First record of a mermithid nematode (<scp>N</scp>ematoda:<scp>M</scp>ermithidae) parasitizing winged females of gall‐forming aphids (<scp>H</scp>emiptera:<scp>A</scp>phididae:<scp>E</scp>riosomatinae)

Genetic studies of nematodes have been dominated by Caenorhabditis elegans as a model species. Lack of genomic resources has been a limiting factor for expansion of genetic research to other groups of nematodes. Here, we report a draft genome assembly of a mermithid nematode, Mermis nigrescens. Mermithidae are insect parasitic nematodes with hosts including a wide range of terrestrial arthropods. We sequenced, assembled, and annotated the whole genome of M. nigrescens using nanopore long-reads and 10X chromium link-reads. The assembly is 524 Mb in size consisting of 867 scaffolds. The N50 value is 2.42 Mb, and half of the assembly is in the 30 longest scaffolds. The assembly BUSCO score from the eukaryotic database (eukaryota_odb10) indicates that the genome is 86.7% complete and 5.1% partial. The genome has a high level of heterozygosity (6.6%) with a repeat content of 78.7%. mRNA-seq reads from different sized nematodes (≤2 cm, 3.5-7 cm, and >7 cm body length) representing different developmental stages were also generated and used for the genome annotation. Using ab initio and evidence-based gene model predictions, 12,313 protein-coding genes and 24,186 mRNAs were annotated. These genomic resources will help researchers investigate the various aspects of the biology and host-parasite interactions of mermithid nematodes.

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First Report of Mermithidae (Enoplea: Mermithida) Parasitizing Adult Stable Flies in Japan

Shimizu,

Saito,

Takashima

et al. 2024

Journal of Nematology

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Mermithidae is a family of nematodes that parasitize a wide range of invertebrates worldwide. Herein, we report nematodes that were unexpectedly found in three of 486 adult stable flies (Stomoxys calcitrans) captured from three farms (F1, F2, and F3) in different regions of Gifu Prefecture, Japan. We aimed to characterize these nematodes both at the morphological and molecular level. Morphological studies revealed that the nematodes were juveniles of Mermithidae. Phylogenetic analysis based on 18S and 28S rDNA indicated that the mermithids from farms F1 and F2 could be categorized into the same cluster as Ovomermis sinensis and Hexamermis sp., whereas the mermithid from farm F3 clustered with Amphimermis sp. Additionally, these mermithids could be categorized within the same clusters as related mermithids detected in Japan that parasitize various arthropod orders. Our findings suggest that these stable flies may have been parasitized by mermithids already present in the region and that genetically distinct species of mermithids occur across Japan. To the best of our knowledge, this is the first report of mermithids parasitizing adult stable flies in Japan.

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First record of a mermithid nematode (Nematoda:Mermithidae) parasitizing winged females of gall‐forming aphids (Hemiptera:Aphididae:Eriosomatinae)

Cited by 3 publications

References 40 publications

Diversity and Systematics of Nematodes Used in Biocontrol

Diversity and Systematics of Nematodes Used in Biocontrol

Genome assembly and annotation of the mermithid nematodeMermis nigrescens

First Report of Mermithidae (Enoplea: Mermithida) Parasitizing Adult Stable Flies in Japan

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