<div xmlns="http://www.w3.org/1999/xhtml">
<p>Invasive European slugs damage a range of crops in North America, including canola, soybean, maize, wheat, strawberries, asparagus, Brussels sprouts, and ornamental plants (<a ref-type="bibr" href="#j_jofnem-2020-092_ref_003">Barker, 2002</a>). The status of slug and snail as pests has been growing globally, yet the widespread use of chemical control measures is less than ideal (<a ref-type="bibr" href="#j_jofnem-2020-092_ref_002">Bailey, 2002</a>; <a ref-type="bibr" href="#j_jofnem-2020-092_ref_016">Wilson and Rae, 2015</a>). Baited pellets and liquid sprays containing methiocarb, metaldehyde, iron phosphate, and sodium ferric EDTA sometimes fail to provide adequate protection for crops (<a ref-type="bibr" href="#j_jofnem-2020-092_ref_007">Hata et al., 1997</a>; <a ref-type="bibr" href="#j_jofnem-2020-092_ref_002">Bailey, 2002</a>). These products are also poisonous to birds, mammals, and invertebrates (<a ref-type="bibr" href="#j_jofnem-2020-092_ref_011">Purves and Bannon, 1992</a>; <a ref-type="bibr" href="#j_jofnem-2020-092_ref_005">Fletcher et al., 1994</a>; <a ref-type="bibr" href="#j_jofnem-2020-092_ref_002">Bailey, 2002</a>). In Europe and the UK, a biological control agent, <italic>Phasmarhabditis hermaphrodita</italic> (Nematoda: Rhabditidae) against slugs and snails has been formulated into a biological molluscicide (Nemaslug<sup>®</sup>) for horticultural and agricultural application (<a ref-type="bibr" href="#j_jofnem-2020-092_ref_006">Glen and Wilson, 1997</a>). This nematode is a facultative parasite that can complete its life cycle without a host; however infective stages can penetrate and infect slugs and snails. The larvae feed on the host and develop into adults, which are hermaphrodites and primarily oviparous (<a ref-type="bibr" href="#j_jofnem-2020-092_ref_010">Maupas, 1900</a>). The nematodes kill the host within 4 to 21 days and eventually produce a new generation (<a ref-type="bibr" href="#j_jofnem-2020-092_ref_006">Glen and Wilson, 1997</a>; <a ref-type="bibr" href="#j_jofnem-2020-092_ref_013">Tan and Grewal, 2001</a>). To date, no <italic>Phasmarhabditis</italic> species has been found in Canada, though a few species have been discovered in the United States, including <italic>P. hermaphrodita,</italic> plus two new species, <italic>P. californica</italic> and <italic>P. papillosa</italic> (<a ref-type="bibr" href="#j_jofnem-2020-092_ref_015">Tandingan De Ley et al., 2016</a>; <a ref-type="bibr" href="#j_jofnem-2020-092_ref_009">Mc Donnell et al., 2018</a>). These new finds have spurred interest in identifying a natural biological control agent against slugs in Canada.</p>
<sec id="j_jofnem-2020-092_s_001">
<div>Methods and results</div>
<p>A total of 2,406 slugs were collected from residential gardens and local nurseries during a survey in the greater area of Edmonton. Nine slug species (<italic>Arion fasciatus, A. hortensis, A. rufus, Prophysaon andersoni, Deroceras reticulatum, D. invadens, D. leave, Ambigolimax valentianus,</italic> and <italic>Limax maximus</italic>) were identified, representing three slug families (Arionidae, Agriolimacidae, and Limacidae). Slugs were returned to the lab and exterminated by severing the head, and placed individually in a petri dish lined with a moistened filter paper. The dishes were then incubated at 12 hr light, 18°C, 80% RH, and 12 hr dark, 12°C, 60% RH. The slugs were monitored over the course of two weeks for the presence of nematodes. Nematode samples were taken in triplicate and stored in 95% EtOH before molecular analysis. We found a putative <italic>Phasmarhabditis</italic> species in association with an <italic>Arion rufus</italic> slug (id verified by R. Mc Donnell, OSU), collected from the exterior grounds of a local nursery. PCR amplification and subsequent direct DNA sequencing of an ~800 bp segment of the nematode 18S ribosomal RNA gene revealed a sequence that was 100% match to the 18S rRNA sequence for <italic>P. californica</italic> (KM510210; <a ref-type="bibr" href="#j_jofnem-2020-092_ref_014">Tandingan De Ley et al., 2014</a>, <a ref-type="bibr" href="#j_jofnem-2020-092_ref_015">2016</a>) in GenBank. Our newly generated <italic>P. californica</italic> 18S sequence was submitted to GenBank under accession number MT135094.</p>
</sec>
<sec id="j_jofnem-2020-092_s_002">
<div>Discussion</div>
<p>This is the first study to report on the occurrence of <italic>P. californica</italic> in Canada. Our results highlight the need for further field surveys in Canada to determine the distribution and abundance of this nematode. The nematode <italic>P. californica</italic> was first described in association with a slug in California (<a ref-type="bibr" href="#j_jofnem-2020-092_ref_015">Tandingan De Ley et al., 2016</a>) and has recently been isolated in New Zealand (<a ref-type="bibr" href="#j_jofnem-2020-092_ref_017">Wilson et al., 2016</a>) and Europe (<a ref-type="bibr" href="#j_jofnem-2020-092_ref_004">Carnaghi et al., 2017</a>). The discovery of <italic>P. californica</italic> in Canada has potentially significant regulatory implications for pest management generally and specifically for biological control against a growing slug problem. Biological control has many advantages over chemical pesticides as it offers greater specificity while using fewer toxic chemicals. For example, <italic>P. hermaphrodita</italic> only attacks slugs and snails, and is harmless to other organisms, such as earthworms, birds, and beneficial insects (<a ref-type="bibr" href="#j_jofnem-2020-092_ref_012">Rae et al., 2007</a>). Research on the infectivity and host specificity of this Canadian strain against pestiferous and native gastropods is needed to determine its potential as a biological control agent in Canada. Furthermore, <italic>Phasmarhabditis sp.</italic>, a facultative parasite, could also be employed as new genetic model nematodes to study the evolution of parasitism (<a ref-type="bibr" href="#j_jofnem-2020-092_ref_001">Andrus and Rae, 2019</a>; <a ref-type="bibr" href="#j_jofnem-2020-092_ref_008">Luong and Mathot, 2019</a>).</p>
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First report of a gastropod parasitic nematode <italic>Phasmarhabditis californica</italic> (Nematoda: Rhabditidae) in Alberta, Canada

Journal of Nematology

This work is licensed under the Creative Commons Attribution 4.0 International License.

First report of a gastropod parasitic nematode  (Nematoda: Rhabditidae) in Alberta, Canada

First report of a gastropod parasitic nematode Phasmarhabditis californica (Nematoda: Rhabditidae) in Alberta, Canada

Published Online: Aug 25, 2020

Page range: 1 - 3

DOI: https://doi.org/10.21307/jofnem-2020-092

Keywords
Alberta, Biological control, Canada, Slug, PCR,

© 2020 Taylor Brophy et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

First report of a gastropod parasitic nematode Phasmarhabditis californica (Nematoda: Rhabditidae) in Alberta, Canada

Published Online: Aug 25, 2020

Page range: 1 - 3

DOI: https://doi.org/10.21307/jofnem-2020-092

KeywordsAlberta, Biological control, Canada, Slug, PCR,

© 2020 Taylor Brophy et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Keywords
Alberta, Biological control, Canada, Slug, PCR,