DMG0001). We exposed four strains of P. hermaphrodita (and DMG0001), three strains of P. neopapillosa and two strains of P. californica to mucus from seven common slug species. Furthermore, we investigated whether there was a relationship between chemoattraction and the numbers of offspring that were produced on each host species. Natural isolates of P. hermaphrodita differed in their preference of slug species whereas P. neopapillosa tended to prefer Arion sp. and strains of P. californica displayed striking differences in their responses. The reasons for positive chemoattraction to mucus were not due to higher numbers of offspring produced on these hosts.