• The Korean Journal of Ecology
• /
• v.21 no.6
• /
• pp.799-804
• /
• 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.

• Parasites, Hosts and Diseases
• /
• v.54 no.1
• /
• pp.103-107
• /
• 2016

The objective of this study was to evaluate the effects of several different commercial disinfectants on the embryogenic development of Ascaris suum eggs. A 1-ml aliquot of each disinfectant was mixed with approximately 40,000 decorticated or intact A. suum eggs in sterile tubes. After each treatment time (at 0.5, 1, 5, 10, 30, and 60 min), disinfectants were washed away, and egg suspensions were incubated at $25^{\circ}C$ in distilled water for development of larvae inside. At 3 weeks of incubation after exposure, ethanol, methanol, and chlorohexidin treatments did not affect the larval development of A. suum eggs, regardless of their concentration and treatment time. Among disinfectants tested in this study, 3% cresol, 0.2% sodium hypochlorite and 0.02% sodium hypochlorite delayed but not inactivated the embryonation of decorticated eggs at 3 weeks of incubation, because at 6 weeks of incubation, undeveloped eggs completed embryonation regardless of exposure time, except for 10% povidone iodine. When the albumin layer of A. suum eggs remained intact, however, even the 10% povidone iodine solution took at least 5 min to reasonably inactivate most eggs, but never completely kill them with even 60 min of exposure. This study demonstrated that the treatment of A. suum eggs with many commercially available disinfectants does not affect the embryonation. Although some disinfectants may delay or stop the embryonation of A. suum eggs, they can hardly kill them completely.

• Animal Systematics, Evolution and Diversity
• /
• v.18 no.1
• /
• pp.35-48
• /
• 2002

Larval development of Chirona cristatus Ren and Riu, 1978, found in the low part of rocks in the intertidal clone or the shell of scallops, was described in detail and compared with those of other known barnacles. Durations from nauplius through cyprid to pinhead stage are three weeks at 20$\pm$0.5$^{\circ}C$. Trilobed labrum bearing three groups of slender hairs and frontolateral horns folded under the anterior cephalic shield margin are diagnostic features through all nauplius stages. The posterior border of the cephalic shield bears a pair of cephalic shield spines in nauplius stages IV,V and Ⅵ. There is no specific hispid sets at the fourth group of the antennal endpodite. The dorsal thoracic spine, abdominal process and posterior shield spine haute numerous small spines Morphological features such as the cephalic shield, labrum, abdominal process, antennules, antennae and mandibles in all nauplius and cyprid stages are illustrated and described. The numerical setations of antennule in this species are found to be practically helpful for intraspecific identification of barnacle nauplius stages without dissection.

• Journal of Sericultural and Entomological Science
• /
• v.37 no.2
• /
• pp.121-126
• /
• 1995

The effects of oral application of fenoxycarb, the commercial formulation Insegar, to the selected developmental stages of the silkworm, Bombyx mori, was investigated. An oral application of the chemical to the silkworm from the 2nd- to the 5th-instar larvae delayed the larval development upto more than 40 days and increased the larval body weight in the range of 1.1 to 1.7 folds. When the chemical was orally applied to the final instar larvae, spinning and pupation were prevented, and consequently permanent larvae occurred. The weight of a cocoon and its shell of silkworm(bombyx, mori, L) increased following the application of fenoxycarb to the 2nd- and the 3rd-instar larvae.

• Animal cells and systems
• /
• v.13 no.1
• /
• pp.59-69
• /
• 2009

This paper documents the defining morphological characteristics of the larval stages of Chionoecetes tanneri Rathbun, 1893, the grooved Tanner crab, from specimens reared in the laboratory. Chionoecetes tanneri larval stages include two zoeae and one megalopa. The first zoea is characterized by: six setae on the posterior margin of the carapace; postero-lateral spines on abdominal somites 3 and 4, extending beyond the posterior margin of adjacent somites and bearing 9-10 spinnules; 12 plumose setae and one stout distal plumose seta present on the margin of the scaphognathite of the maxilla; and one fused lateral spine and one articulated dorso-medial spine on each fork of the telson. The second zoea is characterized by: 9 setae on the postero-lateral margin of the carapace; a serrated mandible molar; a mandibular palp bud; 25-26 plumose setae on the margin of the scaphognathite of the maxilla; pereiopods with well-developed gills and buds; and four pairs of stout setae on the posterior margin of the telson. For the megalopal stage, the distinguishing characteristics include: a rostral spine equal in length to the supraorbital spine; six setae on the exopod of the uropod; and a single spine on the ischium of the second pereiopod. This study allows C. tanneri larvae to be distinguished from the larvae of known sympatric congeners. This information provides a basic taxonomic tool for researchers in fisheries management and zooplankton ecology who are addressing issues related to trophic interactions, metapopulation dynamics and ecosystem impacts in the evolving marine resource management strategies in the North Pacific, and those related to Chionoecetes species in particular.

• Ocean Science Journal
• /
• v.40 no.3
• /
• pp.177-182
• /
• 2005

The process of embryogenesis and larval development of the asteroid sea star Asterias amurensis $(U{\ddot{u}}tken)$ was observed, with special attention paid to morphological change and larval duration. In reproductive season, mature sea stars were collected under floating net cages, located in Tongyeong, southern Korea. The mature eggs are $138\;{\mu}m$ in average diameter, semi-translucent and orange in color, sperms in good condition appear light cream to white-gray in color. Embryos develop through the holoblastic equal cleavage stage and a wrinkled blastula stage that lasts about 9 hours after fertilization. Gastrulae bearing an expanded archenteron hatch from the fertilization envelope 22 hours after fertilization. At the end of gastrulation, rudiments of the left and right coelom are formed. By day 2, larvae possess complete alimentary canal and begin to feed. At this stage, the larva is called early bipinnaria. In 6-day-old larvae, the pre- and post- oral ciliated bands form complete circuits and the bipinnarial processes start to develop. By day 12, the lateral and anterior projection of the larval wall processes along the ciliated bands begins to thicken and curl, and the ciliated bands become more prominent. By day 32, early brachiolaria are presented with three pairs of brachiolar arms. Advanced brachiolaria with a well-developed brachiolar complex (three pairs of brachia and central adhesive disc) occur 6 weeks after fertilization. In the field, spawning of the sea star was observed in April to May, settlement form larvae and just settlements seem to occur from June to July, and early juveniles occur from August to September. Although we had not described the end of brachiolaria stage, it can be tentatively estimated that the duration of the pelagic stage of A. amurensis is 40 to 50 days.

• Korean Journal of Environmental Agriculture
• /
• v.35 no.4
• /
• pp.241-246
• /
• 2016

BACKGROUND: Recently, the widespread distribution of pesticides in the hive has been of concern about pesticide exposure on honeybee (Apis mellifera L.) health. Larval toxicity was adapted to assess the synergistic and antagonistic interaction of cumulative mortality to the honeybee larvae of the four most common pesticides detected in pollen. METHODS AND RESULTS: Acetamiprid($3.0{\mu}l/L$), chlorothalonil ($803.0{\mu}l/L$), coumaphos ($128.0{\mu}l/L$), and tau-fluvalinate ($123.0{\mu}l/L$) were tested in combination; binary, ternary and four component mixture. Larvae were exposed to four pesticides mixed in diet at the average levels detected in pollen. As a result, synthetic toxicity was observed in the binary mixture of acetamiprid with coumaphos. The binary and ternary component mixtures of tested pesticides have mostly demonstrated additive effect in larval bees. The significant antagonistic effects were found in four parings of mixtures including chlorothalonil added to acetamiprid/tau-fluvalinate or acetamiprid/coumaphos/tau-fluvalinate, and tau-fluvalinate added to acetamiprid/chlorothalonil or acetamiprid/coumaphos/chlorothalonil. CONCLUSION: Interactions between combinations of four pesticides showed mostly additive or antagonistic effects in larval bees. Therefore, predicting the larval mortality of pesticides mixtures on the basis of the results of single pesticide may actually overestimate the risk. We suggest that pesticide mixture in pollen be evaluated by adding their toxicity together for complete data on interactions.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.36 no.2
• /
• pp.107-112
• /
• 2003

Effect of PCBs on the skin and gill development of olive flounder, Paralichthys olivaceus were investigated by histological methodology and morphometric data. The olive flounder were exposed to limit concentration of effulent of PCBs (3.0 ${\mu}g/L$) for 60 days. Skin development can be classified into four stages: SSEL (simple squamous epithelial layer), MCA (mucous cell appearance) & CCA (club cell appearance) DLA (dermal layer appearance), and SEL (startification of epidermal layer) stages. Gill development had five stages: GFA (gill filament appearance), IGFE (identification of early gill filament epithelial cell) MCA (mucous cell appearance), PCA (pillar cell appearance), and FGL (formation of gill lamella) stages. The periods of structural completion of skin and gill were 22-30 days and 23-30 days after hatching in the exposure group respectively. The process of development of skin and gill of the exposure group was very similar to that of the control group. Therefore, PCBs (3 ${\mu}g/L$) have no influence on the development of skin and gill in the larval stage of olive flounder.

• Korean journal of applied entomology
• /
• v.36 no.4
• /
• pp.317-322
• /
• 1997

Hatched-larvae of the mulberry longicorn beetle, Apriona germari Hope, collected from mulberry fields were reared on artificial diet at 25$^{\circ}$C with 14 h light and 10 h dark to study the larval developmental characteristics. Artificial diet developed for rearing silkworm was used with minor modification adding mulberry branch powder. In case of artificial diet rearing, the head width of larval instar from the I st to the 12th instars was ranged from 0.12 to 0.69cm, and growth rate of each instar was significantly high between the I st and the 2nd instars. In addition, the weight of the 8th instar larvae was increased approximately 176-fold in comparision with that of the 1st instar larvae. Larval duration of each instar took long with larval developmental stages, and that of the 1st to the 9th or the 12th instars was 186.03 or 304.58 days, respectively. The survival rate of larvae was 40.8% by the 8th instar. The pupation rate was approximately 32.4%. Furthermore, although pupation stage was broadly appeared from the 7th to the I lth instars, pupation was majorly observed at the 8th and the 9th instars.

• The Korean Journal of Malacology
• /
• v.27 no.4
• /
• pp.307-315
• /
• 2011

Digestibility index of 12 phytoplankton species were invested during the larval development sizes. Ingestible size of phytoplankton varied depending on larval sizes: Isochrysis galbana, I. aff. galbana, Pavlova lutheri, Chlorella ellipsoidea, Nannochloris oculata was ingested 94.2-99.7% all larval sizes. Cheatoceros calcitrans, C. gracilis and C. simplex could ingest over 90.0% after umbo stage (mean shell length $189.3{\pm}13.8{\mu}m$). Phaeodactylum triconutum, Dunaliella tertiolecta and Tetraselmis tetrathele could not ingested D-shaped larvae (shell length $65.0-100.0{\mu}m$) but ingested 97.3-99.7%, 43.3-99.3%, 48.5-99.3% after then larval stages, respectively. But Thalassiosira weissflogii was ingested 1.0-1.7% only at full grown stage. Over 50.0% ingestion cell size was D-shape stage larvae with smaller than mean $102.3{\mu}m$ in shell length could ingest phytoplankton with $4.6{\mu}m$ in both major and minor axis and up to $9.3{\mu}m$ in minor axis basis for larger than mean $158.3{\mu}m$ in shell length, respectively. At all larval stages, phytoplankton with larger than $10.0{\mu}m$ in both major and minor axis could not be ingested.