• Microbiology and Biotechnology Letters
• /
• v.18 no.3
• /
• pp.301-304
• /
• 1990

In the mosquitocidal delta-endotoxins from Bacillus thuringiensis subsp, isruelensis and B. thuringiensis subsp. darmstudiensis 73E10-2, were contained an immunologically homologous protein. The homologous protein was confirmed from Ouchterlony test, irnmuno-electrophoresis, and enzyme linked immunoassay by polyclonal antibodies against the delta-endotoxins of both strains.

• Korean journal of applied entomology
• /
• v.49 no.4
• /
• pp.417-422
• /
• 2010

Cultural characteristics Lecanicillium lecani Btab01 and its insecticidal activity against tobacco whitefly (Bemisia tabaci) were investigated. On potato dextrose agar, tryptic soy agar and SDA+Y media, mycelial growth of L. lecani Btab01 was best at $20{\sim}25^{\circ}C$ and suppressed above $28^{\circ}C$. Both solid culture and liquid culture of L. lecani Btab01 showed high insecticidal activity, 93.9 and 98.3% respectively, against nymph of tobacco whitefly, but there is no significant difference. When culture of L. lecani Btab01 was treated at the concentration of $10^5$, $10^6$, $10^7$ and $10^8$ cfu/ml, their insecticidal activity were 5.8%, 33.8%, 77.3% and 98.5% respectively, and $LT_{50}$ values were 16.1 days, 7.3 days, 5.1 days and 3.5 days respectively. When nymphs were treated by the cultures of L. lecani Btab01 and maintained under saturated condition for zero hour, 24 hours and 168 hours, their control activities were 0%, 20.3% and 100% respectively. Spore germination of L. lecani Btab01 was increased about two times by adding edible oil. When L. lecani Btab01 was treated to control nymph with 0.1% edible oil, it showed high control activity(98.6%) compared to single treatment of L. lecani Btab01 (79.9%).

• The Korean Journal of Ecology
• /
• v.22 no.5
• /
• pp.255-263
• /
• 1999

Entomopathogenic nematodes were isolated through the investigation of soil samples from various biotopes in south Korea, the efficiency of isolation for highly pathogenic nematodes to silkworms (Bombyx mori) was as high as 28 %. Twenty-eight strains of nematodes, selected among 100 samples by silkworms were confirmed the pathogenicity, multiplicity, and tolerance against various condition of preservation. Pathogenicity of the nematode isolates to agricultural and environmental pests such as Calliphora vomitoria, Pseufaletia separata, Palomena angulosa, and Melolontha incana were high. Mortality was varied from 20 to 100% by the pest insects and nematode strains. The high detectablity of entomopathogenic nematodes resulted from the methods of collection for soil samples within 10 cm depth after eliminating dried soil surface and the use of silkworm trap. High population of entomopathogenic nematodes represented the strong activity and broad action radius in the environment. Most of the nematode isolates were successfully cultured on the silkworm host as well as on artificial media, and proved their potential for the use of biological control agent.

• Korean Journal of Weed Science
• /
• v.6 no.1
• /
• pp.67-75
• /
• 1986

This study was undertaken to investigate the interrelation between herbicide and insecticide and fungicide on rice (Oryza saliva L.) at various growth stages. Carbamate insecticide BPMC (2-sec-butylphenylmethyl-carbamate) severely inhibited germination of rice when applied alone and in combination with herbicides tested. No germination inhibition was obtained with thio- and dithiocarbamate pesticides. Post-germination growth of rice was severely inhibited by the treatments which were combined with BPMC irrespective of herbicides studied. Phytotoxicity of pendimethalin (3,4-dimethyl-2,6-dinitro-N-1-ethyl propylamine) was reduced by antagonistic effect of organophosphorus compounds. When herbicides were applied with either insecticide or fungicide, post-germination growth of rice was more greatly affected by the concentration of herbicides than that of insecticides or fungicides. Most of herbicide-insecticide or herbicide-fungicide treatments did not cause great phytotoxicity on rice when applied 5 days after transplanting. Foliage activity of phenoxy herbicide 2,4-D (2,4-dichlorophenoxy acetic acid) and MCPA [(4-chloro-o-tolyl) oxy acetic acid] increased with addition of carbamate and urea pesticides.

• Korean journal of applied entomology
• /
• v.4
• /
• pp.47-50
• /
• 1965

Many of the chlorophenol derivatives are widely used as insecticides, herbicides and plant growth regulators. The function and use of these chemicals would be different according to the number of chlorine and their chemical structures. It was reported in this article that 1) Bis(trichlorophenoxy) ethane was synthesized with 2 mol-trichlorophenol and 1 moi-dibromoethane in 2 moi-Sodium hydroxide alcohol solution, and 3) the insecticidal activity of Bis(trichlorophenoxy) ethane was compared with Phenkapton, Tedion V-18, BHC, and DDT, on Citrus red mite, Bombix mori (Silk worm), and Daikon leaf beetle(Phaedon brassicae) 3) The toxicity of Bis(2, 4, 5-trichlorophenoxy) ethane and Bis(2, 4, 5-trichlorophenoxy) ethane was studied on mice. The following results were obtained. 1) Yield of Bis(2, 4, 5-trichlorophenoxy) ethane, $50.06\%$, m.p. $157-159^{\circ}C$, and yield of Bis(2,4, 6-trichlorophenoxy) ethane, $32.60\%$, m.p. $162-163^{\circ}C$. 2) Insecticidal activity of Bis(2, 4, 5-trichlorophenoxy) ethane to Citrus red mite is stronger than that of Tedion V-18, and weaker than that of Phenkapton. 3) Insecticidal activity of Bis(2, 4, 5-trichlorophenoxy) ethane to Bombix mori is weaker than those of BHC and DDT. 4) Insecticidal activity of Bis(2. 4, 5-trichlorophenoxy) ethane to Daikon leaf beetle proved to be ineffective. 5) Five rams of Bis(2, 4, 5-trichlorophenoxy) ethane and Bis(2, 4, 6-trichlorophenoxy) ethane pet kg of body weight respectively were given to mice orally, and none of the mouse was killed by it after a period of 72 hours. Therefore it seems that there is almost no toxicity.

• Korean journal of applied entomology
• /
• v.53 no.4
• /
• pp.409-413
• /
• 2014

This study was conducted to observe the effects of dried tobacco leaf smoke on controlling aphids in a laboratory and a greenhouse. Insecticidal activity of tobacco smoke against Aulacorthum solani in an acrylic cage was higher when a burley cultivar, rather a flue-cured cultivar, was used. Mortality of A. solani, Aphis gossypii, and Myzus persicae was 63.9%, 94.4%, and 97.2%, respectively, after 50mg of tobacco smoke on their host plants in an acrylic cage. Mortality of M. persicae after tobacco smoke was used was higher in eggplant than in Chinese cabbage. When 100 g and 200 g of flue-cured tobacco were smoked in a $100m^2$ greenhouse for 2 h, the control values against A. solani were 28.9% and 95.4%, respectively; the control value after 14 h of smoking was more than twice the value after 2 h of smoking. The control value against A. gossypii was more than 80% after tobacco smoke was used in a greenhouse in an organic cucumber farm. Tobacco smoke can be an effective control against aphid pests in greenhouses if an appropriate amount of tobacco and smoking time on the basis of the greenhouse conditions are used.

• The Korean Journal of Pesticide Science
• /
• v.12 no.2
• /
• pp.184-191
• /
• 2008

Entomopathogenic bacteria (Xenorhabdus nematophila, X. sp. and Photorhabdus temperata subsp. temperata) isolated from entomopathogenic nematodes express potent insecticidal activity in insect hemocoel. They are also known to suppress insect immune mediation by inhibiting phospholipase $A_2$, leading to host immunosuppression. This study analyzed effects of their cultured broths on inhibiting insect immunosuppression. For this, we removed all bacterial cells using $0.2\;{\mu}m$ pore sized membrane from the bacteria-cultured broth. All three sterilized cultured media, in dose-dependent manners, significantly inhibited hemocyte-spreading behavior of 5th instar larvae of Spodoptera exigua. However, they showed differential inhibitory activities among different bacterial species, in which X. nematophila showed the most potent inhibitory activity. This immunosuppressive effect was applied to increase the pathogenicity of Bacillus thuringiensis (Bt). All three bacterial cultured broths including bacterial cells significantly potentiated Bt pathogenicity against young S. exigua larvae when each of them was orally administered in a mixture of low dose of Bt. Finally, we tested the effect of oral administration of the cultured media containing the immunosuppressive compound(s) secreted by the bacteria. The membrane-sterilized cultured broths were mixed with the low dose of Bt and then orally administered to the young S. exigua. Only the cultured medium of X. nematophila showed increase of Bt pathogenicity. These results indicated that the; cultured media of the three bacteria possessed immunosuppressive factor(s), which may act to potentiate Bt toxicity to young S. exigua larvae.

• The Korean Journal of Pesticide Science
• /
• v.19 no.3
• /
• pp.279-286
• /
• 2015

Cotesia plutellae bracovirus (CpBV) is a polydnavirus symbiotic to C. plutellae parasitizing young larvae of the diamondback moth, Plutella xylostella. Several CpBV genes play important roles in suppressing immune responses of the parasitized larvae. This study tested a hypothesis that the CpBV genes inducing host immunosuppression could be applied to develop a potent recombinant baculovirus. Based on a previous study, a recombinant baculovirus expressing CpBV-ELP1 (AcMNPV-ELP1) was selected and multiplied using larvae of the beet armyworm, Spodoptera exigua. The recombinant viruses were produced in a yield of $5{\times}10^{10}$ polyhedral inclusion body (PIB)/larva. The cultured AcMNPV-ELP1 exhibited a much higher pathogenicity against S. exigua larvae. However, its insecticidal activity was varied among larval instars of S. exigua, in which first and late instars were high susceptible. Spray of the recombinant baculovirus ($5{\times}10^6PIB/mL$) exhibited higher control efficacy (${\approx}$ 88%) against S. exigua larvae infesting cabbage than a chemical insecticide, tebufenozide, at 7 days after treatment. These results indicate that AcMNPV-ELP1 mass-cultured using host insect system is highly pathogenic and can be applied to develop a novel microbial control agent.

• Korean journal of applied entomology
• /
• v.56 no.1
• /
• pp.19-28
• /
• 2017

Polydnaviruses (PDVs) are a group of double-stranded DNA viruses symbiotic to some endoparasitoid wasps. Cotesia plutellae bracovirus (CpBV) is a PDV symbiotic to an endoparasitoid wasp, C. plutellae, parasitizing young larvae of Plutella xylostella. An early expressed gene, CpBV-ELP1, plays an important role in the parasitism by suppressing host cellular immunity by its cytotoxic activity against hemocytes. This study aimed to test its oral toxicity against insect pest by expressing it in a recombinant tobacco plant. A recombinant CpBV-ELP1 protein was produced using a baculovirus expression system and secreted to cell culture medium. The cell cultured media were used to purify CpBV-ELP1 by a sequential array of purification steps: ammonium sulfate fractionation, size exclusion chromatography, and ion exchange chromatography. Purified rCpBV-ELP1 exhibited a significant cytotoxicity against Spodoptera exigua hemocytes. CpBV-ELP1 was highly toxic to the fifth instar larvae of S. exigua by injection to hemocoel. It also showed a significant oral toxicity to fifth instar larvae of S. exigua by a leaf-dipping assay. CpBV-ELP1 was cloned into pBI121 vector under CaMV 35S promoter with opaline synthase terminator. Resulting recombinant vector (pBI121-ELP1) was used to transform Agrobacterium tumefaciens LBA4404. The recombinant bacteria were then used to induce callus of a tobacco (Nicotiana tabacum Xanthi) leaves and subsequent generation (T1) plants were selected. T1 generation tobacco plants expressing CpBV-ELP1 gave significant insecticidal activities against S. exigua larvae. These results suggest that CpBV-ELP1 gene can be used to control insect pests by constructing transgenic crops.

• Korean Journal of Environmental Biology
• /
• v.17 no.3
• /
• pp.321-330
• /
• 1999

Nematodes were isolated using silkwom trap through the investigation of 100 soil samples from various biotopes in Korea. The 30 nematode strains from soil and dead insects by the pathogenicity aganinst silkworms (Bombyx mori mori) and insect pests of Calliphora vomitoria, Pseufazetia separata, Palomena angulosa, and Melolontha incana. Mortailty of the silkworm larvae and pupae were as high as 100% by nematode infection, those of insect of pests were varied from 20 to 100%. The 30 strains of entemopathogenic nematodes were classified into five groups of Rhabditidae, Diplogatroidae, Heterorhabitidae, Steinernematidae, and Tylenchida by morphological criteria. The genetic relationships among the 30 nematode strains were analyzed by various RAPD bands with twenty primers. The 30 nematode strains were classified into six major subgroups on the basis of the genetic similarity coefficient of 0.853. The grouping by RAPD was agree with those of morphological taxa in discrimination of the higher group, however, was not completely agree in the subgroup. The family Steinernematidae belong to Rhabditida was clarified as closer to the Tylenchida, rather than the other Rhabditida of Heterorhabitidae, Rhabditidae, and Diplogatroidae in genetic distance valule. From the result of the morphological classification and RAPD of the genomic DNA showed that genetic relationship analysis furnish infurmation on phylogenetic classification and relationships of entomopathogenic nematodes. The application of genetic similarity will overcome the limitation of taxonomy and classification of morphologically simple nematode. Several primers were confirmed those utility of identification for individual nematode strains, the methods of molecular genetics secured the simplicity, rapidity and accuracy on the selection of entomopathogenic nematodes.