• Journal of the Korean Society for Marine Environment & Energy
• /
• v.8 no.1
• /
• pp.9-16
• /
• 2005

A series of experiments was conducted to evaluate the effects of temperature on the survival, growth and sensitivity of the benthic amphipods, Mandibuluphoxus mai and Monocnrophium acherusicum, which have been recently developed as new sediment toxicity testing species in Korea. The biological performance for each amphipod species was determined by the survival and growth rates at different water temperatures. The influence of temperature on the sensitivity to reference toxicant, Cd, was determined by the comparison of survival rates of amphipods exposed to control and Cd-spiked seawater at different temperatures. Temperature significantly influenced on the survival, growth and Cd sensitivity of both amphipods. Tolerable ranges of temperature for the >80％ individuals of both M. mai and M. acherusicum with sediment substrates were mostly overlapped (13 to 22℃). The daily growth rates of M. mai and M. acherkisicum increased proportionally with temperature up to 20℃ and 25℃. respectively. Similarly, the sensitivities of M. mai and M. acheyusicum to Cd increased with temperature up to 20℃ and 15℃, respectively. Overall results showed that temperature is a substantially important factor potentially influencing the results of lethal and sublethal bioassays using the amphipods. Therefore, defining the adequate ranges of experimental temperature for the toxicity testing species is the pre-requisite for the development of standardized bioassay protocols.

• Korean Journal of Environmental Biology
• /
• v.35 no.4
• /
• pp.557-565
• /
• 2017

For our survey of insecticidal resistance of Palm thrips (Thrips palmi Karny), we established the discriminating time (DT) and concentration (DC) of nine insecticides, and we conducted a bioassay about seven local populations via leaf-dipping methods. The discriminating times of the recommended concentration (RC) were 24 h at emamectin benzoate EC and spinetoram SC, 48 h at chlorfenapyr EC, 72 h at spinosad SC, cyantraniliprole EC, acetamiprid WP, dinotefuran WG, imidacloprid WP and thiacloprid SC after treatment. The DC estimated the concentration which showed the difference within the mortalities of these local populations. The DCs were emamectin benzoate EC $0.013mg\;L^{-1}$ (RC, $10.8mg\;L^{-1}$), spinetoram SC $0.125mg\;L^{-1}$ (RC, $25.0mg\;L^{-1}$), chlorfenapyr EC $0.25mg\;L^{-1}$ (RC, $50.0mg\;L^{-1}$), spinosad SC $0.083mg\;L^{-1}$ (RC, $50.0mg\;L^{-1}$) and cyantraniliprole EC $5.0mg\;L^{-1}$ (RC, $50.0mg\;L^{-1}$), and DCs of neonicotinoids were their RCs, that is, acetamiprid WP (RC, $40.0mg\;L^{-1}$), dinotefuran WG (RC, $20.0mg\;L^{-1}$), imidacloprid WP(RC, $50.0mg\;L^{-1}$) and thiacloprid SC (RC, $50.0mg\;L^{-1}$). From our investigation into the resistance of the local populations with DT and DC application, the neonicotinoid insecticides have shown a high resistant level for all the local populations, and the other insecticides have demonstrated low or non-resistance. In the use of neonicotinoid insecticides to control Palm thrips, one must take caution. As a result, the establishment of DT and DC in the single dose bioassay method was helpful for surveying the insecticide response dynamics and the development of an insecticide resistance management strategy.

• Applied Biological Chemistry
• /
• v.41 no.2
• /
• pp.191-196
• /
• 1998

The MeOH extract from root of Pulsatilla koreana was showed antimicrobial activities against bacteria and yeast. The antimicrobial active substances of MeOH extract were successfully purified with solvent fractionation, silica gel adsorption column chromatography and Sephadex LH-20 column chromatography. The purified two active substances were isolated by HPLC and identified as 4-hydroxy-3-methoxycinnamic acid and 3,4-dihydroxycinnamic acid by MS, $^{1}H-NMR$ and $^{13}C-NMR$.

• Clean Technology
• /
• v.23 no.1
• /
• pp.27-33
• /
• 2017

In this study, toxicities of seven metals (Cu, Cd, Cr, As(III), As(V), Zn, Ni) and five metal oxide nanoparticles (NPs: CuO, ZnO, NiO, $TiO_2$, $Fe_2O_3$) were evaluated based on the growth of Chlorella vulgaris. Effect on algae growth was evaluated by integrating the results of absorption, chlorophyll content, and cell count. The toxicity rankings of metals was observed as Cr ($0.7mgL^{-1}$) > Cu ($1.7mgL^{-1}$) > Cd ($3.2mgL^{-1}$) > Zn ($3.9mgL^{-1}$) > Ni ($13.2mgL^{-1}$) > As(III) ($17.8mgL^{-1}$) ${\gg}$ As(V) (> $1000mgL^{-1}$). Slightly different orders and sensitivities of metal toxicity were examined depending on endpoints of algal growth. In case of NPs, regardless of endpoints, similar toxicity rankings of NPs ($TEC_{50}$) were observed, showing ZnO ($2.4mgL^{-1}$) > NiO ($21.1mgL^{-1}$) > CuO ($36.6mgL^{-1}$) > $TiO_2$ ($62.5mgL^{-1}$) > $Fe_2O_3$ ($82.7mgL^{-1}$). These results indicate that an integrating results of endpoints might be an effective strategy for the assessment of contaminants.

• The Korean Journal of Pesticide Science
• /
• v.15 no.2
• /
• pp.194-200
• /
• 2011

Diamondback moth (DBM, Plutella xylostella L.) is known as the most destructive pest of cruciferous crops worldwide. As most insecticides targeted to mainly larval stage, new insecticides which have hatching-inhibitory or ovicidal activity could be more efficient to control DBM. Therefore, we developed an easy and efficient method for screening ovicidal activity of DBM eggs using aluminum foil. The aluminum foil ($4{\times}12$ cm) coated with filtered juice of chinese cabbage leave (hereinafter called oviposition foil) exposed to 300 newly-emerged adults for 24 hours inside the rearing container. The oviposition foils were replaced every 4 days consecutively after mating, but it was better to discarded over then. Oviposition foil were divided into 6 to 12 pieces depending on egg mass volume. After dipping into test solutions for 10 seconds using faucet, oviposition foil pieces were placed into common petri dish, and then investigated hatchability. The effect of methanol solvent (50%) for 10 seconds dipping on the toxicity against DBM eggs was negligible. In addition, whether covering the petri dish or not should be dependent on nature of active compounds tested. With applying the new bioassay method, methanol extracts from 50 plants were tested the ovicidal activity to DBM eggs. Among them, four plant extracts; Angelica tenuissima root, Lycium chinense root, Cnidium officinale root and Polygala tenuifolia root, showed high ovicidal activity of over 90% control efficacy, against DBM eggs.

• Applied Biological Chemistry
• /
• v.30 no.1
• /
• pp.54-59
• /
• 1987

Occurrence of two type brassinosteroid-like substances and less molecular weight substance than brassinosteroid were suggested in immature Vicia faba seeds extracts, which were purified using various chromatographic techniques, by Korean rice-lamina inclination test.

• The Korean Journal of Mycology
• /
• v.43 no.3
• /
• pp.180-184
• /
• 2015

For selection of effective antagonists for control Sclerotinia rot of lettuce, 29 bacteria were isolated from soil in Korea. The bacterial isolates M27 and RM43 identified as Bacillus sp, were selected as prospective agents for inhibiting mycelial growth of Sclerotinia sclerotiorum and Sclerotinia minor. Among the selected isolates, Bacillus amyloliquefaciens M27 effectively suppressed incidence of Sclerotinia rot by Sclerotinia sclerotiorum and Sclerotinia minor in the lettuce nursery.

• Journal of Life Science
• /
• v.31 no.7
• /
• pp.609-616
• /
• 2021

Bacterial soft rot, caused by Pectobacterium carotovorum subsp. carotovorum (Pcc), is one of the destructive diseases of radish (Raphanus sativus) in Asian countries. The objective of this study was to establish an efficient bioassay method for the evaluation of bacterial soft rot resistance in commercial radish cultivars. First, an efficient bioassay method for examining resistance to bacterial soft rot in commercial radish cultivars was investigated. Six commercial radish cultivars were tested under various conditions: two temperatures (25℃ and 30℃), three inoculations methods (drenching, spraying, and root dipping), and two growth stages (two- and four-leaf stages). The results suggested that spraying with 1×10⁶ cfu/ml of bacterial inoculums during the four-leaf stage and incubating at 30℃ could be the most efficient screening method for bacterial soft rot resistance in commercial radish cultivars. Second, we investigated the degree of resistance of 41 commercial radish cultivars to five Pcc isolates, namely KACC 10225, KACC 10343, KACC 10421, KACC 10458, and KACC 13953. KACC 10421 had the strongest susceptibility in terms of moderately resistant disease response to bacterial soft rot. Out of the 41 radish cultivars, 13 were moderately resistant to this pathogen, whereas 28 were susceptible. The moderately resistant radish cultivars in this investigation could serve as resistance donors in the breeding of soft rot resistance or could be used to determine varietal improvement for direct use by breeders, scientists, farmers, researchers, and end customers.

• 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.

• Research in Plant Disease
• /
• v.24 no.1
• /
• pp.41-51
• /
• 2018

Since fire blight disease on apple and pear was produced in Korea in 2015, there were no registered chemicals to control against this disease. Instead, several antibacterial chemicals that were registered for other bacterial diseases such as soft rot and bacterial spot have been authorized by Rural Development Administration (RDA). However, these chemicals are not tested efficacy for fire blight disease except damage by those treatments on apple and pear in Korea. Thus, we evaluated efficiency using in vitro and in planta assays of antibacterial chemicals such as antibiotics and copper compounds including kasugamycin, oxytetracycline, oxolinic acid and streptomycin, and copper hydroxide, copper sulfate, oxine copper and tribasic copper sulfate, respectively. We also tested two kinds of biological agents. As expected, significant antibacterial effect was observed in vitro test of both antibiotics and copper-based chemicals. In planta test based on disease severity including ooze and water-soaked formation on immature pears, bacterial populations on blooms, and blight lesion formation in artificially inoculated shoots, kasugamycin, oxytetracycline and streptomycin have been shown the most efficiency among tested antibiotics. Four copper-based chemicals tested in this study, control effects are little bit lower than agricultural antibiotics but they seem to be available to use in terms of winter season. Biocontrol agents were also shown possibility to treat in eco-friendly farms. In addition, there are no antibiotic resistance genes in Korean isolates against antibiotics, which were selected for suppression of fire blight in this study.