Inundative biological control (biocontrol) efforts in pest management lead to the mass distribution of commercialized biocontrol agents. Many 'biocontrol gone awry' incidents have resulted in ...disastrous biodiversity impacts, leading to increased scrutiny of biocontrol efforts. The nematode Phasmarhabditis hermaphrodita is sold as a biocontrol agent on three continents and targets pest gastropods such as Deroceras reticulatum, the Grey Field Slug; P. hermaphrodita is not presently approved for use in the United States. Investigations into the potential for P. hermaphrodita to infect non-target gastropod species of conservation relevance, however, are limited. We examined the effects of three strains of P. hermaphrodita on mortality in Monadenia fidelis, the Pacific Sideband, a snail species endemic to the Pacific Northwest of North America, in laboratory conditions. Across a 71-day laboratory infectivity assay, snails exposed to each of the three nematode strains, each analyzed at two doses, experienced a mean 50% mortality by days 20-42. All nematode-treated snails were dead by the end of the study. By contrast, 30/30 water-control snails experienced no mortality. Nematodes killed smaller, juvenile-stage snails significantly faster than those in larger and more developmentally advanced hosts. Our results provide direct evidence that the biocontrol nematode P. hermaphrodita infects and kills M. fidelis, a non-target gastropod species endemic to the Pacific Northwest, in laboratory conditions. This study suggests that introduction of P. hermaphrodita to new ecosystems might negatively impact endemic gastropod biodiversity and advocates for further investigation of non-target effects, including in conditions closer to the natural environments of non-target species.
Performs a phylogenetic analysis of nematode mitochondrial DNA (mtDNA) strains representing eight different Phasmarhabditis species, collected from nine countries around the world, in order to ...identify the origin of species recently discovered in New Zealand and the western USA. Confirms that nematodes deriving from the Nemaslug® biocontrol product have invaded countries where its use as a biological control agent is prohibited by regulatory agencies and is not commercially available. Source: National Library of New Zealand Te Puna Matauranga o Aotearoa, licensed by the Department of Internal Affairs for re-use under the Creative Commons Attribution 3.0 New Zealand Licence.
The grey garden slug (
), a common terrestrial slug native to Europe with a global distribution including North America, is commonly considered the most severe slug pest in agriculture. The nematode
..., which has been used in the U.K. and Europe as a commercial biocontrol agent since 1994, has also recently been collected in Oregon and California and has long been considered a candidate biocontrol agent for slug management in the U.S. In this study, we report differential gene expressions in nematode-infected slugs using RNA-seq to identify slug immune-related genes against nematodes. Comparison of gene expression levels between the whole bodies of a nematode-infected slug (N-S) and an uninfected control slug (C-S) revealed that there were a total of 39,380 regulated unigenes, of which 3084 (3%) were upregulated and 6761 (6%) were downregulated at greater than 2-fold change (FC > 2) in the nematode-infected slug. To further investigate the biological functions of differentially expressed genes (DEGs), gene ontology (GO) and functional enrichment analysis were performed to map the DEGs to terms in the GO, eukaryotic ortholog groups of proteins (KOG) and Kyoto Encyclopedia of Genes and Genome Pathway (KEGG) databases. Among these DEGs, approximately 228 genes associated with immunity or immune-related pathways were upregulated 2-fold or more in the N-S compared to C-S. These genes include toll, Imd, JNK, scavenger receptors (SCRs), C-type lectins (CTLs), immunoglobulin-like domains, and JAK/STAT63 signaling pathways. From the RNA-seq results, we selected 18 genes and confirmed their expression levels by qRT-PCR. Our findings provide insights into the immune response of slugs during nematode infection. These studies provide fundamental information that will be valuable for the development of new methods of pest slug control using pathogenic nematodes in the field.
Invasive slugs and snails are among the most damaging pests of agriculture in temperate and tropical regions of the world. Control options, however, are limited and there is a heavy reliance on ...chemical molluscicides of variable efficacy. There is an ongoing need to improve management methods. Here, we show that a simple fermenting bread dough formulation (flour, water, and yeast) was effective in attracting pest mollusk species in laboratory tests, and in multiple replicated field trials in Hawaii, Oregon, and Montana. The dough attracted substantially more terrestrial pest gastropods, including invasive species of major economic importance such as
,
,
,
,
, and
, than water controls. The dough remained attractive for at least 8 days and was significantly more attractive than a widely used metaldehyde-based bait, Deadline
M-Ps™. Thus, fermenting bread dough represents a nontoxic, generic, and effective tool to aid in managing pest gastropod infestations, either using baited traps or in attract-and-kill approaches. Given its simplicity, low cost, and the ready availability of its ingredients, the dough also has potential to be used in developing countries where access to commercial molluscicide baits is limited by cost.
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•Three recently discovered nematode species in the US kill the slug D. reticulatum.•The extent of and time to cause complete mortality varied between nematode species.•Phasmarhabditis ...papillosa appears to be the most lethal to D. reticulatum.
Slugs such as Deroceras reticulatum (Müller) are among the most important pests of agricultural production throughout North America. Current control strategies are unreliable and this has resulted in increased interest and research on biological control options using nematodes in the genus Phasmarhabditis which have been recently discovered in the U.S. Herein, the lethality of U.S. strains of P. hermaphrodita (Schneider), P. californica Tandingan De Ley, Holovachov, Mc Donnell, Bert, Paine and De Ley, P. papillosa (Schneider) and an undescribed species of Phasmarhabditis at two inoculation rates were investigated for the first time, against D. reticulatum in laboratory infectivity trials. Our data shows that three of the nematode species (P. hermaphrodita, P. californica and P. papillosa) are lethal to D. reticulatum but the extent of and time to cause complete mortality varied. In terms of slug survival (LT 50) and median percentage slug mortality, P. papillosa demonstrated the most lethality in the trials, and the undescribed species the least. However, before an informed decision can be made on the use of these nematodes as effective and safe biological control agents, there are many additional knowledge gaps that need to be filled. Of particular importance will be comprehensive host range testing that incorporates native gastropod species.
The nematode Phasmarhabditis hermaphrodita is lethal to a wide range of pest gastropod species. In Europe, it is available as a biocontrol agent (Nemaslug®), but its complete host range is yet to be ...determined. Our data showed that a U.S. strain of this nematode is lethal to the introduced, non-pest, subterranean slug, Testacella haliotidea, which substantiates the broad host range of P. hermaphrodita. These data highlight the need for completing additional testing with both pest and particularly native gastropod species before a decision is made on the use of P. hermaphrodita as a biocontrol agent in the U.S.
Slugs and snails are widely distributed in natural humid habitats, and they are a worldwide problem in agriculture. The grey garden slug, a common terrestrial species, is considered the most severe ...pest of vegetables and field crops. Currently, the most common slug control methods rely on chemical pesticides, which can be damaging to the environment and human health. Nematodes are important natural enemies of slugs, and one species has been used as a commercial product for three decades. This study investigated and analyzed the differential gene expression profiles between nematode-infected slugs and uninfected slugs and identified the genes associated with immunity in the grey garden slug. The results provide a starting point for understanding the molecular mechanism of immune genes and physiological pathways, facilitating the identification of biological targets for slug management strategies in the field. The grey garden slug (Deroceras reticulatum ), a common terrestrial slug native to Europe with a global distribution including North America, is commonly considered the most severe slug pest in agriculture. The nematode Phasmarhabditis hermaphrodita , which has been used in the U.K. and Europe as a commercial biocontrol agent since 1994, has also recently been collected in Oregon and California and has long been considered a candidate biocontrol agent for slug management in the U.S. In this study, we report differential gene expressions in nematode-infected slugs using RNA-seq to identify slug immune-related genes against nematodes. Comparison of gene expression levels between the whole bodies of a nematode-infected slug (N-S) and an uninfected control slug (C-S) revealed that there were a total of 39,380 regulated unigenes, of which 3084 (3%) were upregulated and 6761 (6%) were downregulated at greater than 2-fold change (FC > 2) in the nematode-infected slug. To further investigate the biological functions of differentially expressed genes (DEGs), gene ontology (GO) and functional enrichment analysis were performed to map the DEGs to terms in the GO, eukaryotic ortholog groups of proteins (KOG) and Kyoto Encyclopedia of Genes and Genome Pathway (KEGG) databases. Among these DEGs, approximately 228 genes associated with immunity or immune-related pathways were upregulated 2-fold or more in the N-S compared to C-S. These genes include toll, Imd, JNK, scavenger receptors (SCRs), C-type lectins (CTLs), immunoglobulin-like domains, and JAK/STAT63 signaling pathways. From the RNA-seq results, we selected 18 genes and confirmed their expression levels by qRT-PCR. Our findings provide insights into the immune response of slugs during nematode infection. These studies provide fundamental information that will be valuable for the development of new methods of pest slug control using pathogenic nematodes in the field.
Marsh flies are a diverse family that provide valuable ecosystem services, including the biological control of mollusks that are agricultural pests and vectors of animal and human parasitic diseases. ...In addition, some species may serve as important ecological bioindicators. Despite the extensive research on this family, most have centered on larval diet and behavior, as this is the life stage primarily used for biological control; virtually nothing is known about the natural dietary components of adult marsh flies. Our study aimed to close this knowledge gap by examining the dietary range and preference of adult marsh fly species. Individual flies were provided with five food choices in cafeteria-style food choice trials, consisting of crushed snail, freshly killed slug, glucose solution, honey-yeast mixture (the standard laboratory rearing diet), or water. Sciomyzidae at family level displayed significant differences in food selection (P = 0.0212), with carbohydrates (honey-yeast and glucose solution) significantly preferred over protein options (mollusk tissue) or the water control (P < 0.001). This suggests that marsh flies may naturally maintain a carbohydrate-rich diet. Because many plants typical at field sites produce little or no nectar, a second experiment aimed to determine the source of these carbohydrates in nature. When presented with honeydew harvested from aphids (Hemiptera: Auchenorrhycha), Tetanocera elata Fabricius (Diptera: Sciomyzidae) individuals were observed to feed on dry honeydew and honeydew solution significantly more frequently than the water control (P < 0.001 and P = 0.01969, respectively), suggesting that honeydew may play an important role in adult marsh fly diet.
The nematode Phasmarhabditis hermaphrodita is lethal to a wide range of pest gastropod species. In Europe, it is available as a biocontrol agent (Nemaslug®), but its complete host range is yet to be ...determined. Our data showed that a U.S. strain of this nematode is lethal to the introduced, non-pest, subterranean slug, Testacella haliotidea, which substantiates the broad host range of P. hermaphrodita. These data highlight the need for completing additional testing with both pest and particularly native gastropod species before a decision is made on the use of P. hermaphrodita as a biocontrol agent in the U.S.
Donald Wellerstein is best known as a founder of the Cleveland Quartet, though his reputation as a teacher eclipses his fame as a player. With appointments at both Juilliard and the New England ...Conservatory, teaching takes an increasing amount of Wellerstein's time. He talks about his empathic approach to teaching.
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