• Korean journal of applied entomology
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• v.34 no.4
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• pp.321-327
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• 1995

This study was conducted to determine the winter ecology of the small brown planthopper (SBPH), laodelphax striatellus Fallen, in Milyang, east Kyungsangnamdo province. The age distribution in the overwintering SBPH population varied according to collection dates. In early December, the population distribution was 60% 4th instar, 30% 3rd instar, 6% 5th instar, 3.4% 2nd instar with very few adults and 1st instar. In early March 5th instars had the highest propotion (47-50%) with 4th instar 44-46%. In early April the adult population was 75-81% of the population. The averaged nymphal instar converted the age distribution of he overwintering SBPH in to the into the numerical values tended to increase continuously. However, there were some differences in the averaged nymphal instar of overwintering SBPH annually and these differences resulted from different age distribution of the overwintering SBPH due to different annual temperature fluctuations during overwitering periods. The weight of the overwintering SBPH increased continuously during overwintering periods. The collection density of the overwintering SBPH population was significantly higher on the levee than in the barley field. Percent nymphal parasitism by haplogonatopus atratus in the overwintering SBPH population averaged about 21% regardless of overwintering years.

• Journal of the Korean Society of Tobacco Science
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• v.11 no.1
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• pp.41-48
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• 1989

The significance of soil and/or rhisosphere populations of Erwinia carotovora sobsp. carotovora (Ecc) as a source of primary inoculum for tobacco hollow stalk disease has been demonstrated conclusively. The survival of Ecc in field soils fter overwintering was estimated by using the enrichment technique. The population number of pectolytic erwinia (PE) in field soils relatively decreased at the rate of 102-104 colony forming unit(CFU) per g of soil after overwintering. Higher level of PE population overwintered in the rhlzosphere foils of tobacco stubbles and detected more frequently in rhizosphere soils of weed plants than in those of bare fields. All of the tobacco stubbles collected from fields where tobacco had been grown the previous year contained Ecc. The more survived population number of PE at the 30cm depth of artifitiany infested soils than at the upper of those by introducing with diseased tobacco plant tissue after overwintering. Ecc overwintered effectively in rhizosphere soils of tobacco stubbles, overwintered weeds and tobacco debris in field soils.

• Korean journal of applied entomology
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• v.35 no.2
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• pp.140-145
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• 1996

This study was conducted to investigate the winter ecology of the green leafhopper(GLH), Nephotettix cincticeps Uhler, in Milyang, south-eastern part of Korea from early December to early April during 1990 to 1992. The instar distribution in the overwinteing GLH population collected in December 5th was most of 4th instar 77% to 79% followed by 3rd instar 15% to 17% and 5th instar 3%. These instar distribution rate in the overwintering GLH was changed with collecting dates during overwintering periods of the GLH. Among the GLH population collected, as a result, the distribution rate of the 5th instar was significantly increased in February 20th and was most of 5th instar 70% to 71% in March 19th and was adult 47% to 50% in April 8th. During two overwintering periods of the GLH, the averaged instars converted the instar distribution of the overwintering GLH into the numerical values were 3.91 and 3.86 instar in December 5th, 4.11 and 4.07 instar in February 20th, 4.75 and 4.79 instar in March 19th and 5.42 and 5.45 instar in April 8th respectively. In addition to, the developmental index between pre-collected date and post-collected date of the overwintering GLH was roughly more than 1.0 value. It means that the overwintering GLH was developed without cease though the development was very slow and deponded upon air temperature. The overwintering GLH population were significantly more collected at the levee than at the barley field.

• 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.40 no.3
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• pp.227-233
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• 2001

Four polymorphic allozymes were used for genetic analysis of overwintering populations of field diamondback moth, Plutella xylostella (Linne). Different allele frequencies were found among three local populations of Andong, Youngchon, and Yangsan in all loci. Two allozyme loci (acid phosphatase and phosphoglucomutase) showed significant deviation from Hardy-Weinberg equilibrium in allele frequencies among these populations. Estimated Nei's genetic distance varied from 0.0151 between Yangsan and Youngchon to 0.0877 between Andong and Youngchon. Compared with the previous genetic distances in this moth, a little higher genetic differentiation among these overwintering populations suggests that there would be a specific genetic bottleneck in each local population during overwintering period.

• 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.

• Animal cells and systems
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• v.7 no.2
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• pp.111-117
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• 2003

Ecological aspects of Cryptocercus kyebangensis life history were investigated via laboratory rearing and field observations. The number of antennal segments and head width were used to classify the first four instars. The results, which combine both the field collection and the laboratory rearing, indicate that eleven instars occur in C. kyebangensis. It supports the proposal on the number of instars of Park and Choe (2003c) based on field collections. A total of 388 nymps from 13 colonies were collected prior to winter to investigate overwintering stages. Of them,4％ (n = 17) were the second instars, 57％ (n = 220) were the third instars, and 39％ (n = 151) were the fourth instars, respectively. Thus, most of them overwinter in the third or fourth instars. The results indicate that young nymphs of C. kyebangensis have to reach at least 3rd or 4th instar to survive low temperature environment of winter. According to seasonal dynamics of populations, C. kyebangensis reaches adulthood in the summer of the fourth or fifth year (4-5 yr span) after their birth.

• Korean journal of applied entomology
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• v.48 no.2
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• pp.165-170
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• 2009

This study was conducted to investigate specific stages and distribution of overwintering nymphs of green rice leafhopper, Nephotettix cincticeps by measuring head capsule width. The nymphal head capsule width of the 1st instar to the 5th instar was 0.381, 0.502, 0.673, 0.979 and 1.128 mm, respectively. lts coefficient variation was 5.3, 4.0, 3.0, 4.5 and 5.3%, respectively. Growth ratio of each instar was not significantly different among 2nd to 4th instars as 1.31 to 1.34, but for the 5th instar it decreased as 1.28. The logarithm of the nymphal head capsule width was regressed as a function of the stage number of insects, resulting in LogY = 1.4627 + 0.1192X ($r^2= 0.9993$). Also fitness to the Dyar's law for the nymphal head capsule width of each instar was 98% or over and the Dyar's constant (K) was 1.316. The occurrence of N. cincticeps was maximum at the end of January with 195 individuals/0.25 $m^2$. The most abundant instar in the overwintering N. cincticeps population was 4th instar accounting for over 90%. Population of the 5th instar began to increase from mid-March, and adults began to occur in early April.

• Korean journal of applied entomology
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• v.52 no.2
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• pp.71-74
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• 2013

The moving period and overwinteing site of Scrobipalpa salinella (Zeller) were investigated in Gimje, Jeonbuk, and Shinan, Jeonnam in the glasswort field. Densities of Scrobipalpa salinella larvae were started to increase from mid-September in halophytes, such as Suaeda asparagoides, S. japonica, and S. maritima, rather than glasswort. S. salinella was overwintering inside the halophytes in old larva. Density ratio of overwintering S. salinella in Suaeda asparagoides, S. japonica, and S. maritima were 20.5, 28.4 and 51.1%, respectively. Overwintering population was highest in S. maritima among halophytes. The occurrence of first adult in the next spring was from April 19 to April 20 in Gimje, Jeonbuk, and Shinan, Jeonnam.

• 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.