• Journal of Sericultural and Entomological Science
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• v.50 no.2
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• pp.109-111
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• 2012

The success of biological control depends upon the standard setting and effective mass rearing of natural enemies. In this work, we have investigated cold storage condition of Hypoaspis aculeifer(Canestrini) and Tyrophagus putrescentiae(Schrank). which has been stored at 8, $12^{\circ}C$, RH $70{\pm}5%$, in dark condition. An appropriate temperature of cold storage was $12^{\circ}C$ with wheat bran(50%) and rice bran(50%) for T. putrescentiae. 7o% of T. putrescentiae and H. aculeifer could survive for 28 days and 70 days at $12^{\circ}C$. After storing at $12^{\circ}C$ with prey mite for 28 days, 56 days and 84 days, their reproduction rate showed similar resultes.

• Journal of Wetlands Research
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• v.25 no.4
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• pp.257-266
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• 2023

Amphibian populations are declining globally, pushing many species to the brink of extinction. To promote biodiversity and sustainable management, countries are actively researching amphibian reproductive ecology. Sperm cryopreservation is a crucial assisted reproductive technology that aids in preserving the genetic diversity of amphibians. However, because amphibian sperm cells are sensitive to osmotic stress, the optimal cryopreservation method therefore differs from species to species. This literature review offers an overview of the significance of developing cryopreservation techniques for amphibian conservation and highlights the need to create optimal cryopreservation methods and the introduction of long-term monitoring (e.g., fertilization success and offspring reproduction) to advance cryopreservation technology development. This review can be used as basic research data for amphibian conservation methods.

• Korean Journal of Environmental Biology
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• v.40 no.4
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• pp.550-555
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• 2022

Perilla plant is a special crop that is used as oilseed and food in Korea. Root lesion nematodes have caused great damage to perilla plants, so for effective management of root lesion nematodes, it is necessary to understand their ecology in perilla. In this study, we investigated the effect of temperature in the development of Pratylenchus penetrans (Pp) and Pratylenchus vulnus (Pv) when the nematodes infected the perilla plant. To estimate the effect of temperature, we assessed the reproduction factor (RF); final population/initial population(Pf/Pi) of these two nematode species. We used perilla plants as inoculated hosts and investigated the density of nematodes at 10 weeks after inoculation. As a result, the RF of Pp was highest at 20℃ (0.41 (1st test), 2.2 (2nd test)) followed by 25, 30, and 15℃. The RF of Pv was highest at 30℃(9.84 (1st test), 31.39 (2nd test)), followed by 25, 20, and 15℃. Comparing the RF by temperature between Pp and Pv, Pv was higher than Pp at all temperatures used in the test. This study showed the optimal development temperature of Pp was 20-25℃ and Pv was 30℃, respectively.

• Journal of Ecology and Environment
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• v.30 no.4
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• pp.319-324
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• 2007

To investigate the impacts of transgenic rice on freshwater organisms, we conducted two life table experiments using Daphnia magna for fifteen and twenty days, respectively. We examined life history traits such as population growth rates (r), reproductive rates ($R_0$), generation times, and survivorship. In the first experiment, we used non-drought-stressed transgenic and non-transgenic rice harvested in 2005. In the second study, we used non-transgenic and transgenic rice harvested in 2006 following drought stress. Each experiment involved three treatments in which D. magna neonates were fed with Selenastrum capricornutum (control treatment) and S. capricornutum with 5% aqueous extracts of non-transgenic rice (N-T) and transgenic rice (T). In the first experiment, D. magna showed reduced population growth rates and lowered fecundity in the N-T and T treatments. In the second experiment, D. magna receiving both transgenic and non-transgenic rice extracts showed very high mortality, low population growth rates and reproduction rates. We could not detect any significant negative effects of extracts from transgenic rice on D. magna life history traits at 95%.

• Korean Journal of Ecology and Environment
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• v.45 no.4
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• pp.420-443
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• 2012

An Individual-Based Model (IBM) was developed by employing natural and toxic survival rates of individuals to elucidate the community responses of benthic macroin-vertebrates to anthropogenic disturbance in the streams. Experimental models (dose-response and relative sensitivity) and mathematical models (power law and negative exponential distribution) were applied to determinate the individual survival rates due to acute toxicity in stressful conditions. A power law was additionally used to present the natural survival rate. Life events, covering movement, exposure to contaminants, death and reproduction, were simulated in the IBM at the individual level in small (1 m) and short (1 week) scales to produce species abundance distributions (SADs) at the community level in large (5 km) and long (1~2 years) scales. Consequently, the SADs, such as geometric series, log-series, and log-normal distribution, were accordingly observed at severely (Biological Monitoring Working Party (BMWP<10), intermediately (BMWP<40) and weakly (BMWP${\geq}50$) polluted sites. The results from a power law and negative exponential distribution were suitably fitted to the field data across the different levels of pollution, according to the Kolmogorov-Smirnov test. The IBMs incorporating natural and toxic survival rates in individuals were useful for presenting community responses to disturbances and could be utilized as an integrative tool to elucidate community establishment processes in benthic macroin-vertebrates in the streams.

• Journal of Ecology and Environment
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• v.44 no.1
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• pp.41-44
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• 2020

The Chinese many-toothed snake (Sibynophis chinensis) is an endangered species in South Korea. To determine its reproductive activity, here we captured a gravid S. chinensis from Mulyeongari Oreum Wetland Conservation Area, Jeju Island, on May 27, 2018, and reared it at Animal Taxonomy and Morphology Laboratory, Jeju National University, South Korea. The snake oviposited a clutch of six eggs between June 12 and 20, 2018, with an average size of 24.86 ± 1.36 mm in length and 9.86 ± 0.49 mm in width, which were artificially incubated at a constant temperature of 27 ℃. After incubating for 34-41 days, five of these six eggs successfully hatched. Average snoutvent length (SVL), tail length (TL), and body weight (BW) of hatchlings were 136.5 ± 5.17 mm, 47.76 ± 2.80 mm, and 1.66 ± 0.12 g, respectively. This study observed the reproductive activity of S. chinensis and characterized its eggs and hatchlings for the first time, providing valuable information for the long-term conservation plan of S. chinensis in South Korea.

• The Korean Journal of Ecology
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• v.18 no.4
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• pp.513-513
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• 1995

The central theme of Habital heterogeneity is to provide animals with habital complexity or structural diversity and to allow resource partitioning among individuals. In turn, the leads to population stability because prey can escape more easily with more hiding places causing less population fluctuation. Species diversity is characterized due to more potential niches both horizontally and verticall. Empirically, in homogeneous habitats population was less abundant, reproduction and survival were lower, spacing behavior, competition and dispersal were higher than in heterogeneous habitats. The results imply that diversity and conservation of species can be maintained through providing heterogeneous habitats.

• The Korean Journal of Ecology
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• v.25 no.6
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• pp.383-389
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• 2002

Pb and Cd concentrations and reproductive progress of feral pigeons were investigated in urban (Seoul) and industrial complex (Ansan) areas from November 2000 to May 2001. Results of the Pb analysis for the feral pigeons from the Ansan industrial complex (egg contents: 1.13 $\mu$g/wet g, bones of adult: 10.5 $\mu$g/wet g) and Seoul (1.64 $\mu$g/wet g, 29.5 $\mu$g/wet g, respectively) indicated that the Pb level of eggs and bones of adults were significantly different between the two colonies (p<0.05). Cd concentrations in liver and kidney of adult pigeons were also significantly different between the Ansan (liver: 0.14 $\mu\textrm{g}$/wet g, kidney: 0.43 $\mu$g/wet g) and Seoul (liver. 0.24 $\mu$g/wet g, kidney: 1.05 $\mu$g/wet g) colonies. (p<0.05). However, egg size and thickness, incubation period and nestling growth rates did not differ between the study areas. Also, clutch size, number of young hatched per nest and number of young fledglings per nest did not significantly different in the noted areas. Considering the lead and cadmium concentrations of pigeons, these were not as high as those considered as results in toxic effects in other species, and the biological significance from these level differences is uncertain.

• Journal of Ecology and Environment
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• v.38 no.1
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• pp.1-14
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• 2015

Whilst it is clear that increasing temperatures from global environmental change will impact the positions of alpine treelines, it is likely that a range of regional and local scaled factors will mediate the overall impact of global scale climate drivers. We summarized 12 categories of abiotic and biotic factors as 4 groups determining treeline positions. First, there are global factors related to climate-induced growth limitation and carbon limitation. Second, there are seven regional and local factors related to treeline dynamics including frost stress, topography, water stress, snow, wind, fire and non-fire disturbance. Third, species-specific factors can control treeline dynamics through their influence on reproduction and life history traits. Fourth, there are positive feedbacks in structuring the dynamics of treelines. Globally, the commonly accepted growth limitation hypothesis is that growth at a treeline is limited by temperature. Meanwhile, positive feedbacks between canopy cover and tree establishment are likely to control the spatial pattern and temporal dynamics of many treelines. The presence of non-linear dynamics at treelines has implications for the use of treelines as barometers of climate change because the lagged responses and abrupt shifts inherent in non-equilibrium systems may combine to mask the overall climate trend.

• Journal of Ecology and Environment
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• v.38 no.1
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• pp.39-45
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• 2015

In this study, the dependence of local conspecific abundance on seed set and predation was examined, and determinates of population density of the temperate tree species Carpinus laxiflora (Betulaceae) in Inagi city, Tokyo, Japan were identified. During a good seed year (2013), seeds were sampled from 27 individuals and categorized as Sound, Empty, Predated, Immature, Decayed, or Broken. Empty seeds were identified as those that failed to fertilize and predation rates were defined as the proportion of seeds that were affected by predators. The proportion of the seed set that was fertilized was significantly positively correlated with local abundance of conspecific trees, while the proportion of seeds that escaped predation was significantly negatively correlated with local abundance of conspecific trees. Thereby, the production of Sound seeds was highest at sites with moderate local conspecific abundance. Although this phenomenon was only observed in a few cases, it clearly showed optimal reproductive success under conditions of moderate density of conspecific reproductive adults, suggesting a mechanism that controls the population density of this species.