Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 17, 2005
Publication Date: September 1, 2005
Citation: Handoo, Z.A., Skantar, A.M., Carta, L.K., Erbe, E.F. 2005. Morphological and molecular characterization of a new root-knot nematode, meloidogyne thailandica n.sp. (nematoda: meloidogynidae), parasitizing ginger (zingiber spp.). Journal of Nematology. 37(3):343-353. Interpretive Summary: Nematodes are microscopic worms that cause ten billion dollars of crop loss in the United States each year. Root-knot nematodes are very important root parasites that seriously damage many economic and other plants worldwide. A major problem with determining the extent of crop loss due to plant-parasitic nematodes is that the nematodes present in many areas are unknown. In the present study, ARS scientists from Beltsville, Maryland, discovered a new species of root-knot nematode infecting ginger roots that had been shipped to San Francisco from Thailand. They also discovered how to distinguish this new species from closely related species with anatomical and DNA sequence data. The results are significant because they provide the details necessary for scientists to identify this new and potentially invasive species wherever it may occur in the world. This research will be used by scientists, action agencies, and extension agencies engaged in nematode research and control.
Technical Abstract: A root-knot nematode Meloidogyne thailandica n. sp. was discovered on roots of ginger (Zingiber spp.) from Thailand intercepted in October 2002, by APHIS at the port of San Francisco from Thailand. Comparison by LM and SEM to three other morphologically related species (M. incognita, M. arenaria, and M. megatyla) revealed that the new species differs from these by one or more of the following: body, tail and hyaline tail length, shape of head, tail and tail terminus of second-stage juveniles; stylet length and shape of spicules in males; and in the perineal pattern and stylet length and shape of knobs in females. The distinctive perineal pattern is smooth with coarse striae; the dorsal arch is high and sometimes round to rectangular; and striae in and around the anal area form a thick network-like structure interrupted by a prominent lateral line and large distinct phasmids. Second-stage juveniles have a long slender tail with inflated rectum and long gradually tapering hyaline tail part, ending in rounded terminus. Male spicules have a bidentate terminus. Molecular data from the ribosomal LSU D3 expansion segment revealed four haplotypes, two of which were unique and distinguish M. thailandica n. sp. from M. arenaria, M. incognita and M. javanica. Additional information regarding distribution of this nematode is needed.