• The Korean Journal of Pesticide Science
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• v.4 no.2
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• pp.56-62
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• 2000

Effects of sublethal dose of imidacloprid on biological characteristics, such as longevity, fecundity and excretions from brown planthopper (BPH) and its repellency to imidacloprid were examined. Topical application of imidacloprid to BPH at the dose of $LD_{10}$ and $LD_{30}$ (These values were determined at 48 hours after topical application of imidacloprid) was remarkably increased the mortality from 3 days after application and showed over 90% mortality on 4 days after application. Topical application of imidacloprid at dose of $LD_{10}$ (16 days) showed no difference compared to the control (16.9 days) in the longevity, while application of $LD_{30}$ was reduced the longevity of BPH to 13.5 days. Application of sublethal dose of imidacloprid to BPH adults reduced the number of eggs laid per day and for adult stage, and the hatchability of their eggs. By root zone application at the dose of $LC_{30}$, 50% longevity and 40% fecundity was reduced respectively, but showed no effect on number of eggs laid per day. The day on which BPH laid 50 % of eggs in number were 7.6 days at the $LC_{10}$ and 5.9 days the of $LC_{30}$ respectively. Hatchabilities of the groups treated with imidacloprid were lower than that of the control. Topical application to BPH at the dose of $LD_{10}$ did not reduce the amount of excretes, but application at the dose of $LD_{30}$ was reduced 26.5% of excretion compared to the control. Leaf dipping into the solution of concentration of $LC_{10}$ and $LC_{30}$ was reduced 96.4% and 98.0% of excretion, respectively. And root zone treatment at the concentration of $LC_{10}$ and $LC_{30}$ reduced 79.5% and 96.6% of excretion, respectively. Repellency rates of BPH to imidacloprid were 20% regardless of the dose of application.

• Journal of Environmental Health Sciences
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• v.15 no.2
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• pp.97-106
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• 1989

This experiment was performed to study the acute toxic effects of mereuric chloride(HgCl$_{2}$) in goldfish (Carassius aurams). In the study, Lc$_{50}$ values were determined for each 24, 48, 72 ,and 96-hr and mercury bioassay during the tests were performed. in five parts gill, kidney, liver, muscle and egg. The results isummarized were as follows 1. In the range of acute lethal toxicity for goldfish was 0.15-1.50 mg/l and the Lc$_{50}$ values decreased with exposure time. 2. The Lc$_{50}$ values of HgCl$_{2}$ for goldfish at 24, 48, 72 and 96 hour were 0.64, 0.53, 0.46, and 0.39 mg/l, respectively. 3. In the 400 $\mu$g/l treatment group, the average levels of mercury residues in the gill, kidey, liver, muscle and egg during 96 hour were 107.02 $\mu$g/g, 8.65 $\mu$g/g, 6.87 $\mu$g/g, 0.61 $\mu$g/g, and 0.82 $\mu$g/g, respectively. 4. The mercuny residues of gill was up to 12-175 times greater than mercury contents found in the other tissues.

• The Journal of Natural Sciences
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• v.11 no.1
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• pp.85-88
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• 1999

This study was carried out to determine the lethal water temperature and lethal concentrations of phnol and lead on Anodonta woodiana collected from Bam islet in Han river, Seoul, Korea. Lethal temperature$(LT_{48,50})$ on a woodiana was $37-38^{\circ}C$, and lethal concentrations$(LC_{50})$ of phenol and lead nitate were 1200 ppm and 220 ppm, respectively.

• Journal of Aquaculture
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• v.11 no.4
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• pp.429-435
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• 1998

This study compared acute ammonia toxicity in juvenile rockfish and red sea bream. Oxygen concentration affected ammonia toxicity to aquatic animals. Without aeration, the 96-hr $LC_50$ values of $NH_4^+$and un-ionhized ammonia for juvenil rockfish(3.6g, 6.6cm) were 2.61 and 0.09 mg/l, respectively. The 3-hr $LC_50$ values of $NH_4^+$ for the size of 1.9g (5.2cm) and 3.6g (6.6cm) rockfish, and 1.0g (3.8cm) and 2.0g (5.0cm) red sea bream without aeration were 3.96, 3.94, 4.35 and 3.75 mg/l, respectively. When oxygen level was low, larger fish were more susceptible to ammonia toxicity than smaller one because of stress resulted from low oxygen. However, with aeration, the 96-hr $LC_50$ values of $NH_4^+$ for the size of 1.2g (3.9cm) and 2.3g (5.1cm) red sea bream with aeration were 3.84 and 3.90mg/l, respectively. The 6-hr $LC_50$values of $NH_4^+$ for the size of 3.1g (5.9cm) and 6.2g (7.0cm) rockfish with aeration were 3.83 and 3.94 mg/l, respectively. When oxygen level was high, larger rockfish and red sea bream were less susceptible to ammonia toxicity than smaller ones. The 6 hr-or 96 hr-$LC_50$ values of $NH_4^+$for rockfish with reduced ammonia toxicity. In comparing 96 hr-$LC_50$ values of $NH_4^+$ and un-ionized ammonia for juvenil rockfish with those for juvenil red sea bream, the values for rockfish were lower than for red sea bream. This indicates that juvenile rockfish is more susceptible to ammonia toxicity than juvenile red sea bream.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.3
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• pp.488-495
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• 1997

The effects of ammonia on survival and growth of the flounder larva, Paralichthys olivaceus, were examined by a static renewal bioassay method. The $96\;hr-LC_{50}$ with the developmental stages during the period from 1day to 23 day-old larvae ranged 0.273 to 1.023 mg $NH_3/\ell$. Tolerance of the larvae to ammonia toxicity was much sensitive at the early larval stage, and increased with the growth of the larvae. Threshold $96hr-LC_{50}$ in 1, 3 and S day-old larvae after hatching were 0.293, 0.248 and 0.379 mg $NH_3/\ell$, respectively. Survival rate and growth in body weight and body weight of the larva were reduced with increase of ammonia concentration in the range of 0.055 and 0.341 mg $NH_3/\ell$. The no-observable-effect concentration (NOEC) and lowest-observable- effect concentration (LOEC) of the flounder larve were 0.102 and 0.174 mg $NH_3/\ell$ for body length, and 0.151 and 0.198 mg $NH_3/\ell$ for body weight, respectively. Chronic value (ChV), which is the geometric mean of the NOEC and $NH_3/\ell$ to body length of the larvae were 0.124 mg $NH_3/\ell$. The coefficient of variation (CV) for body length was higher at high concentration than at low concentration.

• Journal of Aquaculture
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• v.15 no.2
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• pp.119-121
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• 2002

A study on the acute toxicity in the Nile tilapia, Oreochromis niloticus fry showed that the 24hr-$LC_{50}$ was 18.6% for NaCl,152 ppm for formaline and 2.1 ppm for $KMnO_4$. The fry responded to narrow range of concentration of all the tested chemicals and their toxic effects were dose-dependent.

• The Korean Journal of Pesticide Science
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• v.3 no.2
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• pp.74-80
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• 1999

These studies were carried out to investigate the effects of nonsteroidal ecdysone agonist, tebufenozide on embryonic and postembryonic development of sycamore lace bug, Corythucha ciliata. Tebufenozide exhibited ovicidal activity($LC_{50}=4.0$ ppm). Susceptibility of each instar nymphs to tebufenozide was nearly same($LC_{50}=2.3{\sim}6.0$ ppm). The tebufenozide treatment in the final instar affected the emergence, longevity and fecundity of surving adults significantly. Tebufenozide applied at high concentration (10 ppm) to younger adults delayed prioviposition period, and decreased adult longevity, the number of eggs laid per female and hatchability. The treatment also inhibited the ovarian development of the female adults.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.6
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• pp.530-535
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• 2012

Polycyclic aromatic hydrocarbons (PAHs) such as naphthalene, are released into the aquatic environment and have been identified as endocrine effects on marine organisms. Naphthalene makes up the highest fraction of PAHs in oil and shows the strong toxicity to aquatic organisms. I analyzed 24h-median lethal concentration (24h-$LC_{50}$) for juvenile olive flounder Paralichthys olivaceus to study the acute toxicity of naphthalene. Bioconcentrations in the gill, liver, kidney and muscle of olive flounder were analyzed after to 6 naphthalene concentrations of 0, 1000, 1800, 3200, 5600 and 10000 ${\mu}g/L$. Olive flounder has 24h-$LC_{50}$ value of 2410.76 ${\mu}g/L$ in Large group, and 2230.67 ${\mu}g/L$ in Samll group. Naphthalene concentration was varied with tissues. The concentrations of naphthalene were much higher in liver and kidney than in gill and muscle.

• Journal of fish pathology
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• v.19 no.3
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• pp.277-284
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• 2006

Application of wood vinegar in fish farms has been used for the disinfection of pathogenic microorganisms and the treatment of infectious diseases. This study was performed to know the acute toxicity of wood vinegar to carp Cyprinus carpio, flounder Paralichyhus olivaceus, rock fish Sebastes schlegeli and black sea bream Pagrus major. The 24 hr, 48 hr and 96 hr LC50 respectively were: carp 1243, 1143 and 1016 ppm; flounder 1397, 1253 and 1226 ppm; rock fish 1058, 993 and 967 ppm; and black sea bream 650, 616 and 596 ppm. Death and survival of fish exposed to lethal concentrations of wood vinegar were apparently related to massive necrosis, fusion and epithelial lifting of gill lamellar epithelium, suggesting the osmotic imbalance and lack of oxygen uptake.

• Korean Journal of Ecology and Environment
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• v.39 no.4 s.118
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• pp.419-423
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• 2006

In this study, acute toxicity of four pesticides (diazinon, iprodione, fenproparthrin, and myclobutanil) to Chinese bleak, Aphyocypris chinensis, and to study their adverse effects were conducted in static systems. The 96-hr $LC_{50}$ values were determined, as well as 95% confidence limits. The 96-hr $LC_{50}$ values of these chemicals derived for Chinese bleak were rank ordered from the most toxic to the least toxic technicals as follows: Fenproparthrin (0.003 mg $L^{-1}$)>Myclobutanil (9.1 mg $L^{-1}$)>Diazinon (14.1 mg $L^{-1}$)>Iprodione (31.8 mg $L^{-1}$), The data presented in this study indicate the acute toxicity tests carried out on only one fish species may lead to erroneous determination of water quality criteria and classification of test chemicals for environmental management and regulatory purpose. Therefore, more studies comparing the susceptibility of a variety of fish species to various toxicants are needed.