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        검색결과 539

        145.
        2018.11 구독 인증기관·개인회원 무료
        Although some factors, including season, age, type of estrus (natural estrus vs. induced estrus) and semen type (conventional vs. sexed), affect the conception rate following artificial insemination (AI) in dairy cattle, there is little information about the influence of ovarian characteristics, such as preovulatory follicle (PF) location at estrus, on fertility in dairy cattle. In most breeds of cattle the right ovary appears to function more actively than the left and about sixty percent of pregnancies in dairy cattle occur in the right horn of uterus (Reece and Tuner, 1938). Our study aimed to compare conception rates in dairy cattle between PFs that developed in the left ovary and those that developed in the right ovary at estrus. In this study, we examined the locational effect (left or right ovary) of the preovulatory follicle (PF) on fertility in dairy cattle. In total, 955 artificial inseminations (AI) were analyzed. At AI, PF locations were examined using rectal palpation, and dairy cattle were divided into two groups on their PF locations: (i) the PF located in the left ovary (L-PF); and (ii) the PF located in the right ovary (R-PF). Pregnancy was diagnosed by rectal palpation or ultrasonographic examination 60 days after AI. The conception rate was 38.1% in all dairy cattle. Conception rate was higher in the R-PF (40.8%) than in the L-PF (33.2%). In summary, PF development in the right ovary was associated with increased conception rates in dairy cattle.
        146.
        2018.10 구독 인증기관·개인회원 무료
        Insect-killing fungi have high potential in pest management. A deeper insight into the fungal genes at the whole genome level is necessary to understand the inter-species or intra-species genetic diversity of fungal genes, and to select excellent isolates. In this work, we conducted a whole genome sequencing of Beauveria bassiana (Bb) JEF-007 and characterized pathogenesis-related features and compared with other isolates including Bb ARSEF2860. A large number of Bb JEF-007 genes showed high identity with Bb ARSEF2860, but some genes showed moderate or low identity. The two Bb isolates showed a significant difference in vegetative growth, antibiotic-susceptibility, and virulence against Tenebrio molitor larvae. When highly identical genes between the two Bb isolates were subjected to real-time PCR, their transcription levels were different, particularly in heat shock protein 30 (hsp30) gene which is related to conidial thermotolerance. In several B. bassiana isolates, chitinases and trypsin-like protease genes involved in pathogenesis were highly conserved, but other genes showed noticeable sequence variation within the same species. Given the transcriptional and genetic diversity in B. bassiana, a selection of virulent isolates with industrial advantages is a pre-requisite, and this genetic approach could support the development of excellent biopesticides with intellectual property protection.
        147.
        2018.10 구독 인증기관·개인회원 무료
        In the present study, we make a first report on the complete mitochondrial DNA genome of Leptaulax koreanus, a Korean endemic species, in Passalidae. The mitogenome is 18,730 base pairs with 13 protein coding genes (PCGs), 22 tRNAs, two rRNAs and a 4240 bp long AT-rich region. The overall base composition is 78.4% AT and 21.6% GC. The maximum likelihood analysis inferred that L. koreanus is a sister to other Scarabaeoidea species. The phylogeny suggested that L. koreanus is the basal group of Scarabaeoidea.
        148.
        2018.10 구독 인증기관·개인회원 무료
        This study investigated the fumigant activity of phosphine (PH3) on 2 kinds of mealybug (Pseudococcus longispinus and P. orchidicola (Hemiptera: Pseudococcidae)) adults and nymphs. All of the two mealybugs adults showed higher LCT99 values than nymphs, and P. longispinus showed higher tolerance than P. orchidicola in a 12 L desiccator. The absorption of phosphine on 13 nursery plants showed 12.2~41.5% difference depending on the plant. All of the mealybugs treated with phosphine 2 mg/L in 0.5 m3 fumigation chamber for 4 h showed 100% fumigant activity, except P. longispinus adult (approximately 90% at bottom part). However, when the exposure time was increased to 24 h, all of them showed 100% mortality. In the treatment of 10 m3 container, the 24 h treatment of phosphine showed 100% mortality to P. longispinus and P. orchidicola adults and nymphs. In all the experiments, no phytotoxicity of phosphine observed on 13 plants until 1 month after treatment.
        149.
        2018.10 구독 인증기관·개인회원 무료
        Whitefly (Hemiptera: Aleyrodidae) pests, including the tobacco whitefly, Bemisia tabaci, and the greenhouse whitefly, Trialeurodes vaporariorum, are economically important in agriculture. With the annual growth of the domestic fresh fruit export market, various quarantine treatment methods are being used to export strawberries of better quality. The objective of the present study was to evaluate the effects of gamma rays on the development and reproductive sterility of B. tabaci and T. vaporariorum. In both species, the eggs were completely inhibited from hatching at 50 Gy, and the emergence of 3rd instar nymphs was completely suppressed at 150 Gy. Some adult B. tabaci and T. vaporariorum spawning occurred at 100 Gy and 70 Gy, respectively; however, at these irradiation levels, F1 hatchability was completely inhibited. Dosimetry results showed that the penetrating power of gamma ray in the strawberry-filled box was the lowest at the mid-box position. Therefore, B. tabaci and T. vaporariorum were placed in the middle of the strawberry-filled box and irradiated. A gamma-ray irradiation of 100 Gy suppressed the development and reproduction of eggs and adults in both B. tabaci and T. vaporariorum. However, the development of 3rd instar nymphs was inhibited at 300 Gy for B. tabaci and 200 Gy for T. vaporariorum. Our data suggest that at least 300 Gy should be used for the control of these two types of whitefly for strawberry export.
        150.
        2018.10 구독 인증기관·개인회원 무료
        For the setting of control timing, the number of overwintering eggs on host plants and population density of Metcalfa pruinosa nymphs and adults was surveyed in the three peach orchards. According to a survey of the overwintering eggs density (∅2~3㎝, 20㎝ branches) of M. pruinosa on host plants, 221.8 in Mugunghwa trees, 189.3 Oak trees, and 152.7 Acacia trees, and 57.0 Peach showed the number of eggs laid. Examined peach branches within the 50cm (∅1~5cm) was not found population densities of M. pruinosa nymphs and adults, and it was also very low in the sticky trap. The peak density of the adult was highest at 5.4 per trap on August 7 after being first investigated on July 16 in a string wrap survey, and then decreased. In the peach orchard, it is judged that the control of the M. pruinosa is due to be 20 days after the end of the insect hatching, and that distribution of host plants is more important in the outside region than inside region.
        151.
        2018.10 구독 인증기관·개인회원 무료
        Acaricidal activities of 63 commecial pesticides against the longhorned tick, H. logicornis were investigated. Twenty-two pesticides (4 cabamates, 5 organophophates, 9 pyrethroids, 1 octopamine receptor agonists, 1 diamides, and 1 unknown) against adults H. logicornis showed >80% mortalities after 72 h of treatment. The residual effect of 22 pesticides was investigated at 1, 2, 3, 7, and 10 day intervals on grass for H. logicornis adults and nymphs. Eight and twenty pesticides in H. logicornis adults and nymphs showed >80% acaricidal activity at 3 days after the treatment, respectively. 7 days after the treatment, H. logicornis adults showed <60% acaricidal activity in all pesticides, but 7 pesticides (benfuracarb, gamma cyhalothrin, cypermethrin, lammda cyhalothrin, fenvalerate, cyantraniliprole, fluxametamide) showed >80% acaricidal activity in nymphs. all pesticides exhibited <60% acaricidal activity after 10 days of treatment both adults and mymphs, except benfuracarb showed 96.7% mortality in H. logicornis nymph.
        152.
        2018.10 구독 인증기관·개인회원 무료
        This study investigated number of eggs, hatch rate, toxicities and LT (lethal time) values of Culex pipiens and Aedes albopictus using Aquatain™(Aqua mosquito film). Aquatain™ is a covering agent applied on the surface of water for the control of larva and pupa of mosquito. It forms molecule layer on the surface of the water to lower the surface tension of the water, to prevent flooding of the larva of the mosquito larvae, or to suffocate by obstructing breathing. Cx. pipiens and Ae. albopictus larvae observed 99.9% and 1% larvicidal effect after 24h, respectively. However, both mosquito pupae were showed 100% mortality after 24 h. The AMF™ was treated with three doses (0.5, 1, 2 folds) to observe the LT value in larvae and pupae stages of Cx. pipiens and Ae. albopictus. The LT values of Ae. albopictus pupa was similar regardless of dose, but the LT value of Cx. pipiens pupa decreased as the dose increased. However, Ae. albopictus larvae showed 18.6 folds longer LT90 time than Cx. pipiens larvae. Both species mosquito showed statistically significant differences in the number of eggs laid and hatch rate at recommended dose. Therefore, Aquatain AMF™ may be used to control mosquitoes, although the activity varies depending on the species of mosquito.
        153.
        2018.10 구독 인증기관·개인회원 무료
        The two-spotted spider mite, Tetranychus urticae, is a worldwide agricultural pest that invades a wide range of host crops and rapidly develops resistance to pesticides. T. urticae can be resistant to one acaricide or exhibit multiple resistances or cross resistance to various other acaricides. Acequinocyl inhibits respiration in mitochondria at the ubiquinol oxidation site (Q0) of Complex III of the electron transfer chain. Pyridaben is a METI acaricide that inhibits mitochondrial electron transport at complex I. In this study, we investigated the cross resistance to seven acaricides in acequinocyl- and pyridaben-resistant strain. Furthermore, the frequencies of the I256V and N321S mutations in mitochondrial cytochrome b (cytb) of pyridaben-resistant and fieldcollected strain was analyzed.
        154.
        2018.10 구독 인증기관·개인회원 무료
        The genus Nipponopsyche Yazaki is reported from Korea with an unrecorded species, N. fuscescens Yazaki for the first time. Adult, larva, pupa and genitalia of the species are redescribed with SEM illustrations, and DNA barcode for precise identification of the species is also provided.
        155.
        2018.10 구독 인증기관·개인회원 무료
        흑백알락나비 (Hestina persimilis (Westwood, 1850))는 한반도의 평안남도 이남의 내륙지역에 넓게 분포하고, 국외의 경우 일본, 중국, 히말라야 일대에 서식하는 것으로 알려져 있다. 본 종에 대한 생활사 연구는 김과 서(2011)에 의해 월동유충, 종령, 번데기 등에 대한 일부 보고가 있을 뿐 자세한 생활사에 대한 기록은 전무하다. 본 연구를 통해 한국산 흑백알락나비의 생태적 습성 및 미성숙단계 (알, 유충, 번데기)의 형태적 특징 등 자세한 생활사 정보를 보고하고자 한다.
        156.
        2018.10 구독 인증기관·개인회원 무료
        Encyrtidae, belonging to Chalcidoidea (Hymenoptera), includes about 4,000 species in 460 genera worldwide. Many of the members are very important biological control agents of insect pests such as scale-insects (Hemiptera, Coccoidea). Many species have been relatively well studied in various taxonomic and biological fields because of economical and ecological importance of Encyrtidae. However, Korean encyrtids are poorly studied so far. In this presentation we will introduce the current status of taxonomy and biological characteristics of Encyrtidae. In addition further study plans are also presented.
        157.
        2018.10 구독 인증기관·개인회원 무료
        Two species in Monochamus (Coleoptera: Cerambycidae) are wellknown vector species of the pine wood nematode (PWN) in South Korea. In 2018, the surveys using sentinel logs with two Monochamus species larvae were made from early June to last September in Pinus densiflora forests of Pohang city, South Korea. The experiments were repeated 10 times in order to investigate parasitism patterns of the larval parasitoids of M. saltuarius and M. alternatus. Three plots were chose at interval distance of 20 m (0 m, 20 m, 40 m) from the edge to the center of the forests (i.e. forest depths) in one damage area of the pine wilt disease for each of three different locations. For each time of the exposure ten sentinel logs were hung along the tree heights (i.e. sentinel logs positions) (height: 0 m, 1.8 m, 3.6 m, 5.4 m, 7.2 m). As the results of the surveys six larval parasitoids in total were identified, and most abundant parasitoids were Spathius verustus and Cynopterus flavator. Analyses showed that the parasitism rate on larvae of two Monochamus species was not affected according to forest depth, but the parasitism rate was the highest in the third plot. Also the parasitism rate was the highest at 5.4 m height of a tree. Lastly, parasitisms rate on M. alternatus was higher than that of M. saltuarius.
        158.
        2018.10 구독 인증기관·개인회원 무료
        Beauveria comprises entomopathogenic fungi frequently isolated from insect cadavers, among which Beauveria bassiana is the most widely studied species of entomopathogenic fungal genus for its high potential as a biological pesticide. Even though it has been reported that B. bassiana is a heterogeneous assemblage of strains, little is known about the factors that might drive the genetic diversity among various isolates. In this work, we ought to study the gene diversity of 33 isolates in order to figure out the relationship between their gene diversity and biological features. First, we analyzed gene sequences that are involved in developmental and immunological processes of the fungal isolates and host. Now we are checking whether the gene diversity is related to the genes function, the isolates geographic localization, thermo-tolerance and virulence of the isolates. The obtained results so far showed no correlation between the genetic diversity and the fungal geographic localization. But interestingly, a positive correlation has been obtained between the virulence and the genetic diversity based on the internal transcribed spacers (ITS). Further analyses are aiming to confirm the obtained data and to analyze possible correlations between the genetic diversity and morphological and transcriptional data of the studied isolates. Based on the obtained results, we could much strongly focus on interesting genes which might be related to improving or screening highly virulent fungal agents as biological control agents.
        159.
        2018.10 구독 인증기관·개인회원 무료
        Longhorned tick, Haemaphysalis longicornis (Ixodida: Ixodidae) is one of the vectors of severe fever with thrombocytopenia syndrome virus (SFTSV) in human. The tick occurs in mostly grass fields, and the use of pyrethroid insecticides induced pest resistance and environmental residual toxicity. Particularly the use of chemicals near residential areas where persons live become a big issue, so environmentally safe control agents need to be considered. Here in this work, our interest was given to the selection of highly virulent fungi against H. longicornis. A total of 101 fungal pathogens collected from mountainous areas were assayed by a dipping the nymph stage of ticks into a conidial suspension (1×107conidia/ml). Interestingly among several species, one species showed high virulence and mycosis were observed in 7-15 days. Most of the selected isolates produced a large amount of conidia in Italian millet, rice and millet with thermotolerance at 40-45°C. Based on these results, we selected a couple of isolates with high virulence against H. longicornis and they could be used for the control of the ticks after the set-up of a practical application strategy in fields by optimizing fungal colonization in soil and phyllosphere.
        160.
        2018.10 구독 인증기관·개인회원 무료
        Thrips is one of the serious insect pests in many economic crops, in which general managements rely mainly on chemical insecticides. However, the overuse of chemicals led to the development of insect resistance and environmental residual issues. Therefore, thrips management requires the consideration of alternative strategies which are less harmful to the environment and working on different target points. In this work, we isolated entomopathogenic fungi from soil, and identified them with morphological and molecular biology methods, followed by a preliminary virulence assay against Tenebrio molitor larvae. Selected fungal isolates were adjusted to 1×107 conidia/ml for an indoor virulence assay against thrips adults, and highly virulent isolates were added to a thrip-pathogenic fungal library. Biological characteristics of efficacious isolates were investigated comparing to a previously commercialized fungal isolate. This entomopathogenic fungal library could be used as a valuable resource for developing effective strains to control thrips in agricultural fields.