Nematodes in the genus
can infect and kill slugs and snails, which are important agricultural pests. This useful trait has been commercialized by the corporation BASF after they mass produced a ...product labeled Nemaslug®. The product contains
, which has been cultured with
, a bacterial strain that was originally thought to be responsible for causing mortality in slugs and snails. The exact mechanism leading to death in a
infected host is unknown but may involve contributions from nematode-associated bacteria. The naturally occurring microbial community of
is unexplored; the previous
microbial community studies have focused on laboratory grown or commercially reared nematodes, and in order to obtain a deeper understanding of the parasite and its host interactions, it is crucial to characterize the natural microbial communities associated with this organism in the wild. We sampled
,
, and
directly from their habitats in Central and Southern California nurseries and garden centers and identified their native microbial community
16S amplicon sequencing. We found that the
microbial community was influenced by species, location, and possibly gastropod host from which the nematode was collected. The predominant bacteria of the
isolates collected included
,
, Aeromonadaceae, Pseudomonadaceae, and
.
isolates exhibited an enrichment with species belonging to Acinetobacter or Pseudomonadaceae. However, further research must be performed to determine if this is due to the location of isolate collection or a species specific microbial community pattern. More work on the natural microbial community of
is needed to determine the role of bacteria in nematode virulence.
Summary
In the period from August to October 2018, 140 specimens of the Spanish slug, Arion vulgaris, were collected from Podbrezje, Slovenia. Slugs were dissected and examined for the presence of ...parasitic nematodes within the cadavers. Identification of the nematodes was conducted using morphological and molecular techniques and confirmed the presence of Phasmarhabditis papillosa. This is the first record of P. papillosa from the mollusc host, A. vulgaris. Laboratory experiments aimed at testing the efficacy of P. papillosa against A. vulgaris were conducted using nematodes grown in vivo. Nematodes were applied at concentration rates of 50, 100 and 200 nematodes slug−1, respectively. Three weeks following treatment, the mortality of slugs was confirmed in all treatments (50 nematodes slug−1, 37.4 ± 2.7%; 100 nematodes slug−1, 48.4 ± 2.7%; 200 nematodes slug−1, 50.6 ± 2.7%). However, the pathogenesis of P. papillosa was observed first in the treatments with the lowest nematode dose at 4 days after treatments, while a decrease in the feeding behaviour of slugs was noted first in the treatments with the highest nematode dose. Future opportunities for the potential use of P. papillosa as a biological control agent against slugs are discussed. This is the first report of P. papillosa from Slovenia, and of its virulence against A. vulgaris.
Phasmarhabditis papillosa
is a promising biocontrol agent of gastropods in crops. To enhance the efficacy of mollusc parasitic nematodes, a better understanding of the chemical signalling between ...hosts and parasites is needed. The objective of this research was to test the stimulus–response behaviour of the mollusc parasitic nematode
P. papillosa
towards mucus of the following mollusc species:
Arion vulgaris
,
Limax maximus
,
Deroceras reticulatum
, and
Helix pomatia
. The nematode chemotactic response was observed as directed motility towards mucus of the tested mollusc species at two temperature regimes under laboratory conditions. The motility of
P. papillosa
was more strongly expressed at a higher temperature (20 °C) than at a lower temperature (15 °C). When comparing mucus of different mollusc species, none of the tested molluscs significantly affected the directed motility of
P. papillosa
at the lower temperature (15 °C). At the higher temperature (20 °C), mucus samples from
L. maximus
and
H. pomatia
were observed to be more attractive than those from
A. vulgaris
or
D. reticulatum
for the nematodes. Our results indicate that
P. papillosa
distinguishes among mollusc species by exhibiting a chemotactic response to a signal emanating from mollusc mucus.
The genus Phasmarhabditis is an economically important group of rhabditid nematodes, to which the well-known slug-parasite P. hermaphrodita belongs. Despite the commercial use of Phasmarhabditis ...species as an attractive and promising approach for pest control, the taxonomy and systematics of this group of rhabditids are poorly understood, largely because of the lack of diagnostic morphological features and DNA sequences for distinguishing species or inferring phylogenetic relationship. During a nematode sampling effort for identifying free-living relatives of Caenorhabditis elegans in Huizhou City, Guangdong, China, a novel species belonging to the genus Phasmarhabditis was isolated from rotting leaves. Detailed morphology of the gonochoristic P. huizhouensis sp. nov. was described and illustrated. The adult female has a robust body, a relatively short and wide buccal capsule conjoined by a rhabditiform pharynx. Females are characterized by a short cupola-shaped tail end bearing a slender pointed tip, with the junction flanked by a pair of 'rod-like' phasmids. Males have an open peloderan bursa that is supported by 9 pairs of genital papillae and 1 terminal pair of phasmids. P. huizhouensis sp. nov. is morphologically very similar to the type species Phasmarhabditis papillosa but is distinguishable by its male caudal traits. The new species is readily differentiated from other taxa in the genus by its female tail shape. Molecular phylogenetic inferences based on small subunit (SSU) and the D2-D3 domain of large subunit (LSU) ribosomal DNA genes reveal that P. huizhouensis sp. nov. forms a unique branch in both phylogenies which is genetically related to P. hermaphrodita and other parasites such as Angiostoma spp. The host associations of P. huizhouensis sp. nov. and its ability to parasitize slugs are unknown.
Between July and September 2021, researchers collected 100 specimens of the Spanish slug, Arion vulgaris, and dissected their cadavers to examine them for parasitic nematodes. Molecular techniques ...were used to identify the nematodes, which confirmed the presence of Oscheius myriophilus, marking the first recorded instance of this nematode in a gastropod host. To test the virulence of Slovenian strains of O. myriophilus and Phasmarhabditis papillosa and their effects on the feeding behavior of the Spanish slug, grey field slug (Deroceras reticulatum), and vineyard snail (Cernuella virgata), laboratory bioassays were conducted using nematodes grown in vivo. Nematodes were applied at various doses ranging from 10 to 500 nematodes/gastropod. The results showed that O. myriophilus and P. papillosa caused significant mortality (82.5% ± 2.5% at 15 °C) of the Spanish slug while being less effective against the vineyard snail and grey field slug. Nematodes were more virulent at a lower temperature (15 °C) than at the higher temperature (20 °C) tested in the experiment. Additionally, both nematode species significantly reduced gastropod herbivory. The potential use of O. myriophilus and P. papillosa as biological control agents against gastropods is discussed.
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