• Korean journal of applied entomology
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• v.37 no.2
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• pp.127-135
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• 1998

To study overwintering biology of the oriental tobacco budworm (OTB), Helicoverpaa.ssulta, OTB larvae were collected from middle and southern region of Korea in the autumn and rearedto diapausing pupae. Diapausing pupae were held at two different locations (Suwon and Chinju) and wererecollected in the spring to observe adult emergence rate and duration to adult emergence at 25$^{\circ}$C. Thesurvivorship of overwintering pupae was less than 5% when the pupae were buried in the soil in 20cmdepth. However, more than 60% of the pupae survived when they were kept in the plastic cup withartificial diet and were buried in the soil. The mean developmental periods of overwintering pupae at 25"C varied from 20.4 days to 43.9 days depending on years and locations where larvae were collected andpupae were held. The proportion of individuals which required longer than 30 days for development washigher in the population from the middle regions than those of southern regions. However, the proportiondecreased when the pupae collected from middle regions were held at Chinju, southern region. Chinju, southern region.

• Korean journal of applied entomology
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• v.53 no.4
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• pp.355-365
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• 2014

It has been unclear whether the diamondback moth, Plutella xylostella can overwinter in Korean field conditions. This study determined overwintering conditions of P. xylostella by conducting field exposure tests based on its cold tolerance and monitoring overwintering populations by direct examination of overwintering larval habitats and capturing adults with sex pheromone traps. In addition, the overwintering populations were analyzed using polymorphic genetic markers to trace their sources. When all immature stages of P. xylostella were exposed to $-5^{\circ}C$, which was the temperature much above their supercooling points, they significantly suffered with direct cold injuries, where larval stage was most tolerant to the cold injury. However, the exposure to $5^{\circ}C$ for a long period (4 weeks) did not give any significant cold injury to nonfeeding stages, while this treatment gave lethality to larval stage without diet. When all developmental stages of P. xylostella were exposed to open field conditions during winter, they exhibited significant decreases of survival rates. However, some protected and indoor conditions reduced the cold injuries and the diet provision significantly increased larval survival rates. Adult monitoring with sex pheromone during winter period indicated that the first captures were observed at similar periods at different locations (${\approx}260$ Km apart). The overwintering adults were captured until early April. Genetic variation of these overwintering populations was analyzed with polymorphic molecular markers, indicating significant genetic divergences among the overwintering populations. This study indicates that P. xylostella can overwinter in southern Korean fields or some protected greenhouses with host plants.

• The Korean Journal of Ecology
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• v.13 no.1
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• pp.59-66
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• 1990

Changes in water potential, lethal temperature and carbohydrate content in the leaves of wintergreen (Pyrola japonica) during overwintering were investigated. Leaf water potential was kept at -2 bars in the tender stage before October, decreased to -46 bars in the dormancy stage and increased to -2 bars again after dehardening Lethal temperatures of the leaf tissue were $-7^{\circ}C$ in the tender stage and $-7^{\circ}C$ in the dormancy stage, but did not recover up to that of the tender stage during dehardeding. Peak of soluble sugar content coincided with the nadir of the leaf water potential. There were close relationships among daily minimum air-temperature, leaf water potential and lethal temperature in changing patterns during overwintering.

• Korean journal of applied entomology
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• v.50 no.1
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• pp.29-37
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• 2011

A remote sensing pheromone trap called IT pheromone trap (Korean patent: 10-0982563) was applied to monitor overwintering population changes of the oriental fruit moth, Grapholita molesta, for three successive years in apple orchards. Males of the overwintering populations were attracted during April and May. However, the occurrence peak was delayed and extended to early June in 2010, at which the average spring temperature was significantly lower than the previous years. These overwintering populations could be monitored by the remote-sensing pheromone trap. When the remote-sensing pheromone traps were deployed to apple orchards of different provinces in Korea in 2010, the maximal overwintering populations of G. molesta were monitored at May in all areas. However, the population sizes monitored were significantly different among different localities. This study suggests a practical application of IT pheromone trap to monitor G. molesta in field conditions.

• Korean journal of applied entomology
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• v.54 no.4
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• pp.351-357
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• 2015

The two-spotted spider mite Tetranychus urticae Koch, overwinters in apple culture areas of apple orchards. The mite overwinters in various places on the apple trees, usually in groups of 5-15 females. Overwintering females were mostly found in bark crevices with the hibernation cocoons of the oriental fruit moth, Grapholita molesta Busck. They were also found in small crevices of the bark, and in pedicels left after fruit harvesting. Furthermore, overwintering females were found on rough bark at the bases of buds and spurs, on small limbs and twigs, and in limb crevices and forks. Empty scales of dead diaspidids and coccids, as well as cocoons of lacewings and mummies of parasitized aphids sporadically found on trees, were found to be less common overwintering sites for females of the two-spotted spider mite. In two successive years, the mortality of overwintering females was very high, reaching approximately 72 and 80%. This could be due to the low temperature of winter season in Korea and the low cold tolerance of the mite.

• Ocean and Polar Research
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• v.26 no.4
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• pp.679-684
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• 2004

To determine if Antarctic krill employ body shrinkage as one of its overwintering mechanisms in the field, Euphauia superba and Euphausia crystallorophias were collected during fall and winter in and around Marguerite Bay through US Southern Ocean GLOBEC field programs during fall and winter 2001 and 2002. The relationships between the body length and weight of both krill species were exponentially correlated with no significant differences between the two species (p>0.05). The ratio between eye diameter and body length of individual krill was examined in an expectation that it could be used as an indicator of the body shrinkage as previously suggested by Shin and Nicol (2002). These ratios were significantly different between the two krill species. Especially, E . crystallorophias had bigger eyes than E. superba. In both krill species, eye diameters were highly correlated with body lengths (regression coefficients ${\geq}0.70$). For E. crystallorophias, no significant differences of the ratio of eye diameter/body length were detected between fall and winter. Even though the ratios for E. superba were seasonally varied, it was not clear whether body shrinkage was an actual and critical overwintering mechanism for the krill population found in this study area. These results suggest that some individuals of E. superba might experience the body shrinkage during a part of their liff, but this morphological index alone (eye diameter/body length) may be insufficient to unambiguously separate the shrunk krill from the non-shrunk ones in the field-collected animals.

• Korean journal of applied entomology
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• v.45 no.2 s.143
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• pp.235-240
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• 2006

Efficacies of two commercial mating distruptor (SPLAT$^{(R)}$ and Isomate$^{(R)}$-ROSSO) were evaluated on field overwintering populations of Oriental fruit moth, Grapholita molesta (Busck), in four apple orchards. Based on the monitoring with sex pheromone traps, all the orchards (Youngchun, Kyungsan, Chungsong, and Youngju in Korea) exhibited significant overwintering populations from late April to late May. Both mating disruptors that were applied 10 days before the monitoring period significantly inhibited the male orientation to the monitoring lures, in which SPLAT type was more effective than Isomate type in the disrupting efficacy. The disruption of male orientation was highly correlated with the reduction in the early leaf damage caused mostly by G. molesta.

• Korean journal of applied entomology
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• v.54 no.4
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• pp.303-310
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• 2015

The diamondback moth, Plutella xylostella, overwinters in some protected areas in Korea. Using a sex pheromone trap, the adults were monitored since the occurrence of the overwintering populations. In Andong, P. xylostella exhibited four adult peaks in a year. Biological characters, such as cold tolerance, insecticide susceptibility, and developmental rate, were analyzed and showed a significant variation among different local overwintering populations. Population genetic variation was assessed with molecular markers, in which the initial high genetic variation among the overwintering populations decreased with the progress of seasons. These results suggests that there may be a significant migration of P. xylostella to decrease the genetic variation among the different local populations that are different in biological characters.

• Korean journal of applied entomology
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• v.23 no.2 s.59
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• pp.132-136
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• 1984

This study was conducted to investigate the bionomics of Curculio sikkimensis in Chonnam province from 1981 to 1983. Damage rates of the chestunt were $26.4\%$ in Damyang, $21.1\%$ in Gwangyang, and $12.9\%$ in Seungju. Adults occurred from the mid-July to the mid-September and showed peak from the mid-August to the early-September. Larvae escaped the chestnut from the early-October to the early-November. Overwintering larvae emerged $3.3\%$ in the first year, $22.78\%$ in the second year and continously overwintered $1.67\%$ in the third year. Larvae showed the highest distribution at $1.67\%$ of soil depth during the overwintering. Mortality of overwintering larvae and course of time showed the linearly correlation. Period of each stage was 5.9 days for egg and 17.17 days for pupa. Adult longevity was 9.10 days for female and 7.03 days for male.

• Journal of Ecology and Environment
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• v.47 no.2
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• pp.14-26
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• 2023

Background: An important consideration for the risk assessment of transgenic plants is their overwintering potential in a natural ecosystem, which allows the survival of the seed bank and may lead to seed reproduction. Here, we investigated the overwintering of sunflower (Helianthus annuus L.) seeds in the laboratory (temperatures: -5, -1, 5, and 10℃) and in the field (burial depth: 0, 5, 15, and 30 cm) as a case study to examine the invasiveness of transgenic crops. Results: Sunflower seeds germinated when incubated at 5℃ and 10℃ for 2, 4, 6, and 12 weeks but not when incubated at -5℃ or -1℃. However, the seeds incubated at -5℃ or -1℃ germinated when they were transferred to the optimal germination temperature (25℃). Up to 16.5% and 15.0% of seeds were dormant when cultured at sub-zero temperatures in a Petri dish containing filter paper and soil, respectively. In the field trial, soil temperature, moisture, and microbial communities differed significantly between soil depths. Germination-related microorganisms were more distributed on the soil surface. Seeds buried on the surface decayed rapidly from 4 weeks after burial, whereas those buried at depths of 15 cm and 30 cm germinated even 16 weeks after burial. No dormancy was detected for seeds buried at any depth. Conclusions: Although sunflower seeds did not overwinter in situ in this study, we cannot exclude the possibility that these seeds lie dormant at sub-zero temperatures and then germinate at optimal temperatures in nature.