• Korean Journal Plant Pathology
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• v.3 no.3
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• pp.164-167
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• 1987

The effects of infection severity of susceptible tomato varieties, Rutgers and Boksu 2, by root-knot nematode, meloidogyne hapla, M. arenaria or M. javanica on plant growths and tomato yields were investigated. The inoculum levels of each nematode species were 0, 1,000 and 10,000 nematodes per 42cm diam. pot. Tomato yield was reduced by the nematode infection. Severity of infection was on the decreasing order of M. javanica, M. incognita, M. arenaria, M. hapla, ranging from $80\%$ by M. javanica to only $7\%$ by M. hapla. Yield reduction by infection of M. hapla was more prominent in Boksu 2 than in Rutgers. However the results were vice versa for the other nematode species, The top fresh-weight of Rutgers inoculated with 10,000 nematodes was greater than root weight, regardless of the nematode species, whereas plant height and top fresh weight decreased with increasing root weight when inoculated with inoculum density of 1,000/pot.

• The Plant Pathology Journal
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• v.35 no.6
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• pp.654-661
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• 2019

The soybean cyst nematode, Heterodera glycines, is a major plant-parasitic nematode that has caused important economic losses to Korea's soybean production. Four species of cyst nematodes, H. schachtii, H. glycines, H. trifolii, and H. sojae, all belong to schachtii group are coexist in field soil in Korea. The rapid identification of the nematode is crucial for preventing crop damage and in decision making for controlling this nematode. This study aimed to develop a species-specific primer set for quantitative PCR (qPCR) assay of H. glycines. The specific primer set (HGF1 and HGR1) for H. glycines was designed based on the cytochrome c oxidase subunit I (COI) sequence of mitochondrial DNA. After optimization, it is possible to identify the H. glycines using a qPCR assay with DNA extracted from a single cyst and single second-stage juvenile (J2). The specificity was confirmed by the absence of SYBR fluorescent signals of three other Heterodera species. A serial dilution of DNA extracted from a single cyst was obtained for the sensitivity test. The result showed that the standard curve of the test had a highly significant linearity between DNA concentration and Ct value (R² = 0.996, slope = -3.49) and that the detection limit concentration of DNA of the primer set was 10 pg of DNA per reaction. Our findings suggested that H. glycines could be distinguished from H. sojae and other Heterodera species when a qPCR assay is used with a specific primer set.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.359-359
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• 2017

A new soybean cyst nematode, H. sojae was reported from Korea in 2016. This species is closely related to H. glycines which has the same host plant. Morphological observations of the cyst, female, male and second-stage juveniles indicated that this species is differed from H. glycines. Especially, cysts of H. sojae appeared more round, shining and darker than that of H. glycines. The distribution of this new cyst nematode in soybean field in Korea is unknown so far. In 2016, 270 soil samples were collected from soybean fields and examined the existence of H. glycines and H. sojae. Total of 111 samples contained cysts (41.1%). Among them 77% were H. glycines and 23% were H. sojae. H. sojae is future threatening in soybean production area.

• Fisheries and Aquatic Sciences
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• v.19 no.5
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• pp.26.1-26.8
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• 2016

Background: The nematode species belonging to genus Anisakis occur at their third larval stage in numerous marine teleost fish species worldwide and known to cause accidental human infection through the ingestion of raw or undercooked fish or squids. They may also draw the attention of consumers because of the visual impact of both alive and dead worms. Therefore, the information on their geographical distribution and clear species identification is important for epidemiological survey and further prevention of human infection. Results: For identification of anisakid nematodes species isolated from largehead hairtail (Trichiurus japonicus), polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of internal transcribed spacers of ribosomal DNA were conducted. Mitochondrial cytochrome c oxidase subunit 2 gene was also sequenced, and phylogenetic analysis was conducted. From the largehead hairtail (n = 9), 1259 nematodes were isolated in total. Most of the nematodes were found encapsulated throughout the viscera (56.2 %, 708/1259) or moving freely in the body cavity (41.5 %, 523/1259), and only 0.3 % (4/1259) was found in the muscles. By PCR-RFLP, three different nematode species were identified. Anisakis pegreffii was the most dominantly found (98.7 %, 1243/1259) from the largehead hairtail, occupying 98.7 % (699/708) of the nematodes in the mesenteries and 98.1 % (513/523) in the body cavity. Hybrid genotype (Anisakis simplex ${\times}$ A. pegreffii) occupied 0.5 %, and Hysterothylacium sp. occupied 0.2 % of the nematodes isolated in this study. Conclusions: The largehead hairtail may not significantly contribute accidental human infection of anisakid nematode third stage larvae because most of the nematodes were found from the viscera or body cavity, which are not consumed raw. But, a high prevalence of anisakid nematode larvae in the largehead hairtail is still in concern because they may raise food safety problems to consumers. Immediate evisceration or freezing of fish after catch will be necessary before consumption.

• The Plant Pathology Journal
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• v.34 no.4
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• pp.297-307
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• 2018

The sugar beet cyst nematode, Heterodera schachtii is a well known pathogen on Chinese cabbage in the highland fields of Korea. However, a race of cyst forming nematode with close morphological resemblance to H. trifolii was recently isolated from the same Chinese cabbage fields. Morphological species differentiation between the two cyst nematodes is challenging, with only minor differences between them. Thus, this study described the newly intercepted H. trifolii population, and reviewed morphological and molecular characteristics conceivably essential in differentiating the two nematode species. A comparison of morphometric measurements of both infective juveniles and vulval cones of cysts showed significant differences between the two cyst nematodes. When total RNA and genomic DNA were extracted from a mixed field population, COI genes and ITS regions were clearly amplified with primers of the two Heterodera species, suggesting that Heterodera population collected from the Chinese cabbage field consisted of a mixture of two species. COI and ITS of H. trifolii were predominantly amplified from nucleotides prepared from H. trifolii monoxenic population whereas those of H. schachtii were strongly detected in H. schachtii monoxenic cultures. Thus, this study confirms the coexistence of the two species in some Chinese cabbage fields; and the presence of H. trifolii in Korea is reported here for the first time.

• Research in Plant Disease
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• v.16 no.1
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• pp.10-20
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• 2010

Root-knot nematodes cause billions of dollars in crop losses annually have a broad range of host over 2,000 species of plants. These nematodes are known as obligate, sedentary endo-parasites in a plant host to feed upon to complete their life cycle. To prevent the plant parasitic nematode, methyl bromide was widely applied as a soil fumigant. Other strategies to prevent or control nematodes involve RNAi-mediated suppression, R gene transformation, natural products or chemical treatments, the expression of peptide or proteins in susceptible plants, and others. Over the last decade, the entry in GenBank for Meloidogyne reveals 73,340 ESTs and recently two complete Meloidogyne spp. genomes sequences have simultaneously been presented by two groups. Recent works have demonstrated the effect of RNAi suppression to nematode target genes. These results will provide novel members of genes as a foundation for studies focused on understanding the function of M. incognita nematode genes as well as for the development of novel target genes for parasite control. Thus the successful development of biotechnology-derived plants with nematode resistance will result in large yield benefits for producers as well as environmental benefits and will accelerate the research related to pathogensresistant crops.

• Korean journal of applied entomology
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• v.31 no.4
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• pp.427-451
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• 1992

The nematodes associated with forest trees were surveyed in the National Parks and Mountains in Korea. A total of 73 species on 28 genera were identified from rhizosphere of 154 tree s species. Platycarya strobilacea, Ulmus davidiana and Acer ginnala were known to new host p plants of Meloinema kerongens. Bursaphelenchus xylophilus was detected only in Pusan on Pi$\pi$us t thunbergii, B. mucronatus was detected in Cheju, Masan, and Chinhae. Insect parasitic nemat todes, Prothallonema intermedium, on P. rigida in Daegu, P. thunbergii in Cheju city, Namwonu up, Gujoa-up and Aewol-up. The number of nematode species according to forest trees was t the highest on P. thunbergii to 32 species, followed by 24 species on Abies holophylla, 20 species on Zelkova serrata, 19 species on Diospyros kaki, 18 species on Quercus acutissima, respectively. L Localities of distribution according to nematode species were as follows; Crico$\pi$emella i$\pi$formis i in 81, X. americanum in 74, Tylenchorhynchus claytoni in 51, C. macrodora in 35, H Hemicriconemoides varionodus and Ogma serratum in 31, Pararotylenchus pini in 25, H Hemicycliophora koreana in 24, Aphelenchus avenae and C. pseudohercyniensis in 24, respectively.

• Journal of Species Research
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• v.5 no.3
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• pp.503-513
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• 2016

Two unrecorded marine nematode species, belonging to genus Paracanthonchus Micoletzky, 1924, are described on the basis of the specimens collected from rocky intertidal seagrass bed on the eastern coast of Korea. Paracanthonchus macrodon (Ditlevsen, 1918) is characterized by presence of cuticular differentiation, strongly dilated gubernaculum with numerous cusps, three post-cloacal setae, and arrangement of six (4+2) precloacal supplement. Paracanthonchus kamui Kito, 1981 is distinguished from other species of the genus by having the 4.25 turns amphideal fovea, six tubular supplement, rib-shaped gubernaculums with proximally hook-shaped and distally broaden. In this study, we provide taxonomic description and illustration of two unrecorded species of the genus Paracanthonchus by differential interference contrast microscopy. This is the first report on the species of the genus Paracanthonchus from Korea.

• Korean journal of applied entomology
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• v.27 no.3
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• pp.165-170
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• 1988

Taxonomical study on the Longidoridae from korea were undertaken at Kyungsangbuk-do. Three species belomging to two Longidoridae were identified. Xiphinema zulu, X. setatiae and Longidoridae sylphus were newly reported from Korea.

• Journal of Microbiology and Biotechnology
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• v.17 no.3
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• pp.420-427
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• 2007

We investigated the temperature effects on the virulence, development, reproduction, and otility of two Korean isolates of entomopathogenic nematodes, Steinernema glaseri Dongrae strain and S. longicaudum Nonsan strain. In addition, we studied the growth and virulence of their respective symbiotic bacterium, Xenorhabdus poinarii for S. glaseri and Xenorhabdus sp. for S. longicaudum, in an insect host at different temperatures. Insects infected with the nematode-bacterium complex or the symbiotic bacterium was placed at $13^{\circ}C,\;18^{\circ}C,\;24^{\circ}C,\;30^{\circ}C,\;or\;35^{\circ}C$ in the dark and the various parameters were monitored. Both nematode species caused mortality at all temperatures tested, with higher mortalities occurring at temperatures between $24^{\circ}C\;and\;30^{\circ}C$. However, S. longicaudum was better adapted to cold temperatures and caused higher mortality at $18^{\circ}C$ than S. glaseri. Both nematode species developed to adult at all temperatures, but no progeny production occurred at $13^{\circ}C\;or\;35^{\circ}C$. For S. glaseri, nematode progeny production was best at inocula levels above 20 infective juveniles/host at $24^{\circ}C\;and\;30^{\circ}C$, but for S. longicaudum, progeny production was generally better at $24^{\circ}C$. Steinernema glaseri showed the greatest motility at $30^{\circ}C$, whereas S. longicaudum showed good motility at $24^{\circ}C\;and\;30^{\circ}C$. Both bacterial species grew at all tested temperatures, but Xenorhabdus sp. was more virulent at low temperatures $(13^{\circ}C\;and\;18^{\circ}C)$ than X. poinarii.