• 한국발생생물학회:학술대회논문집
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• 한국발생생물학회 2003년도 제3회 국제심포지움 및 학술대회
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• pp.72-72
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• 2003

The present study examined the possibility of cryopreservation of the D-shaped and umbo larvae of arkshell (Scapharca broughtonii), in terms of the survival rates after freezing and thawing. D-shaped and umbo larvae of arkshells were obtained from a shellfish farming on Yosu city. The average shell lengths were $93.3 \pm 10.1 \mu$m and $201.7 \pm 13.5 \mu$, respectively. Five cryoprotectants (CPAs), dimethyl sulfoxide (DMSO), glycerol, ethylene glycol (EG), propylene glycol (PG), and methanol, were tested at the concentrations of 1.5, 2.0 and 2.5 M. After larvae suspended in CPAs, cryoprotectants were loaded in 0.5 ml straws at a larval density of 50-100 larvae per straw, and epuilibrated for 10 and 20 minute at room temperature ($23^{\circ}C$), repectively. Straws were cooled at a rate of $1^{\circ}C$/min from $0^{\circ}C$ to $-12^{\circ}C$, held for 5 min at $-12^{\circ}C$, and then cooled at $2^{\circ}C$/min to $-35^{\circ}C$ and equilibrated for 5 min followed by plunging in liquid nitrogen. After storage in liquid nitrogen for 1 day, straws were thawed in a $30^{\circ}C$ water. As soon as straws were observed to melt, larvae were diluted with an equal volume of ASW and then washed twice with a large volume of ASW at an interval of 2 min to unload the CPAs. The results showed that after equilibration for 10 and 20 minute at room temperature, no larvae survived using methanol as CPAs, and it was observed that larval shells all open slightly, and larval flesh broke down and slopped over the shells. The highest survival rates (D-shaped larvae: 77.6%, umbo larvae: 59.3%) were obtained with 2M DMSO, and 1.5M glycerol yielded survival rates of 53.8% for D-shaped larvae and 37.5% for umbo larvae. The surviving D-shaped larvae showed active rotary motion and perfect membrane integrity and cytoplasmic normality, and the vigorous movement of veliger cilia was observed inside the closed shells. The breakdown of tissue occurred in the abnormal larvae, and the isolated cell often run out of shells.

• Journal of Microbiology and Biotechnology
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• 제26권10호
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• pp.1774-1780
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• 2016

Vegetative insecticidal proteins (Vips) are insecticidal proteins synthesized by Bacillus thuringiensis during the vegetative stage of growth. In this study, Vip3Aa protein, obtained by in vitro expression of the vip3Aa gene from B. thuringiensis WB5, displayed high insecticidal activity against Spodoptera litura aside from Spodoptera exigua and Helicoverpa armigera. Bioassay results showed that the toxicity of Vip3Aa protein against S. litura larvae statistically decreased along with the increase of the age of the larvae, with LC₅₀ = 2.609 ng/cm² for neonatal larvae, LC₅₀ = 28.778 ng/cm² for first instar larvae, LC₅₀ = 70.460 ng/cm² for second instar larvae, and LC₅₀ = 200.627 ng/cm² for third instar larvae. The accumulative mortality of 100% larvae appeared at 72 h for all instars of S. litura larvae, when feeding respectively with 83.22, 213.04, 341.40, and 613.20 ng/cm² of Vip3Aa toxin to the neonatal and first to third instar larvae. The histopathological effects of Vip3Aa toxin on the midgut epithelial cells of S. litura larvae was also investigated. The TEM observations showed wide damage of the epithelial cell in the midgut of S. litura larvae fed with Vip3Aa toxin.

• 한국패류학회지
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• 제19권1호
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• pp.25-32
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• 2003

To know the effects of the red tide and toxic dinoflagellates on survival and growth of larvae of the mussel, Mytilus galloprovincialis, laboratory experiments were conducted by incubating larvae with either unialgal culture of 4 dinoflagellate species (Amphidinium carterae, Prorocentrum triestinum, Gymnodinium impudicum, or Akashiwo sanguinea) or a standard food (Isochrysis galbana) for 10 days. The survival of larvae was higher than 80% when the food was A. carterae, G. impudicum, or A. sanguinea. The lowest survival (20%) was found when the food was P. triestinum. When the food was P. triestinum, the survival of larvae rapidly decreased from 87% at day 4 down to ca. 50% at day 6, and 20% at day 10. This implies that the larval population of M. galloprovincialis can seriously be affected if they are exposed to the red tide water dominated by P. triestinum for more than 4 days. Shell length of larvae either increased or decreased according to the food species. When the food was A. carterae, G. impudicum, or A. sanguinea, shell length of larvae increased. But, it decreased when the food was P. triestinum. Though shell length increased in 3 treatments, the daily increments (0.63 $\mu$ m for A. carterae, 0.46 m for $\mu$ G. impudicum, and 1.10 m for $\mu$ A. sanguinea) were smaller than that of the standard food (3.79 m for $\mu$ I. galbana). Correlation analyses chowed that the change in shell length was not significant when the food was A. carterae or G. impudicum. Therefore, all of 4 dinoflagellates affected the growth of M. galloprovincialis larvae: growth was negative for P. triestinum, nil for A. carterae and G. impudicum, and positive but lower than standard food for A. sanguinea. These imply that the dinoflagellates are less valuable as foods for M. galloprovincialis larvae. So, decreased growth rate of larvae is expected during red tides, which will consequently cause delayed metamorphosis or failure to recruitment to the adult populations. In considering the harmful effects of red tides on the aquatic ecosystem, not only the effects on adult populations of fish and shellfish, but also the effects on larval populations should be included.

• Animal cells and systems
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• 제8권4호
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• pp.313-317
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• 2004

A study was conducted to determine growth and survival rates of snakehead (Channa striata) larvae. Live foods such as Artemia salina nauplii, Moina micrura and bloodworm and artificial diet were given to larvae from 1-15 days after hatching as the 1st phase and from 15-30 days as the 2nd phase. In the 1st phase, the growth and survival rates of larvae fed with Artemia nauplii were significantly different from larvae fed with Moina (p < 0.05) with values of 28.5 mg, 49% and 26.7 mg, 31%, respectively. Meanwhile, all larvae fed with bloodworm (Chironomus sp.) or artificial diet (49% protein) died within 10 days of experiment. For the 2nd phase, growth of the fry fed with Artemia or Moina differed significantly from that fed with bloodworm or pellet (200.1, 187.7, 109.6 and 8.2 mg, respectively). Specific growth rate (SGR) of larvae fed with Moina was higher than that of larvae fed with Artemia (17.9 and 17.4% day$^{-1}$, respectively) in the 1st phase. In the 2nd phase, SGRs of larvae fed with Artemia (12.7% day$^{-1}$) or Moina (11.5% day$^{-1}$) were significantly higher than those of larvae fed with bloodworm (8.3% day$^{-1}$) or dry diet (6.1% day$^{-1}$). Generally, Artemia and Moina were suitable food for snakehead larvae during the first month of their life, and artificial diet was much less acceptable and resulted in poor growth and survival.

• Animal cells and systems
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• 제14권2호
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• pp.125-128
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• 2010

This study investigated the effect of different light intensities on first feeding of chub mackerel Scomber japonicus larvae. Fertilized eggs, obtained from LHRHa-induced spawning of captive broodstock, were stocked (60 larvae/l) into twelve 30-1 aquaria under light intensities of 0, 100, 200, 500 and 1000 lx, with three replicate aquaria per treatment. Temperature was maintained at $20^{\circ}C$ and salinity was 35 psu. Larvae were fed the rotifer Brachionus rotundiformis at a density of five rotifers/ml. Feeding incidence was measured as the percentage of larvae with prey in the digestive tract. Feeding intensity was evaluated as the number of prey in the digestive tract of the larvae. Larvae fed in darkness (0 lx) had significantly lower (P < 0.05) feeding incidence ($13{\pm}0.05%$ larvae with prey) and feeding intensity ($1.00{\pm}0.05$ rotifers per larva) than those larvae fed at 100 ($30{\pm}0.07%$, $1.17{\pm}0.09$ rotifers per larva), 200 ($43{\pm}0.08%$, $1.24{\pm}0.11$ rotifers larvae$^{-1}$), 500 ($53{\pm}0.08%$, $1.48{\pm}0.14$ rotifers per larva) and 1000 lx ($60{\pm}0.08%$, $1.38{\pm}0.13$ rotifers per larva). The feeding incidence of S. japonicus larvae increased with light intensity while feeding intensity showed no significant difference (P > 0.05) between light treatments.

• Current Research on Agriculture and Life Sciences
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• 제32권4호
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• pp.185-188
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• 2014

The movement, survival, and weight gain of Helicoverpa armigera $H{\ddot{u}}bner$ (Lepidoptera: Noctuidae) first instar larvae were studied on CB9, CB10 and SR05 cotton varieties under field conditions. The neonate H. armigera were released on the cotton varieties at the squaring stage of the plants and, after a period of 72 hours, the survival, weight gain, and final location of the larvae were observed. While the different cotton varieties had no effect on the survival and weight gain of the larvae, the release locations on the cotton varieties had a significant influence on the larval survival and weight gain. The larvae fed small squares of the cotton varieties were significantly heavier and showed a higher mortality than the larvae fed leaflets and mature leaves. For the cotton varieties in this study, the larvae released on leaflets showed a significantly higher rate of recovery compared to the larvae released on mature leaves and squares. This study also found that that the larvae on leaflets did not move up or downward unlike the larvae on mature leaves and squares. This information on the foraging behavior of larvae on cotton varieties will assist researchers to interpret field data and thereby help with the development of pest management decisions.

• International Journal of Industrial Entomology and Biomaterials
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• 제46권2호
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• pp.34-40
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• 2023

As agricultural production increases due to population growth, agricultural by-products that are generated at all production stages increase commensurately. Black soldier fly (BSF) (Hermetia illucens) treatment has potential as an environmentally friendly process to combat the environmental pollution caused by agricultural by-products. This study examined the utilization of BSF larvae in the decomposition of the by-products of apples and mandarins, fruits commonly produced in South Korea. The BSF test larvae were fed apple pomace or mandarin waste, and the control larvae were fed calf feed. Larval weight and size were measured at 4-day intervals until larvae reached the pre-pupal stage. Larval development time, survival rate, and BSF fecundity rate were calculated for all three substrates. Waste reduction and bioconversion ratios were also calculated. The developmental time of larvae fed with apple pomace and mandarin waste was greater than that of the control larvae. The average weight of larvae fed with the fruit by-products was less than that of the control. There was no significant difference in the survival rate of BSF larvae or the fecundity rate of BSF between the substrates used in this study. BSF larvae decomposed 48.0% and 61.5% of apple pomace and mandarin waste, respectively. The bioconversion efficiency rates of BSF larvae fed with apple pomace and mandarin waste were 9.1% and 12.1%, respectively. These results indicated that decomposition of single fruit by-products by BSF larvae is an environmentally friendly and effective bioconversion process.

• 한국환경보건학회지
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• 제29권4호
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• pp.17-20
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• 2003

The results of study of the parasites of rockfishes, Sebastes spp. collected at Oregon coast aquarium during April 6 to June 30, 2002 are presented. Six species of parasites were recovered from examination of 19 rockfishes with an incidence of infection of 42.1 %. This study investigated parasitic infestation of 7 black rock-fish, Sebastes melanops ; 3 quillback rockfish, S. maliger ; 2 yellowtail rockfish, S. flavidus ; 3 canary rockfish, S. pinniger 2 yelloweye rockfish, S. ruberrimus ; 2 tiger rockfish, S. nigrocinctus. Sebastes spp. from aquarium were found to be infested with parasites: Mycrocotyle sebastis, Megalocotyle trituba, Clavella uncinata, Anisakis simplex larvae, Contracaecum sp. larvae, Pseudoterranova decipiens larvae. Prevalence and mean intensity of rockfishes were infected respectively as follows: 21.1%, 4.0 of M. sebastis, 10.5%, 55.5 of M. trituba, 21.1%, 34.3 of A. simplex larvae, 10.5%, 15.0 of Contracaecum sp. larvae, 10.5%, 8.5 of Pseudoterranova decipiens larvae and 10.5%, 5.0 of Clavella uncinata. This study reveled that gills and gastrointestinal tracts of S. pinniger were heavily infested with M. trituba and A. simplex larvae.

• The Korean Journal of Ecology
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• 제21권6호
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• pp.799-804
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• 1998

laboratory experiments were conducted to determine the effects of Dimilin, an insect growth regulator which acts to inhibit chitin synthesis, during the larval development of liocarcinus corrugatus Pennant. The larvae was exposed to control (10 ppb acetone sea water and untreated sea water solution) and five concentrations 0.1, 1.0, 5.0, 10.0 and 25.0 ppb of both TG and WP-25 formulations of Dimilin from the hatching to the megalopal stage, and the effect of Dimilin on development of the larvae were determined. Two formulations (TG and WP-25) had different effect on the different stages in L. corrugatus. and early stage larvae of L. corrugatus were more sensitive to TG than to WP-25. Concentrations of diflubenzuron >5.0 ppb are lethal to L. corrugatus larvae upon chronic exposure. Lethal concentrations are defined here as those in which less than 10% of the larvae survived to the megalopal stage. However, Dimilin (TG and WP-25) showed no significant effects on developmental time of L. corrugatus larvae.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제1권1호
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• pp.61-67
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• 1997

The effects of Insect growth regulator Dimilin which interfere with the synthesis of chitin in the cuticle of insect larvae were investigated at various concentrations using the copepod larvae of Tigriopus japonicus Mori. The larvae were cultured at control, 1, 5, 10, 20, 50, and 100 ppb Dimilin solutions and three replicate experiment were carried out to give correct analysis. Lethal effects of Dimilin on larvae of T. japonicus occurred above 1 ppb Dimilin solution after 8 days. $LC_{50}$ of larvae was 50 ppb Dimilin on the 4th day. Lethal effects of Dimilin on adults or T. japonicus occurred above 20 ppb Dimilin solution after 13 days. $LC_{50}$ of adults was 50 ppb Dimilin on the 12 days. Egg viability has little relation to Dimilin solution concentrations.