Molecular detection and quantification of slug parasitic nematodes from the soil and their hosts

Thirty years of slug control using the parasitic nematode Phasmarhabditis hermaphrodita and beyond

Several slug species are highly pestiferous and threaten global sustainable agriculture. Current control methods rely heavily on metaldehyde pellets, which are often ineffective, harm nontarget organisms and have been banned in some countries. A viable alternative is the parasitic nematode Phasmarhabditis hermaphrodita (and recently P. californica), which has been formulated into a biological control agent (Nemaslug®) to control slugs across northern Europe. Nematodes are mixed with water and applied to soil where they seek out slugs, penetrate behind the mantle and kill them in 4-21 days. Phasmarhabditis hermaphrodita has been on the market since 1994 and since then there has been ample research on its use. Here we review the research carried out on P. hermaphrodita over the last 30 years since its development and release as a commercial product. We provide information on life cycle, worldwide distribution, history of commercialisation, gastropod immunity, host range, ecological and environmental factors that affect its success in the field, bacterial relationships, and summarise results of field trials. Finally, we suggest future directions for P. hermaphrodita research (and other Phasmarhabditis species) to enhance its use as a biological control agent to control slugs for the next 30 years. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Phasmarhabditis thesamica n. sp. (Nematoda: Rhabditidae), a new slug nematode from southern slope of Caucasus, Georgia

Phasmarhabditis thesamica n. sp., belonging to the family Rhabditidae, was isolated from the bodies of the invasive slug, Deroceras reticulatum in Georgia. Nematodes of this genus have never been recorded previously in Georgia. Phasmarhabditis thesamica n. sp. was characterised at morphological, morphometrical and molecular level. Females are 2052 (1863-2241) μm long, lateral fields consisting of three protruding central ridges and four incisions. The vulval opening is in the middle of the body. The tail is conical, long, tapering to a filiform tip, with prominent rod-shaped phasmids. The reproductive system is didelphic-amphidelphic. Males are 1301 (1123-1456) μm long, with an open peloderal bursa, which is supported by nine pairs of genital papillae 1 + 1 + 1/2 + 1 + 3, and two phasmids located close to tail tip. The molecular phylogeny of P. thesamica n. sp. inferred by using ITS, D2-D3 expansion domains of the 28S rRNA gene and the 18S rRNA gene revealed close relationships with P. clausiliiae, with high support.