• 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.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.4
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• pp.369-374
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• 1987

This study was conducted to evaluate the degree of acid tolerance of indigenous Rhizobium in natural soils, and to select the superior Rhizobia for legume forage on hilly land. 153 Rhizobial strains isolated from two host genera, Medicago and Trifolium in the pastures of Yeongnam area were screened on acidic agar plates. The results obtained are summarized as follows: 1. The degrees of acid tolerance of R. meliloti and R. trifolii were ranged from 4.3 to pH 5.5 and from 4.0 to pH 5.5 respectively. 2. Among acid tolerant Rhizobia isolates, two strains of R. meliloti at pH 4.3 and three strains of R. trifolii at pH 4.0 were shown to have the activities of nodulation and nitrogenase. 3. R. trifolii strains were shown to survive about 80 to 99% at the pH range 4.8 to 5.0, while R. meliloti were about 35 to 47% at that pH range. Therefore, more acid tolerant R. meliloti should be developed for legume forage in Korean hilly land.

• Korean journal of applied entomology
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• v.39 no.3
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• pp.153-156
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• 2000

Spatial activities of Liriomyza trifolii (Burgess) were investigated weekly using yellow sticky trap which were placed at three different height and monitored during four time periods. Yellow sticky trap placed at plant height caught significantly more L. trifolii (Burgess) than did traps placed at 30 and 60cm above plant height. Diel activities of L. trifolii (Burgess) were monitored with yellow sticky traps at 1- and 2-h intervals during three time periods. Leafminer flight activity in May, July and October peaked from 1400 to 1800 hours, 0800 hours and from 1200 to 1400 hours, respectively. 2nd peak of flight activity only occurred in May. Attraction of L. trifolii (Burgess) for yellow sticky traps was affected by temperature as well as solar intensity. Male of L. trifolii (Burgess) appeared more responsive to yellow sticky traps than female regardless of trap height or time of day.

• Korean Journal of Organic Agriculture
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• v.27 no.3
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• pp.353-363
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• 2019

To identify four cyst nematodes (Heterodera schachtii, H. trifolii, H. glycines, H. sojae) that are economically important plant-parasitic nematodes in Korea, restriction fragment length polymorphism (RFLP) by 8 endonucleases (PstI, VspI, AlwI, RsaI, MvaI, EcoRI, Eco72I, Hinf I) was performed based on sequence difference of mitochondrial DNA cytochrome c oxidase subunit I (COI) gene. As a result, species-specific DNA band patterns by RsaI endonuclease were observed in H. schachtii. The specific patterns was in H. trifolii by 3 endonucleases (VspI, AlwI, Hinf I), and was in H. glycines by Hinf I. While, H. sojae was not digested by 4 endonuclease (VspI, AlwI, RsaI, Hinf I). This study showed that four cyst nematodes could be distinguished using RFLP by 4 endonucleases (RsaI, VspI, AlwI, Hinf I) based on the sequence difference of COI gene.

• Korean journal of applied entomology
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• v.41 no.1
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• pp.61-65
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• 2002

This study was conducted to investigate percentage of parasitism and control effect of Liriomyza trifolii by Hemiptarsenus zilahisebessi on tomato. Percentages of parasitism on L. trifolii larva by ectopatasitoids war e 26∼45% Among them the parasitism by H. zilahisebessi was highest as 47∼75% in tomato. The parasitoids preferred 1 st to 3rd instar of host larvae. In laboratory test, the parasitoids showed high parasitism on 3rd instar larvae of host by 89.8∼93.1% when the female parasitoids were introduced by the ratios of 1 : 10, 1 : 20, and 1 : 30. In field test, 3 or 5 female parasitoids were introduced per plant. In the case, the parasitism increased to 80% 4 weeks after introduction of the parasitoids. This increased parasitism was resulted from density reduction of the host larvae There were no significant differences in parasitism, density of alive host, and percentage of damaged leaf between inoculation density.

• Korean journal of applied entomology
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• v.41 no.1
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• pp.21-25
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• 2002

Longevities of Hemiptarsenus zilahisebessi, ectoparasitoid of Liriomyza trifolii (Burgess) larva. were 23.0, 16.9. and 12.7 days at 20, 25, and 30$^{\circ}C$, respectively. The adults copulated and laid eggs as soon as they emerged at 20$^{\circ}C$ and 30$^{\circ}C$. The total number of eggs laid and the daily oviposition rate were 82.3/3.6, 90.3/6.0, and 95.5/7.8 at the three different constant temperatures. The sex ratios were 0.37,0.43. and 0.43 at 20,25, and 30$^{\circ}C$. respectively. Female oviposited 1.4 eggs near parasitized host larva and the average distance between eggs of H. zilahisebessi andhost larva wre 0.92mm. The instrinsic increase rates(r$\sub$m/) of H. zilahisebessi were 0.12, 0.19 and 0.27, and net reproduction were 31.0, 40.2, and 40.8 at 20,25, and 30$^{\circ}C$, respectively. Female of H. zilahisebessi oviposited mainly on the 3rd larva and sex ratio was 0.42, wheras the ratio was declined to 0.1 on the 1st larva.

• The Korean Journal of Pesticide Science
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• v.15 no.2
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• pp.87-96
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• 2011

To study solar activated insecticide, three types of dihydroxyl phosphorus(V) triazatetrabenzocorrole derivatives ($P(OH)_2TBCs$) including H, 4'-methoxy phenoxy, 4'-tert butyl phenoxy substituents were synthesized. The results show that slightly red-shift with introducing substituents was observed and singlet oxygen was generated by the sunlight. Based on photochemical properties, solar activated insecticidal activity tests against Liriomyza trifolii (Burgess) were carried out. Overall insecticidal activities were 100~85.7% in the concentration of 500ppm, and especially in the case of compound $P(OH)_2TBC$ the insecticidal activities was 100%.

• Korean journal of applied entomology
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• v.59 no.4
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• pp.361-369
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• 2020

This study aimed to investigate the differences in the effects of nematicidal materials (Burkholderia rinojensis, fluazaindolizine, fluopyram, fosthiazate, hydrogen peroxide, and imicyafos) on eggs and larvae of the sugar beet cyst nematode, Heterodera schachtii and clover cyst nematode, H. trifolii, which have recently become problematic in highland Chinese cabbage cultivation areas in Korea. Comparison of the hatching rates according to the test materials showed differences between treatments. In the treatment with fluopyram, fosthiazate, and imicyafos, a very high hatching inhibitory effect of 99% was observed in both nematodes, and there was no difference in the efficacy of treatments between nematode species except for that with hydrogen peroxide. Regarding the nematocidal activity of treatments against hatched larvae, only the fluazaindolizine treatment, despite showing a high hatching inhibitory effect, showed a low nematicidal effect of less than 30% against both nematodes, whereas a mortality rate of more than 90% was observed in the other treatments. There was no difference between nematode species in the reactions of the 2nd instar juveniles to all nematicidal test materials after 24 and 48 h of treatment. Although there are limitations to the laboratory experiment, the reaction to the nematicidal materials of the two cyst nematodes that damage the same host was similar, and simultaneous control is suggested in the areas where the two nematodes occur together.

• The Plant Pathology Journal
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• v.35 no.1
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• pp.90-90
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• 2019

• 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.