Steinernema riojaense n. sp., a new entomopathogenic nematode (Nematoda: Steinernematidae) from Spain

A new species of entomopathogenic nematode, Steinernema riojaense n. sp., was isolated during a survey in La Rioja province of Spain. Morphological and morphometric traits place the new species in the glaseri-group, which is characterised by having the largest infective juvenile (IJ) with an average body length in excess of 1000 μm. The IJ of S. riojaense n. sp. possess a body length of 1043 (869-1172) μm, the lateral fields are formed by eight equally spaced and developed ridges (nine incisures) in the mid-body region, giving the formula 2, 6, 8, 4, the excretory pore is located posterior to the mid-pharynx region (D% = 58), and the hyaline region occupies ca half of the tail length. The male spicules are moderately curved with a sharp tip and are golden-brown in colour with the manubrium elongate and having a length to width ratio of 1.7:1. The first-generation male tail is non-mucronate, whereas a small papilla-like mucron is developed in the second generation. There are 11 pairs of genital papillae plus a single precloacal papilla. The first-generation female possesses a moderately protruding vulva and a slightly protruding postanal swelling. The second-generation female possesses a slightly protruding vulva and a postanal swelling. The new species is further characterised by sequences of the internal transcribed spacer (ITS) and partial 28S regions (D2-D3) of the ribosomal DNA (rDNA). Phylogenetic analyses confirm that S. riojaense n. sp. belongs to the glaseri-group and forms a monophyletic subclade with other European species.Peer reviewe

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

Terrestrial gastropod molluscs are widely distributed and are well known as pests of many types of plants that are notoriously difficult to control. Many species of nematodes are able to parasitize land snails and slugs, but few of them are lethal to their host. Species and/or populations of mollusc-parasitic nematodes (MPNs) that kill their hosts are promising for biological control purposes. The recent discovery of new nematode species of the genus Phasmarhabditis in Europe and the associations between Alloionema spp. and slugs are expanding the possibilities of using MPNs as control agents. However, very little is known about the distribution and ecology of these species. Using molecular techniques based on qPCR methods for quick identification and quantification of various species of MPN isolated directly from the soil or from infected hosts can assist in providing information on their presence and persistence, as well as the composition of natural assemblages. Here, we developed new primers and probes for five species of the genus Phasmarhabditis and one species of the genus Alloionema. We employed these novel molecular techniques and implemented a published molecular set to detect MPN presence in soil samples coming from natural and agricultural areas in Switzerland. We also developed a method that allows the detection and quantification of Phasmarhabditis hermaphrodita directly from the tissues of their slug host in a laboratory experiment. The new molecular approaches were optimized to a satisfactory limit of detection of the species, with only few cross-amplifications with closely related species in late cycles (>32). Using these tools, we detected MPNs in 7.5% of sampled sites, corresponding to forest areas (P. hermaphrodita and Alloionema appendiculatum) and wheat-oriented agricultural areas (Phasmarhabditis bohemica). Moreover, we confirmed that the method can be used to detect the presence of P. hermaphrodita inside slug hosts, with more detections in the susceptible slug Deroceras larvae compared to the resistant Arion vulgaris. These primers/probe sets provide a novel and quick tool to identify MPNs from soil samples and infected slugs without having to culture and retrieve all nematode life stages, as well as a new tool to unravel the ecology of nematode-slug complexes.This work was funded by the Swiss National Science Foundation: Grants NRP68 and SNSF Div. I-III, reference 166632. The Government of Spain supports RCH with a Ramón y Cajal contract award: RYC-2016-19939.Peer reviewe