• Korean journal of applied entomology
• /
• v.40 no.3
• /
• pp.259-264
• /
• 2001

Toxicological studies of two potential biological control agents, the entomopathogenic nematode (Steinernema carpocapsae) and the symbiotic bacteria (Xenorhabdus nematophilus) were conducted against two beneficial insects and one mammal species. Two microbial agents varied in their toxicities between two insect species: an ant, Pristomyrmex pungens, and silkworm, Bombyx mori. In oral toxicity test, the symbiotic bacteria resulted in significant lethal [half lethal concentration of $1.4$\times$10^3$colony-forming units (cfu)/ml] on the ants, while they gave little lethal effect (half lethal concentration of more than $10^{8}$ cfu/ml) on the silkworms. The nematodes, however, gave significant lethal effect [half lethal concentration of 4 infected juveniles (IJs)/ml] on the silkworms, while they did little lethal effect (half lethal concentration of 150,000 IJs/ml) on the ants in topical assays. Both the nematodes and the bacteria did not give lethal effect to the albino rats, Rattus norvegicus, when they were fed orally into the rats. Also, any of these microbial agents were not detected in the internal organs of the treated rats.

• Microbiology and Biotechnology Letters
• /
• v.38 no.2
• /
• pp.117-123
• /
• 2010

BT toxin is produced by a soil bacterium Bacillus thuringiensis and has long been used as a biological insecticide without any competition. Recently, Photorhabdus, a symbiotic bacterium from entomopathogenic nematodes, family Heterorhabditae, has been researched and discussed as alternatives to B. thuringiensis. Photorhabdus, which lives in the gut of entomopathogenic nematodes, is a highly virulent pathogen of a wide range of insect larvae. When an insect is infected by the nematodes, the bacteria are released into the cadaver, and produce a number of insecticidal toxins. The biological role of the different Photorhabdus toxins in the infection process is still unclear. Photorhabdus toxin complex (Tc) is highly secreted gut-active toxin and has been characterized as a potent three-component (A, B and C) insecticidal protein complex. These components are necessary for full oral activity against insect larvae. The Photorhabdus PirAB binary toxins exhibit a potent injectable activity for Galleria mellonella larvae, and have oral toxicity against mosquitoes and caterpillar pest Plutella xylostella. Other toxin, 'makes caterpillars floppy' (Mcf) showed injectable activity on caterpillars. Recombinant Mcf triggers apoptosis in both insect hemocytes and the midgut epithelium and carries a BH3 domain. In this review, the relationship between the Photorhabdus and the nematode is discussed and recent important insecticidal toxins from Photorhabdus are described.

• Proceedings of the Korea Society of Environmental Biology Conference
• /
• 2003.11a
• /
• pp.81-85
• /
• 2003

In round numbers the 100 strains of entomopathogenic nematodes were isolated through the investigation of cultivated including the ginseng forming cultivated and forest soil samples by silkworm trap. The 28 strains of nematodes were selected among the isolated entomopathogenic nematodes that were confirmed the pathogenicity against Holotrichia morosa, Hoiotrichia diomphalia and Ectinus sericeus, the pest of korean ginseng and silkworm. Pathogenicity of the 2025, 2027, 2028, 2034, 2039 and 2057 strains was excellent. Selected entomopathogenic nematodes are classified of two species by morphologiacl and molecular studies, which were Sterinernma carpocapsae sp. and Diplogaster lethier sp.. Diagnostic characters include body length, lateral field pattern, tail shape and so on. The DNA sequences of the ITS region of rDNA shows similar to S. carpocapsae and .D. lethier. Isolated entomopathogenic nematodes were demonstrates that are quite within the realms of possibility for biological control agents of the pests of Korean Ginseng.

• Korean journal of applied entomology
• /
• v.46 no.1 s.145
• /
• pp.147-151
• /
• 2007

Laboratory tests were conducted to determine the susceptibility of the alfalfa weevil, Hypera postica to Korean entomopathogenic nematodes, Steinernema carpocapsae GSN1 strain (ScG), S. glaseri Dongrae strain (SgD), Heterorhabditis bacteriophora Hamyang strain (HbH), and Heterorhabditis sp. Gyeongsan strain (HeG) at the petri dish assay. The larval mortality of H. postica was significantly different depending on nematode species and treatment concentration. SgD and HeG strain were more effective against H. postica larva than ScG and HbH strain. When SgD and HeG strain were treated with the rate of >20 infective juveniles (ijs) per alfalfa weevil larva, mortality was ca. 77.5-100% at the late instars of H. postica in 3 days. The number of established nematode was significantly different depending on nematode species, whereas number of progeny was not significantly different. The mean number of established us of SgD strain in a host was the highest at 80 ijs by 30.2. The highest progeny number of HeG strain was 2,671.5 with 80 ijs. All nematode strains were not parasitic entirely to H. postica adults. These results show that alfalfa weevil late larva is highly susceptible to Korean entomopathogenic nematodes in the laboratory.

• The Korean Journal of Pesticide Science
• /
• v.20 no.4
• /
• pp.361-368
• /
• 2016

Japanese pine sawyer (JPS), Monochamus alternatus is a vector insect of pine wood nematode, Bersaphlenchus xylophilus in Korea and Japanese pine forest. This study was to evaluate the possibility of biological control of JPS with Korean entomopathogenic nematodes (EPNs). Korean EPNs (Heterorhabditis sp. Gyeongsan, Steinernema carpocapsae GSN1, S. glaseri Dongrae and S. longicaudum Nonsan strain) were infested bate insect, Galleria mellonella in log of dead pine tree. Result showed that, S. carpocapsae GSN1 strain has the highest pathogenicity. Heterorhabditis sp. Gyeongsan and S. carpocapsae GSN1 had infested bate insect, which located in 7.5 cm depth of pine log. EPN has pathogenicity against larva and adult of JPS. Spray application of EPNs against adult of JPS, Heterorhabditis sp. Gyeongsan strain showed higher pathogenicity than S. carpocapsae GSN1 strain. EPN infested larva of JPS was detected on bark spray treatment with S. carpocapsae GSN1 strain in dead pine log that naturally infested larva of JPS however, no EPN infested JPS was detected on soaking of pine log with suspension of S. carpocapsae GSN1 strain. Though EPN had found with low efficacy against JPS but still possible to apply to control the boring insect pest as they can control log dwelling insect.

• The Korean Journal of Pesticide Science
• /
• v.10 no.2
• /
• pp.107-116
• /
• 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 $ha^{-1}$.

• Korean Journal of Organic Agriculture
• /
• v.23 no.4
• /
• pp.797-811
• /
• 2015

This study was carried out to identify the control effect of entomopathogenic microagent against Spodoptera exigua on organic chinese cabbage. In laboratory condition, insecticidal activity of 4 commercial BT pesticides against S. exigua were lower than 10% against second instar S. exigua. The insecticidal activity of entomopathogenic nematode were 33.3%, 83.3% and 100% at the concentration of $1{\times}10^2$, $3{\times}10^2$, $1{\times}10^3nematodes/ml$, respectively. Mixture of BT and nematode showed growth inhibition against S. exigua larvae. S. exigua nucleopolyhedrovirus (SeNPV) of $10^5PIBs/ml$ showed more than 70% insecticial activity. The yield of SeNPV was increased as in higher initial inoculation concentration of NPV, food supply, and growth temperature increased. In greenhouse experiment, the control value of BT and nematode mixture treatment was higher than BT and nematode treatment alone against S. exigua. In treatment of $10^7PIBs/ml$ of SeNPV, S. exigua was controlled completely. In farm condition, mixture of microbial agent and organic agricultural material showed higher control value against lepidopteran pest including S. exigua than BT single treatment.

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

• Korean Journal of Environmental Biology
• /
• v.21 no.3
• /
• pp.271-275
• /
• 2003

The direct count and MPN (Most Probable Number) methods were used to measure the number of nematodes in soils collected from cultivated and non-cultivated fields. As a result, the number of nematodes from cultivated soils was higher than the non-cultivated soils (NC -1, NC -2). On the other hand, upon measuring the value from the organo farming cultivated soils (OC, OR) and conventional cultivated soils (CC, CR), the former showed 16 times higher than the latter. These results indicate that nematode population which can multiply in the organic compounds abundantly exist in the organo farming cultivated soil. Isolated entomopathogenie nematodes are composed of two orders, which were Rhabditida and Diplogasterida. To determine the pathogene-city of them using the 5th larvae and pupae silkworm, and the following mean $LD_{90}$ values were found: 24 to 30 hours in Rhabditida and 36 to 48 hours in Diplogasterida nematode, respectively. This study indicates that nematodes are sensitive to this kind of environmental disturbance. Isolated entomopathogenic nematodes were suggested that aye quite within the realms of possibility for biological control agents.

• Korean Journal of Organic Agriculture
• /
• v.30 no.1
• /
• pp.103-118
• /
• 2022

Photorhabdus is a bacterial symbiont of entomopathogenic nematodes of the genus Heterorhabditis in the family Heterorhabditidae. Photorhabdus is known to have nematicidal activity in addition to insecticidal activity. P. temperata isolated from Korean indigenous H. megidis Gwangju strain also produced high control efficacy against root-knot nematode Meloidogyne incognita and root-lesion nematode Pratylenchus penetrans. P. temperata has drawn interest as a potential bionematicide for the control of root-knot nematodes thereby. For the registration as an organic agricultural material, the toxicity of P. temperata was assessed by the acute toxicity test in carp (Cyprinus carpio) and acute oral and dermal toxicity tests in Sprague-Dawley rat (Rattus norvegicus) in compliance with the guidelines of the Rural Development Administration (RDA). In the acute toxicity test in fish, neither lethality nor abnormal responses of carp were observed. Body length and weight of carp and changes in DO concentrations and pH values were not significantly different between the treated group and the untreated control. In the acute oral and dermal toxicity tests, clinical signs, abnormal behavior, mortality, and pathological findings were not observed in all the experimental rats. The weight increment of all rats was normal. Acute toxicity results of P. temperata in fish and rats belonged to categories III, IV, and IV of RDA, respectively. Toxicity results of the present study indicated that P. temperata could be a safe and promising bionematicide against root-knot nematodes and root lesion nematode.