• Korean Journal of Microbiology
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• v.45 no.4
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• pp.332-338
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• 2009

A xylan-decomposing bacterium, HY-20, was isolated from the gut of a honeybee, Apis mellifera, and identified as Bacillus sp. The extracellular GH11 xylanase (XylP) gene (687-bp) of strain HY-20 encoded a protein of 228 amino acids with a deduced molecular mass of 25,522 Da and a calculated pI of 9.33. The primary structure of XylP was 97% identical to that of B. pumilus xylanase (GenBank accession no.: AY526092) that has not been characterized yet. The recombinant His-tagged enzyme (rXylP) overexpressed in Escherichia coli BL21 harboring pET-28a(+)/xylP was purified to electrophoretic homogeneity by cation exchange and gel permeation chromatographies. The purified enzyme exhibited the highest catalytic activity toward birchwood xylan at pH 6.5 and $50^{\circ}C$ and retained approximately 50% of its original activity when pre-incubated at $55^{\circ}C$ for 15 min. The recombinant enzyme was completely inactivated by $Hg^{2+}$ (1 mM) and N-bromosuccinimide (5 mM), while its activity was slightly stimulated by approximately 10% in the presence of $Mn^{2+}$ (1 mM), $Fe^{2+}$ (1 mM), and sodium azide (5 mM). rXylP was able to efficiently degrade various polymeric xylose-based substrates but PNP-sugar derivatives and glucose-based polymers were not susceptible to the enzyme.

• Korean Journal of Environment and Ecology
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• v.35 no.6
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• pp.621-631
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• 2021

The purpose of this study is to survey and analyze acorn production and characteristics of the Quercus acuta Thunb. according to the need for information on seed supply and seedling cultivation during the restoration of warm broad-leaved forests. For the survey, a total of 30 seed traps with a surface area of 1 m² were set up, 3 in each of 10 quadrats (8 in Wando, 1 in Haenam, and 1 in Jindo). The acorns that fell in the seed trap at the end of each month were collected from August to December each year between 2013 to 2016. The collected acorns were then classified into sound, damaged, decayed, or empty grade, and the number of acorns produced was calculated. In the case of sound acorns, acorn traits, such as length, diameter and weight of acorns without cupule, were measured. Duncan's multiple tests of acorn production and characteristics were conducted for comparative analysis of the annual average values with the values by year, stand, month, and treatment plot. The annual number of acorn dropped into the seed traps in each quadrat from 2013 to 2016 was 5-350 acorns/3 m² in 2013, 17-551 acorns/3 m² in 2014, 5-454 acorns/3 m² in 2015, and 14-705 acorns/3 m² in 2016. There was a large difference in acorn production between the quadrats, presumably attributed to the difference in the amount of light received due to the density of trees in the square. Annual acorn production per area was 335,000 acorns/ha in 2013, 932,000 acorns/ha in 2014, 556,000 acorns/ha in 2015, and 1,037,000 acorns/ha in 2016. That was a sharp variation of acorn production in the two-year cycle. As the fluctuation in the production of Q. acuta showed simultaneity between stands, it is judged that Quercus acuta Thunb. had a clear cycle of fruitfulness and fruitiness between forest objects. September showed the biggest amount of fallen acorns and largest damage from insect pests, indicating that preventing early fall of acorns could increase the fruiting period and enable mass production of sound acorns. There was no significant difference between annual average acorn length in each region. In the case of the acorn diameter and weight, the average values of acorns from Haenam were significantly higher than those from Wando and Jindo. There was no significant difference in the average annual acorn characteristics by month, and the average annual acorn length, diameter, and weight in November were 19.72mm, 12.23mm, and 1.64g, respectively, the highest between August and November.

• The Korean Journal of Pesticide Science
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• v.13 no.3
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• pp.190-196
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• 2009

The residues of abamectin 1.8% EC, resisted for control of pine wood nematode, Bursaphelenchus xylophilus in pine tree were surveyed in tissue of Pinus thunbergii and P. koraiensis after injection of a liquid formulation. Limits of detection of abamectin in tissue of P. thunbergii were $0.05\;mg\;kg^{-1}$ and mean recoveries at $0.5\;mg\;kg^{-1}$ trunk injection were 90.9% and 93.1% respectively in stem and trunk of P. thunbergii. Abamectin 1.8% EC, trunk injected in 15 m height P. thunbergii were detected in all stem (edible part of carrier insect of pine wood nematode, Monochamus alternatus) from 0.29 to $0.73\;mg\;kg^{-1}$ after 150 days injection. Amount of residue of abamectin 1.8% EC in 12.6 cm mean breast height diameter (DBH) P. thunbergii were variable depending on individual trees in natural forest. Amount of residues in lower and middle part of trunk were reduced with the passage of the injection time. In upper part of trunk were detected $1.84\;mg\;kg^{-1}$ on 30 days after injection however $0.65\;mg\;kg^{-1}$ on 15 days after injection and under detection limit on 100 and 180 days after injection in P. thunbergii. Bottom and middle parts of crown were detected $0.183\;mg\;kg^{-1}$ and $0.173\;mg\;kg^{-1}$ respectively on 180 days after injection in P. thunbergii. Mean residues of abamectin in crown and trunk were $0.80\;mg\;kg^{-1}$ and $0.30\;mg\;kg^{-1}$ on 170 days after trunk injection in 20 cm DBH and 9 m height P. koraiensis. Mean residues of abamectin in crown and trunk were $0.67\;mg\;kg^{-1}$ and $0.36\;mg\;kg^{-1}$ on 170 days after trunk injection in 15 cm DBH and 6 m height P. koraiensis.

• Korean journal of applied entomology
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• v.56 no.3
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• pp.301-308
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• 2017

Locusts, Locusta migratoria (Orthoptera: Acrididae) are periodical unpredictable agricultural pests worldwide and cause serious damage to crop production; however, little consideration has been given to the management of this pest. Herein, we constructed a locust-pathogenic fungal library and confirmed that some fungi could be used as resources for locust management. First, the entomopathogenic fungi were collected from sampled soils using a Tenebrio molitor-based baiting system. For the locust assay, a locust colony was obtained from the National Institute of Agricultural Science and Technology. A total of 34 entomopathogenic fungal granules, which were produced by solid cultures, were placed in the plastic insect-rearing boxes (2 g/box) and nymphs of locust were contained in the box. In 3-7 days, mycosis was observed on the membranous cuticles of the head, abdomen, and legs of locusts. In particular, Metarhizium anisopliae, M. lepidiotae, and Clonostachys rogersoniana exhibited high virulence against the locust. Given that the 34 isolates could be used in field applications, their conidial production and stability (thermotolerance) were further characterized. In the thermotolerance assay, Paecilomyces and Purpureocillium isolates had higher thermotolerance than the other isolates. Most of the fungal isolates produced ca. >$1{\times}10^8conidia/g$ on millet grain medium. In a greenhouse trial, the granular application of M. anisopliae isolate on the soil surface resulted in 85.7% control efficacy. This work suggests that entomopathogenic fungi in a granular form can be effectively used to control the migratory locust.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.39 no.1
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• pp.37-42
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• 2021

Munseom (Island) is known as the largest native Elaeocarpus sylvestris var. ellipticus in Korea. Recently, disease damage from the E. sylvestris var. ellipticus community has been reported in Munseom. This study was conducted to understand the damage situation and growth characteristics of the E. sylvestris var. ellipticus population in Munseom. The purpose of this study was to evaluate the spontaneous regeneration potential of the community by grasping the characteristics of the population of surviving E. sylvestris var. ellipticus individuals, and to discuss ways to restore native habitats. A total population survey was conducted to determine the distribution status of E. sylvestris var. ellipticus individuals. The field survey carefully recorded the height of tree, DBH, DRH, and growing status, along with GPS location information of the individual. The growth status of E. sylvestris var. ellipticus individuals distributed in Munseom and the characteristics of tree height, DBH, DRH of each individual were analyzed. The total number of E. sylvestris var. ellipticus populations identified in Munseom was 293. The dense E. sylvestris var. ellipticus community reported in 2005 has been identified as being greatly damaged or damaged. In particular, the damage was more serious in mature trees with a height of 6m or more forming the canopy layer in the forest, and it was confirmed that 80.6% of the mature trees died. In the growth characteristics of the old-growth tree, which is an indicator of the health of the forest based on DRH, 75.4% died or the growth condition was found to be poor. In order to restore the native habitat of E. sylvestris var. ellipticus in Munseom, conservation efforts such as pest control, preservation of mature trees, control of the territory of young trees, and reintroduction after ex-situ transplantation etc. are considered necessary.

• Korean journal of applied entomology
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• v.61 no.3
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• pp.399-408
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• 2022

There has been much debate on the morphometric divergence between the recently identified Apis cerana koreana and Apis cerana honey bees. The aim of this study was to obtain phenotypic information that can be used to compare A. c. koreana data with other A. cerana subspecies data from open resources and determine breeding results on the basis of morphometric traits. To differentiate A. c. koreana, we investigated 22 classic morphological characteristics; royal jelly secretion; and the weight of workers, queens, and drones of A. c. koreana bred in Korea. To define the selection results, we used the geometric morphometric method. The artificially selected A. c. koreana secreted significantly more royal jelly (1.18 times) than the naturally selected A. c. koreana, which positively influenced the health of the colonies. These honey bees were identified more clearly with the geometric morphometric method than with the classic morphometric method, which is traditionally used to determine the subspecies. Large trends were noted for A. c. koreana on the basis of our results and literature from the 1980s regarding A. cerana sizes in Korea (tarsal index, length of forewing, and cubital index were measured). The cluster analysis revealed the proximity of A. c. koreana, A. cerana in China, and A. c. indica on the basis of eight classic characters, which, perhaps, relay the origin of the honey bees. The results of this study defined the morphometric responses of A. c. koreana honey bees to geographic isolation, climate change, and selection, which are important to identify, protect, and preserve honey bee stock in Korea.