• Proceedings of the Korean Society of Soil Zoology Conference
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• 2004.11a
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• pp.15-16
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• 2004

• Korean journal of applied entomology
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• v.38 no.3
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• pp.255-260
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• 1999

Pathogenicity and multiplication of entomopathogenic nematode, Steinernema carpocapsae Weiser, ere analyzed in two insect hosts, Spodoptera exiga (Hubner) and Sp. litura(Fabricius). The estimated ${LC}^{50}s$(lethal concentration of the infective juveniles to kill 50% of the host insect population) were not different between tow insect species or among their developmental stages on the filter paper assay, thought the actual numbers of the infected nematodes were varied among them. The significant variation, however occurred in nematode multiplication between tow inset hosts. Temperature also gave sosignificatn effect on nematode multiplication rate that it took 6 days after infection at $25^{\circ}C$, but did 12 days at $20^{\circ}C$ to show the maximal nematode population peak($\approx$500,000 infective juveniles(IJ) in a 5th instar larva of Sp. litura and $\approx$-100,000 IJ in a 5th instar larva of Sp. exigua).

• Korean journal of applied entomology
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• v.51 no.1
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• pp.9-18
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• 2012

The size of infective $Steinernema$ $arenarium$ juveniles is variable and ranges from 724 to 1408 ${\mu}m$. Effects of harvest time and infective juvenile size on pathogenicity, development, and reproduction were examined in the last instar of the great wax moth, $Galleria$ $mellonella$. Harvest time of infective juveniles (IJs) of $S.$ $arenarium$ affected pathogenicity. IJs harvested at the 10th day from trapping were more pathogenic than those harvested the 3rd day from trapping. Mortality of $G$. mellonella also depending on harvest time, $i.e$, 100% died within 48h when IJs were harvested at the 10th day, without relation to size. However, mortality was 40% in the small size group (SSG) compared with 18% in the large size group (LSG) within 48h when IJs were harvested at the 3rd day. Establishment of $S.$ $arenarium$ within the host was different depending on IJ size. The number of established IJs was 1.8 in the SSG, 3.3 in the LSG, and 3.2 in the mixed size group (MSG) when IJs were harvested at the 3rd day, and 5.3 in the SSG, 7.4 in the LSG, and 7.6 in the MSG when IJs were harvested at the 10th day. The length of the female adult was 7,070.5 ${\mu}m$ in the SSG and 7,893.9 ${\mu}m$ in the LSG and that of the male was 1,460.5 ${\mu}m$ in the SSG and 1,688.2 ${\mu}m$ in the LSG when IJs were harvested at the 3rd day. The length of the female adult was 7,573.6 ${\mu}m$ in the SSG and 8,305.4 ${\mu}m$ in the LSG and that of the male adult was 1,733.4 ${\mu}m$ in the SSG and 1,794.4 ${\mu}m$ in the LSG when IJs were harvested at the 10th day. Harvest time and size of IJs did not influence numbers of progeny or size of IJS.

• KSBB Journal
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• v.13 no.1
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• pp.31-37
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• 1998

A simple method for the in vivo production of third-stage infective juveniles(IJs) of Steinernema glaseri was developed. Using Galleria mellonella larvae, only IJs can be rapidly generated inadequate quantities for field application. The nematode inoculation concentration and incubation temperature were critically important. The most effective temperature for infectivity of Steinernema glaseri IJs to Galleria mellonella larvae was 33$^\circ C$. However, the total number of menatodes harvested at 25$^\circ C$ about 66,000 IJs per larva was significantly greater than those at other temperatures. The optimal inoculation number of nematodes was 60 to 80 nematodes per host larva. The higher nematode inoculation concentration of 100 IJs per larva caused a rapid decrease in the total number of IJs harvested. As the inoculation medium pH increased, the number of IJs harvested increased and reached about 110,000 IJs per larva at pH 9.0. The pathogenicity of IJs decreased y increasing the salt concentration in the medium.

• Asian Journal of Turfgrass Science
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• v.13 no.4
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• pp.213-222
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• 1999

The toxic effects of four pesticides on the entomopathogenic nematodes. Heterorhabditis bacteriophora NC strain, Steinernema glaseri NC and Dongrae strain were tested by checking the mortality of infective juveniles(Ijs) in aqueous solution of pesticide. Mortality of Ijs was influenced by pesticide and concentration and soaking time. The herbicide alachlor and insecticide fenitrothion were toxic to Ijc of three entomopathogenic nematodes. But, the fungicides mepronil and tolclofos-methyl were nontoxic to Ijs. Tolclofos-methyl showed significantly very week toxicity at 28 days after soaking for S. glaseri NC strain. H. bacteriophora NC strain was more highly sensitive to high temperature condition then were the other nematodes.

• Korean journal of applied entomology
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• v.40 no.1
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• pp.59-67
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• 2001

The potential of two entomopathogenic nematodes, Sreinernema carpocapsae Pocheon strain and Heterorhabditis bacteriophora Hamyang strain as biological control agents was evaluated against mushroom ny, Lycoriella mali in laboratory and field. Mortality of L. mali was significantly different according to nematode species, concentration, temperature, and developmental stage of fly S. carpocapsae was more effective than H. bacteriophora. Mortality of L. mali was higher at $25^{\circ}C$ than at $20^{\circ}C$. In addition, the 3rd instal and the 4th instar of L. mali were more susceptible than the 2nd instar. The lowest $LC^{50}$ value was represented by S. carpocapsae, 20.0 infective juveniles (Ijs) in the 3rd instar, 27.5 Ijs in the 4th instar at $25^{\circ}C$. S. carpocapsae infected all the developmental stages of L. mali except egg stage and the 1st instar of larva. The highest mortality was shown in adult female representing 74.0% at$20^{\circ}C$ and 80.0% at $25^{\circ}C$.L. mali female adult was influenced by S. carpocapsae in oviposition. The number of eggs by L. mali female infected by nematodes was much lower than uninfected females. S. carpocapsae was dispersed by infected L. mali adult with higher numbers by females than males. When S. carpocapsae was applied at the rate of $2.25{\times}10^{5}\;and\;4.5{\times}10^{5}\;Ijs/1.5\;\textrm{m}^2$ in the mushroom house, mortalities were 42.2% and 81.6%, respectively. The infective juveniles of nematodes survived for 14 days in the mushroom medium. However, nematodes did not affect mushroom growth.

• The Korean Journal of Pesticide Science
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• v.10 no.2
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• pp.107-116
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• 2006

Korean entomopathogenic nematode strain were evaluated against white grubs, Popillia quadriguttata, Ectinohoplia rufipes and Phyllopertha diversa in laboratory. In addition we examined the efficacy of entomopatogenic nematode, Heterorhabditis sp. KCTC 0991BP strain against white grubs in Seaside Golf Club in Gimpo, Gyeonggii and persistence of entomopatogenic nematode in fairway of Anyang Benest Golf Club in Gunpo, Gyeonggii. In laboratory Heterorhabditis bacteriophora Hamyang strain showed 95% mortality against Popillia quadriguttata. H. bacteriophora Hamyang strain and Heterorhabditis sp. KCTC 0991BP induced 80% mortality against 3rd instar of Ectinohoplia rufipes. However, the letter showed only 60% mortality against Phyllopertha diversa. White grub density was reduced to 39% by the application of Heterorhabditis sp. KCTC 0991BP at the rate of $2.24{\times}10^9$ infective juveniles $ha^{-1}$ compared with control in Seaside Golf Club. Heterorhabditis sp. KCTC 0991BP persisted for two months at $5{\sim}10$ cm soil depth but not persisted at $0{\sim}5$ cm soil depth for the same periods when applied at the rate of $2.47{\times}10^9$ infective juveniles $ha^{-1}$.

• The Korean Journal of Pesticide Science
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• v.10 no.4
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• pp.335-343
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• 2006

Five strains of Korean entomopathogenic nematodes(EPN), steinernematids and heterorhabditids(Steinernama carpocapsae GSN1, Steinernema sp. GSNUS-10, Steinernama sp. GSNUS-14, Heterorhabditis bacteriophora Hamyang, Heterorhabditis sp. GSNUH-1) were evaluated and tried in petri dish, pot, and vegetable greenhouses for environmentally friendly control of beet armyworm, Spodoptera exigua. $LC_{50}$ values of five EPN strains against beet armyworm was different depending on nematode strain and beet armyworm instar. $LC_{50}$ value of Steinernema carpocapse GSN1(GSN1) was 3.8-5.1 infective juveniles(Ijs) in 2nd to 4th instars of beet armyworm. Pathogenicity of five EPN strains against beet armyworm different in nematode strain, concentration, application times, and vegetable species in pot and greenhouse. Steinernema spp. was more effective than Heterorhabditis spp. against beet armyworm. Two or three times of applications of EPN were found to be effective regardless of nematode strain and concentration in pot and greenhouse. ENP showed different reactions on vegetable species. Efficacy of EPN was higher on Chinese cabbage than that on cabbage and kale. GSN1 was one of the most effective nematodes and 100,000 infective juveniles per $m^2$(720,000 Ijs/$7.2m^2=1{\times}10^9$Ijs/ha) resulted in higher mortality in greenhouse.

• 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.

• Microbiology and Biotechnology Letters
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• v.29 no.2
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• pp.104-109
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• 2001

The yield of infective juveniles of Heterorhabditis bacteriophora (Tf strain) in vitro monoxenic liquid culture was improved significantly as the amount of symbiont biomass, Photorhabdus sp. strain Tf, increased. To investigate the influence of abiotic factors on the growth and biomass production of Photorhabdus sp. strain Tf, triplicate flask cu1tmes were performed. The optinal temperature and medium pH for the growth of Photorhahdus sp. strain Tf were 30$^{\circ}$C and between pH 5.5-7.3, respectively. Aeration also improved greatly growth and yield of biomass of Photorhabdus sp. strain Tf. Photorhabdus sp. strain Tf in batch fermentation showed growth-associated pattem in terms of pigment production, and the pH of culture medium rose steadily until growth stopped dUling the fermentation. Both pigment production and culture pH rise would be useful parameters indicating a reliable growth of Photorhabdus sp. strain Tf.