• The Korean Journal of Soil Zoology
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• v.5 no.2
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• pp.97-100
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• 2000

We report here an improved collecting method of the infective juveniles multiplied in the host insect with the entomopathogenic nematodes, Steinernema carpocapsae Weiser. The specific characteristics of this method involved the opening of the host insect hemocoel after the population of their infective juveniles reached at the maximum (6 days at 25$\^{C}$ after nematode treatment to nonimmunized host insects) to facilitate the escape of the multiplied nematodes. It also used 'Baermann funnel'method to select the infective juveniles effectively. This improved 'Baermann funnel'method was compared with a traditional collecting method, which was characterized with a combination of untreated host insects and 'White trap'collecting method, in both yield and pathogenicity of the collected infective juveniles to the fifth instar larvae of beet armyworm, Spodoptera exigua (H bner). More than 95% of the nematode populations collected by the two methods represented the morphological infective juveniles. To prove the nematodes to be infective juveniles functionally, pathogenicity and infective activity were compared in the nematodes collected by the two methods. They were not different in both pathogenicities and infective activities which were measured by the numbers of nematodes penetrated into the hemocoel of the insect hosts after exposure for the specific times to the same dote of infective juveniles. Significant difference between two collecting methods was found in the total yields of the infective juveniles per host insect About 50,000 infective juveniles per infected fifth instar larva of S. exigua after 6 day incubation at 25$\^{C}$ were collected only for 2 days by the improved 'Baermann funnel'method, while about 20,000 infective juveniles per host were collected for 10 days by the classical 'White trap'method.

• The Korean Journal of Pesticide Science
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• v.20 no.4
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• pp.293-299
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• 2016

Effect of nematicidal compounds on hatchability of sugar beet cyst nematode, Heterodera schachtii and its infective juveniles was investigated. The sugar beet cyst nematode was isolated from Chinese cabbage field in Samcheok in Korea. Acute toxicity of nematicidal compounds against infective juveniles was also tested to find the $LC_{50}$ by exposing juveniles to given dilutions of each compound. Hatchability and mortality of infective juveniles of H. schachtii were influenced by nematicidal compounds (Fluopyram 40% SC, imicyafos 30% SC, fosthiazate 30% SC, abamectine 1.68% SC, terthiophene, and Eclipta prostrata extract). Fluopyram and imicyafos yielded the lowest rates of hatching. Total hatched infective juveniles were significantly different among nematicidal compounds. Positive correlation in percentage reduction of hatching was observed in fluopyram. Furthermore, the highest mortality was also observed in the treatments of fluopyram and imicyafos ($LC_{50}$ of 0.0543 and 0.0178 ppm respectively). The study, therefore, demonstrated available alternative nematicidal compounds which could be used in the control of H. schachtii.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2000.04a
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• pp.201-207
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• 2000

The strategies of commercial development have been focused on the economy of scale for a process. The design of media has been recognized as a key in assuring mass production of entomopathogenic nematodes. Media optimization was conducted with insect host, proteins, lipids, and symbiotic bacteria mass. G. mellonella (insect host) produced about 290,000 infective juveniles per one. Complex media produced about 250,000 infective juveniles / ml in liquid culture within 8 days (one generation).

• The Korean Journal of Soil Zoology
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• v.8 no.1_2
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• pp.17-22
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• 2003

An endemic entomopathogenic nematode, Heterorhabditis megidis, was evaluated by its control efficacies against housefly, Musca domestica, and flower beetle, Gametis jucunda. In Petri-dish assay, the pathogenicity of H. megidis showed 456.4 infective juveniles/larva (IJs/larva) in median lethality (LC$_{50}$) against the second instar larvae of M. domestica and 238.9 IJs/larva against the second instar larvae of G. jucunda. This was contrasted with those of the other well-known entomopathogenic nematode, Steinernema carpocapsae, which showed 115.9 IJs/larva against M. domestica and 388.6 IJs/larva against G. jucunda. In field experiment, H. megidis were applied per square meter of pork farm with 1,000,000 IJs of H. megidis or apple orchard with 370,000 IJs, which were infested with M. domestica or G. jucunda, respectively. H. megidis showed 56.9% and 57.3% of control efficacies against M. domestica and G. jucunda, respectively. These results suggest a promising control technique in the field using H. megidis against M. domestica and G. jucunda.a.

• Korean journal of applied entomology
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• v.39 no.3
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• pp.149-152
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• 2000

Cryopreservation of infective juveniles of entomopathogenic nematode, Steinernema carpocapsae Weiser, was conducted at $-190^{\circ}C$ liquid nitrogen and its, efficacy was analysed on nematode survival and pathogenicity with glycerol pretreatments and storage periods. Infective juveniles were pre-treated before being frozen by incubating the nematodes in 22% glycerol for each of 6, 12, and 24 h, followed by 70% methanol at $0^{\circ}C$ for 10 minutes. Just after glycerol and methanol incubations, subsamp1es of the nematodes were resuspended in 0.85% saline and maintained during 24h for viability determination. Different glycerol incubation periods significantly affected the nematode susceptibility to methanol infiltration. Six hour incubation in glycerol resulted in much less nematode survival than did 12 h or 24 h incubation. About 70% of the infective juveniles frozen at $-190^{\circ}C$ for 5 months, preincubat-ed in glycerol at least for 12h, were able to survive after being resuspended in 30°C saline. They did not also show any change in their pathogenicity during cryopreservation. These results suggest an improved technique for long-term storage of the entomopathogenic nematodes.

• The Korean Journal of Pesticide Science
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• v.3 no.2
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• pp.60-68
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• 1999

Effects of temperature and dose-size on infectivity and reproduction of Korean entomopathogenic nematode, Steinernema longicaudum Gongju strain were examined. The greater wax mea Galleria mellonella larvae were exposed to 5, 10, 20, 40, 80, and 160 infective juveniles/larva in $60{\times}15$ mm petri dishes and kept in $13^{\circ}C$, $18^{\circ}C$, $24^{\circ}C$, and $30^{\circ}C$ incubators. Each petri dish contained one larva weighed from 180 to 200 mg. Infectivity was observed everyday for 14 days and reproduction for 30 days. The infectivity of S. longicaudum was more influenced by temperature than by dose-size. Mortalities by S. longicaudum were lower at $13^{\circ}C$ at all concentrations but higher at $24^{\circ}C$ and $30^{\circ}C$ even at lower concentrations, 5 or 10 infective juveniles/larva. Lethal time was also shorter with increasing temperature and dosages. All host larvae died at $24^{\circ}C$ and $30^{\circ}C$ in 2 days at the rate of 160 infective juveniles per host while 83.3% of tested larvae died at $24^{\circ}C$ in 10 days and 90% at $30^{\circ}C$ in 6 days at the rate of 5 infective juveniles. Reproduction was also better with increasing temperature and dosages. The highest number of progenies was obtained at $30^{\circ}C$ in 6 days at the rate of 80 infective juveniles. However, progenies were not produced from cadavers at $13^{\circ}C$. Reproductive period was the shortest at $30^{\circ}C$ of all temperatures by 6 to 9 days. The results indicated that optimum temperatures for infectivity was $24^{\circ}C$ and $30^{\circ}C$ for reproduction.

• Asian Journal of Turfgrass Science
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• v.19 no.1
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• pp.39-46
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• 2005

The 21 strains of Korean entomopathogenic nematodes, {Heterorhabditis bacteriophora Hamyang strain(HbH), Heterorhabditis sp. 202, 205, 217, Heterorhabdiris sp. KCTC 0991BP strain, Steinernema carpocapsae Pocheon(ScP), S. longicaudum Gonaju, S. longicaudum Nonsan, Steinernema sp. 7,24, 52, 55, 60, 64, 206, 207, 209, 210, 219, and 227 strain} were evaluated for the control of a turfgrass insect pest, Exomala orientalis. Heterorhabditis spp. showed higher pathogenicity than Steinernema spp. against 3rd instar larvae of E. orientalis with $55\%$ mortality by Heterorhabditis sp. 202 strain and $50\%$ by HbH and Heterorhabditis sp.205 strain at the rate of 200 infective juveniles per larva 14 days later after treatment. The number of infective juveniles of Korean entomopathogenic nematodes in 3rd instar larvae of E. orientalis was higher in Heterorhabditis spp. than in Steinernema spp.. In general, numbers of produced infective juveniles of three species were much higher, i.e., Heterorhabditis sp.202 strain produced 273,064 infective juveniles, S. carpocapsae Pocheon strain 273,043, and Heterorhabditis sp. 217 strain 248,887, respectively.

• Journal of Microbiology and Biotechnology
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• v.17 no.6
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• pp.968-978
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• 2007

A pathogenic nematode, Butlerius sp., was isolated from Oriental beetle, Blitopertha orientalis. The infective juveniles exhibited dose-as well as time-dependent entomopathogenicity on the larvae of B. orientalis. Two bacterial species, Providencia vermicola (KACC 91278) and Flavobacterium sp. (KACC 91279), were isolated from the infective juveniles and identified. P. vermicola outnumbered Flavobacterium sp. in the nematode host, in which the colony density of P. vermicola was found to be 21 times higher than that of Flavobacterium sp. However, when the two bacterial species were cocultured in culture media without the nematode host, they showed similar growth rates. Both bacteria induced significant entomopathogenicity against Spodoptera exigua larvae infesting economically important vegetable crops, where P. vermicola was more potent than Flavobacterium sp.

• Korean journal of applied entomology
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• v.44 no.2
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• pp.145-150
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• 2005

Three Korean isolates of entomopathogenic nematodes, Steinernema carpocapsae KCTC 0981BP (ScK), S. glaseri Dongrae (SgD), and Heterorhabditis sp. KCTC 0991BP (HsK), were evaluated for the control of a turfgrass pest, Popillia quadriguttata. Three days after treatment, all nematodes showed high pathogenicity to adult P. quadriguttata with $97.5\%$ mortality by ScK, $90.8\%$ by HsK, and $80\%$ by SgD at the concentration of 900 infective juveniles per adult. Nematode attachment and infection rate to adult P. quadriguttata were various depending on nematode species and inoculation density. The rate of nematode attachment was $90.8\%$ in HsK, $90.6\%$ in SgD, and $35\%$ in ScK, resfectively at the concentration of 900 infective juveniles per adult. The infection rate that represents the rate of detected nematode from inside insect of body was $97.5\%$ in ScK, $ 80\%$ in both HsK and SgD at the 900 concentration of infected juveniles. The infection rate, however, was decreased to $27.5\%$ in ScK, $72.5\%$ in SgD, but no nematodes was detected in HsK at the concentration of 90 infective juveniles.

• Korean journal of applied entomology
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• v.42 no.2
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• pp.145-152
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• 2003

Field application of the entomopathogenic nematode, Steinernema carpncapsae, is limited by its susceptibility to UV irradiation and desiccation especially at leaf spray control. This study was conducted to develop the control technique using alginate biocapsulation of the nematodes against the beet armyworm, Spodoprera exigua and the tobacco cutworm, Sp. litura that are normally infesting hosts above ground level. The alginate capsules including infective juveniles gave significant feeding toxicities to the larvae of the two lepidopteran species. The lethality followed a typical sigmoid dose-mortality pattern with increase of the nematode densities embedded in the capsules. Moisture content in the capsule was critical to the survival of the infective juveniles. More than 80% nematodes could survive above 10% moisture content remained in the capsule. Remaining moisture content within the capsule was dependent on relative humidity, ambient temperature, and capsule size, but not on citric acid reaction time during capsule formation. More than 80% of infective juveniles in the alginate capsules could survive in distilled water at 15$^{\circ}C$ for 60 days. When these nematode capsules containing welsh onion extract as another phagostimulant were applied on the 3rd instar larvae of Sp. exigua infesting peanut plants, they resulted in about 90% control efficacy. These results indicate that the alginate capsulation can be used for leaf-spray agent of the entomopathogenic nematodes as well as for improved storage purpose.