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Title: Two nematode species (Nematoda: Diplogastridae, Rhabditidae) from the invasive millipede Chamberlinius hualienensis Wang, 1956 (Diplopoda, Paradoxosomatidae)on Hachijojima island in Japan

Author
item Carta, Lynn
item THOMAS, WILLIAM - University Of New Hampshire
item MEYER-ROCHOW, VICTOR - University Of Oulu

Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2018
Publication Date: 12/1/2018
Citation: Carta, L.K., Thomas, W.K., Meyer-Rochow, V.B. 2018. Two nematode species (Nematoda: Diplogastridae, Rhabditidae) from the invasive millipede Chamberlinius hualienensis Wang, 1956 (Diplopoda, Paradoxosomatidae) on Hachijojima island in Japan. Journal of Nematology. 50(4):479-486. https://doi.org/10.21307/jofnem-2018-048.
DOI: https://doi.org/10.21307/jofnem-2018-048

Interpretive Summary: Although usually harmless to humans, millipedes contain pathogenic bacteria and may distribute plant and animal diseases. Moreover, when millipedes are introduced to new locations lacking their old parasites and predators, the resulting large numbers of millipedes may eat and damage crop plants. One approach to controlling invasive millipedes is to find and evaluate possible biological control organisms. In this paper, an ARS scientist and other researchers from Japan and the United States report the discovery of two new types of microscopic roundworms called nematodes within invasive, plant-eating millipedes that recently came to Japan from Taiwan. One worm is related to a biological control nematode that was used to control populations of another type of invasive millipede in Australia. The second worm is similar to one found in Switzerland one hundred years ago associated with beetles. Anatomical and DNA information for identifying and placing these nematodes within family trees are presented. These discoveries are significant, because one type of nematode has never been found in millipedes before and might be exploited as a possible biological control agent anywhere millipedes become a problem. This information will be used by researchers to better understand host and parasite associations to develop methods for an integrated control of invasive millipedes.

Technical Abstract: Millipedes may cause unexpected damage when they are introduced to new locations, becoming invaders that leave behind their old parasites and predators. Therefore it was interesting to find numerous rhabditid nematodes within the gut of the phytophagous millipede Chamberlinius hualienensi Wang, 1956 (Diplopoda, Paradoxosomatidae) from Hachijojima (Japan) in November, 2014. This invasive millipede originated in Taiwan but was discovered in Japan in 1986. These roundworms were identified as juvenile Oscheius sp. cf. necromenus (Rhabditidae), and juvenile and adult Fictor sp. cf. hessi (Diplogastridae) based on images, morphometrics, and sequences of 28S rDNA. A short 28S sequence of Oscheius necromenus SB218 from Australian millipedes was also included in phylogenetic comparisons of a species complex of millipede-associated Oscheius. An 18S rDNA sequence for Fictor was compared with the few related taxa found within GenBank as well. This population of Fictor had an adult male not present in the closest relative from Switzerland described a century ago. Other species in Fictor were associates of beetles, so this finding is an exceptional ecological association for this diplogastrid genus. The only other nematode associates of millipedes belong to Rhigonematida and Oxyurida, two strictly parasitic genera of nematodes.