• Korean journal of applied entomology
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• v.39 no.4
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• pp.275-279
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• 2000

Development of Bracon hebetor Say parasitizing Indianmeal moth (Plodia interpunctella (Hubner) was studied at five temperature conditions (17, 20, 25, 28 and 32$\pm$0.5$^{\circ}C$) under a photoperiod of 16 : 8 (L : D). Developmental period (mean$\pm$s.e.) of B. hebetor from egg to eclosion decreased from 28.6$\pm$0.50 to 9.3 $\pm$0.09 days and 28.1 $\pm$0.51 to 9.2$\pm$0.09 days for female and male, respectively, as the temperature increased from 17 to $32^{\circ}C$. The combination model provided a good description of the relationship between temperature and development. The low temperature thresholds were estimated to be 14.0, 12.8, 15.1$^{\circ}C$ for development of egg, larva and pupa. The thresholds for normal development (outside of the boundary layer of the development) were 14.0, 17.5, $15.1^{\circ}C$ for egg, larva and pupa, respectively, indicating that the larval stage is more sensitive to the low temperature than the other stages. The results suggested that the present B. hebetor population could be another ecological race adapting to the seasonal temperature conditions of this area.

• Korean Journal of Organic Agriculture
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• v.27 no.3
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• pp.327-339
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• 2019

The differential susceptibility of the two spotted spider mite, Tetranychus urticae and its predator, Phytoseiulus persimilis against extracts of Gleditsia japonica var. koraiensis, Camellia sinensis, Cinnamomum cassia, Lantana camara and their mixtures was evaluated. The plant extracts tested were much less toxic to P. persimilis than to T. urticae. The plant extracts tested had little effect on the survival of P. persimilis adult females. Moreover, reproduction of P. persimilis adult females and eclosion of eggs deposited by treated predators were not seriously affected. The treatments of the plant extracts tested showed no serious toxic effect on P. persimilis eggs and exhibited 84~100% hatchability. The treatments with mixtures 3 and 1 were effective against the adult females of T. urticae and yielded 76.0% and 72.7% adulticidal activity at 7 days after treatment, respectively. The treatment of mixture 2 revealed 63.3% adulticidal activity. Generally, the acaricidal activity of the individual treatment of each plant extract was lower than the mixtures. The adult females of T. urticae treated with mixtures 3 and 1 produced only 29.5~31.3% as many eggs as the control females did. All the plant extracts tested exhibited no noticeable toxic effect to the eggs of T. urticae. These results suggest that mixtures 3 and 1 might be used for the control of T. urticae, and expected to be promising candidates for use in integrated mite management program with P. persimilis.

• Development and Reproduction
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• v.2 no.1
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• pp.45-52
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• 1998

An enhncer detector line(EDL) having P[1ArB] insertion in X chromosome with expression of reporter gene (lacZ) in the polar cells and border cell of egg chamber was established and used to monitor the differentiation and migration of border cells during the oogenesis of Drosophila. differentiation of border cell from the anterior polar follicle cells was evident in stage-9 egg chamber of EDL149 which was characterized by migration of columnar follicle cells toward posterior of egg chamber surrounding the oocyte. Migration of border cells was observed in the stage-9 and -10 egg chambers. \beta -galactosidase activities were rapidly increased during the first 4 days after eclosion, and it coincided with the timing of border cell differentiation in the ovary during adult life. Homozygote of EDL149 showed some retardation of border cell migration , resulting absence of migration of some border cells in the anterior part of egg chamber or delayed migration of some border cells in the stage-10 egg chamber. These results suggest that the P[1ArB] of EDL149 is inserted at the locus of the structural gene required for the border cell migration. In addition to the expression in egg chambers, lacZ expression was also detected in the meiotic germ cells of testis and antenna, suggesting the possible requirement of the trapped gene function in these organ. this EDL and enhancer trapped gene might be useful for the study of developmentally regulated cell migration.

• Korean Journal of Organic Agriculture
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• v.23 no.4
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• pp.975-985
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• 2015

The susceptibility of the twospotted spider mite, Tetranychus urticae and the predatory mite, Phytoseiulus persimilis to extracts of Melia azedarach, Piper nigrum, Syringa velutina and their mixtures was evaluated in laboratory bioassays. Treatments of mixture 1 and 2 were effective against adult females of T. urticae and yielded 73.3 and 70.7% adulticidal activity at 7 days after treatment, respectively. Treatment of mixture 3 revealed 62.7% adulticidal activity. However, M. azedarach, P. nigrum and S. velutina had lower adulticidal activity than the other treatments. Adult females of T. urticae treated with mixture 1 and 2 produced only 11.1-16.7% as many eggs as control females did. All the plant extracts tested were ineffective to against the eggs of T. urticae. Plant extracts tested had little effect on the survival of P. persimilis adult females. Moreover, reproduction of P. persimilis adult females and eclosion of eggs deposited by treated predators were not seriously affected. Treatment of plant extracts tested showed no toxic effect on P. persimilis eggs and produced 100% hatchability. These results suggest that mixture 1 and 2 might be used for the control of T. urticae, and expected to be promising candidates for use in integrated mite management program with P. persimilis.

• Korean journal of applied entomology
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• v.52 no.4
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• pp.349-356
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• 2013

A set of experiments were conducted to determine the zero temperature and total effective temperature for the summer diapause and post-diapause development of Matsucoccus thunbergianae Miller et Park (Hemiptera: Margarodidae) which infests the Japanese black pine, Pinus thunbergii. The diapausing first instar nymphs were kept in cool storage during three separate times, each starting from May 4th, June 19th, and August 15th of 2002. Cool storage temperatures were 2.5, 5.0, 7.5, 10.0, 12.5 and $15.0^{\circ}C$. The nymphs were chilled for 10, 20, 30 or 40 days in the first two sets of experiments. In the third experiment, nymphs were chilled for 3, 6, 9 or 12 days. Molting into the second instar nymphs was examined every 10 days, starting at 20 days after taken out from the cool storage. Optimum temperature range of the diapause development was between 7.5 and $10^{\circ}C$, where diapause development was completed in 40, 20, and 6 days by the insects chilled from May 4th, June 19th and August 15th, respectively. Comparing the three sets of experiments with different chilling periods, zero temperature for diapause development was calculated as $29^{\circ}C$. Effective temperature for diapause development was 964 degree days, and it was estimated that nymphs completed their diapause development by September 8th in nature. Under natural temperature conditions >50% eclosion into the second instar occurred on November 9th. Zero temperature for post-diapause development was $10^{\circ}C$, and total effective temperature for post-diapause development until the molt into the second instar was 391 degree days.

• Journal of Sericultural and Entomological Science
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• v.15 no.2
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• pp.9-14
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• 1973

In order to find out effects of the generative power of silk worm moth which have been brought up in the high temperature accommodation at their pupa stage. For this specific study, 9 different kinds of male silk worms have been selected as specimen. All those specimen were brought up in the normal temperature at their larvae stage and after the pupation period they have been accommodated in the condition of high temperature for a certain length in accordance with the study programme. Afterwards, those mlae specimen were copulated with Suwon jam 103${\times}$104 which were all brought up in normal conditions. This study was carried out to find the copulation function as well as the ratio of unfertilized eggs(male sterility test). Results of study have been revealed as follows: 1) Although some differences were observed, male pura which have been brought up in the condition of high temperature shown the low rate of unfertilized eggs rather than those were brought up in the normal conpition. 2) In this group the eclosion(emergency) has been found to be poor rather, than those specimen brought up in normal conditions. 3) The copulation function of Moran, Daedong, J124 and C108 specimen were found to be poor than those of Suwon jam. 4) Fertility rate of Moran, Daedong, J124 and C108 was found to be around 65%. This figure is rather lower than what we normally expect. 5) Unfertilized egg ratio of Moran, Daedong and C108 were found to be around 20% if they were brought up in the condition of high temperature for one day from the time of pupation: 40% at 2 days, and 70% at 3 days duration. More than 3 days treatment has shown no progress in the unfertilized egg ratio. 6) One day's treatment for the pupa at the later stage has shown the unfertilized egg ratio of about 10%; 20% at 2 day's treatment, 35% at 3 day's treatment, 40-60% at 4 day's treatment, more than 60% at 5 day's treatment, and the 70% of fertilized egg ratio was only observed when the treatment days come to 7 days. It was understood that the unfertilized egg ratio was high at the antepupa stage rather than that of post-pupa stage. 7) According to the result of observation the sperm in copulatory pouch and seminal receptacle out of the normal female silk worm which have been copulated with the male brought up in the condition of high temperature at their moth stage. The reproduction system found in the control zone has been found to be normal and the sperm is amountful and active in motion while the sperm found in the treatment to be limited in amount and slow in motion. The observation was made within 5 hours from the copulation. 8) According to the result of observation of sperm of seminal receptacles of the female silkworm moth, and according to that observation of sperm in the seminal receptacle in female silkworm moth, the amount of sperm and mobility in the female moth brought up in high temperature were poor comparing that were brought up in normal temperature zone. Some of them are even found to be no trace of such. 9) Appearance and mosle of the copulatory organ of the male silkworm moth was found to be no anatomical change. 10) Testis of the later pupa stage which was brought up in the high temperature was found to be almost net developed to anucleate sperm and they are degenerated at stage of between maturation division and sperm abnormal stage. Mean time at control zone, the formation of anucleate sperm was already observed.

• Korean Journal of Environmental Biology
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• v.26 no.3
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• pp.129-137
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• 2008

Alien apple snails (Pomacea canaliculata, Pomacea insularus) used in environmentally-friendly agriculture are different from indigenous snails found in Korea. Due to high herbicidal effects and cost-effectiveness, the number of farmers using the snails has been growing every year since 2000. Moreover, in 2008, because of the outbreaks of avian influenza throughout the country from March to May, 2008, central and local governments recommended the use of alien apple snails in agriculture as an alternative to the ducks-oriented environmentally-friendly agriculture. Therefore, it is expected that the use of alien apple snails in agriculture should be expanded in a near future. Since alien apple snails lay eggs with 95.8% of eclosion rate, they are considered to be potential pests unlike indigenous snails. In addition, Japan, Taiwan and most of the southeast Asian countries had already experienced severe ecological and agricultural damage by the alien apple snails. Subsequently, International Union for Conservation of Nature and Natural Resources (IUCN) designated P. canaliculata as one of "the 100 of the world's worst invasive alien species". It seems highly likely that the alien apple snails in Korea pose a potential threat to conservation of ecosystem and biodiversity since the snails were either found or invaded into the natural environments in some regions of Gangwon-Do and southern parts of Korean Peninsula. However, just recently, agricultural authorities and farmers using alien apple snails in agriculture opposed a proposition of designating the alien apple snails as an ecosystem-disturbing animal described by the Wildlife Protection Act. This is because there has been no concrete evidence of the ecological risk imposed by the alien snails up to now in Korea. Subsequently, in this paper, we analysed the ecological and agricultural risks imposed by the alien snails from the studies done in domestic and abroad. In addition, we proposed an urgent need and reasoning for ecological risk management of the alien snails at the national level as well as using the snails in agriculture.