• Korean Journal of Environment and Ecology
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• v.29 no.4
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• pp.590-598
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• 2015

Despite various control methods for pine wilt disease, the disease has been increasing at an alarming rate every year in Korea. Still there is a lack of research on the problems of the current methods used to curb the disease. One main method to control pine wilt disease is fumigation for eliminating the larva of the pine sawyer beetle (Monochamus alternatus) which is known as the vector insect for pine wilt disease. We surveyed and analyzed the amount of destroyed uninfected trees in the fumigated area by studying 32 survey plots ($100m^2$) in Miryang city. The destroyed trees' crown area was estimated by induced regression between root collar area and crown area of the remaining trees (coniferous tree: $R^2=57.4$, deciduous broad-leaved tree: $R^2=63.8$). According to the analysis results, the infected trees (cut trees) were 18.7% and cut trees which were not infected were 35.5% of the total tree population of the study area on the basis of total crown area. In case of pine trees, 8.4% of uninfected trees were cut off but 62% of uninfected deciduous broad-leaved trees including Quercus spp. were affected and damaged during the fumigation process. Since these broad-leaved trees dominate the sub-canopy layer of the forest, this indiscriminate interruption of broad-leaved trees has the adverse effect of depriving the public benefits such as shadow, a cooler weather, controlling humidity, etc.

• Journal of Korean Society of Forest Science
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• v.110 no.2
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• pp.280-288
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• 2021

Understanding the occurrence characteristics of pine wilt disease (PWD) is essential for determining a suitable strategy to minimize the damage caused by PWD. Thus, in this study, we characterized various environmental conditions, including meteorological factors, geographical factors, and artificial factors influencing the occurrence of PWD. The occurrence data of PWD from May 2016 to April 2018 and spatial data of various environmental factors, including natural and anthropogenic factors, were collected. We evaluated the relative contribution of the environmental variables on the number of dead pine trees by PWD. In this study, among the 17 natural and anthropogenic factors, the factors affecting the occurrence of dead trees by PWD were verified. The results showed that altitude and temperature from May to August, among natural factors, and distance to building and forest road among anthropogenic factors were the most influential factors on the occurrence of PWD.

• Journal of Korean Society of Forest Science
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• v.107 no.4
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• pp.486-496
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• 2018

Pine wilt disease (PWD) in Gyeonggi province was first detected in Gwangju in 2007, and ever since has caused extensive damage. Insect vector and host tree in Gyeonggi province are Monochamus saltuarius and Pinus koraiensis, respectively, which are different from the southern region that consist of Monochamus alternatus and Pinus densiflora. Consequently, spread and mortality characteristics may be different, but our understanding is limited. In this research, we utilized the spatial data of newly infected trees in Gyeonggi province from 2008 to 2015 to analyze how it is related to various environmental and human factors, such as elevation, forest type, and road network. We also analyzed the minimum distance from newly infected tree to last year's closest infected tree to examine the dispersal characteristics based on new outbreak locations. Annual number of newly infected trees rapidly increased from 2008 to 2013, which then stabilized. Number of administrative districts with infected trees was 5 in 2012, 11 in 2013, and 15 in 2014. Most of the infected trees was Pinus koraiensis, with its proportion close to 90% throughout the survey period. Mean distance to newly infected trees dramatically decreased over time, from 4,111 m from 2012 to 2013, to approximately 600 m from 2013 to 2014 and 2014 to 2015. Most new infections occurred in higher elevation over time. Distance to road from newly infected trees continuously increased, suggesting that natural diffusion dispersal is increasingly occurring compared to human-influenced dispersal over time.

• The Plant Pathology Journal
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• v.23 no.2
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• pp.70-75
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• 2007

We conducted an inoculation test using nine open-pollinated families of pine trees to evaluate their susceptibility and mortality in different densities of pine wood nematode. Three-year-old nine open-pollinated pine families were inoculated with Bursaphelenchus xylophilus at levels of 3,000, 5,000, and 7,000 nematodes/seedling in greenhouse. There were no distinct patterns in latent period among three densities of B. xylophilus in all families. Most families showed the first disease symptoms of needle discoloration within 12-15 days after inoculation. However, open-pollinated progenies of Pinus densiflora showed the longest latent period because none of one-year-old needles were wilted until 14 days after inoculation with 5,000 and 7,000 nematodes. One-year-old needles were wilted earlier than current needles in all tested families with all densities of B. xylophilus. Current needles were not wilted until 14 days after inoculation in all seedlings. The mortality of all seedlings rapidly increased from 35 days to 49 days after inoculation, and all died within 80 days except two seedlings. A 3,000 nematodes/100 ${\mu}L$ with sterilized distilled water are enough to screen 3-year-old pine seedlings for resistance to B. xylophilus.

• Journal of Microbiology
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• v.45 no.5
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• pp.394-401
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• 2007

In this study, bacterial communities within the guts of several longicorn beetles were investigated by a culture-dependent method. A total of 142 bacterial strains were isolated from nine species of longicorn beetle, including adults and larvae. A comparison of their partial 16S rRNA gene sequences showed that most of the bacteria constituting the gut communities can typically be found in soil, plants and the intestines of animals, and approximately 10% were proposed as unreported. Phylogenetic analysis demonstrated that the bacterial species comprised 7 phyla, and approximately half were Gammaproteobacteria. Actinobacteria were the second most populous group (19%), followed by Firmicutes (13%) and Alphaproteobacteria (11%). Betaproteobacteria, Flavobacteria, and Acidobacteria were minor constituents. The taxonomic compositions of the isolates were variable according to the species of longicorn beetle. Particularly, an abundance of Actinobacteria existed in Moechotypa diphysis and Mesosa hirsute, which eat broadleaf trees; however, no Actinobacteria were isolated from Corymbia rubra and Monochamus alternatus, which are needle-leaf eaters. Considerable proportions of xylanase and pectinase producing bacteria in the guts of the longicorn beetles implied that the bacteria may play an important role in the digestion of woody diets. Actinobacteria and Gammaproteobacteria were the dominant xylanase producers in the guts of the beetles.

• 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.57 no.3
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• pp.151-160
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• 2018

Anoplophora chinensis and A. glabripennis is classified as important quarantine Cerambycidae beetles worldwide. These beetles cause serious damage on natural host plants and export bonsai trees in Korea. We evaluated efficacy of phosphine fumigant for control of two Cerambycidae beetles in bonsai. In the preliminary test to achieve CT (Concentration x time) values of phosphine to Cerambyicdae beetles larvae, we used Monochamus alternatus of larvae as an alternative insect. A 24 h phosphine fumigation with $2g/m^3$ phophine achieved 100% eggs mortality against Anoplophora chinensis and A. glabripennis. Larva of A. chinensis was also completely controlled when treated for 168-h at same dose desiccator. 100% mortality on larval stage of two beetle species were achieved both in dormancy (January) and vegetative period (February) of bonsai when treated with $2g/m^3$ phosphine. However, phosphine fumigation against vegetative period of Acer palmatum, Carpinus turczaninowii and Malus sieboldii bonsai showed slight phytotoxicity (shorten leaf and flower size and delayed flowering).