• Journal of Korean Society of Forest Science
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• v.83 no.4
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• pp.450-459
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• 1994

The damage by the black-tipped sawfly, Acantholyda posticalis posticalis Matsumura, has been increasing at several locations in central part of the Korean peninsula. This study was undertaken at selected plots in Kapyung-gun, Kyunggi Province and Hongchon-gun, Kangwon Province from 1984 to 1987. The purpose of this study was to provide basic information for integrated control of this pest and to determine the economic threshold by investigating the pest host interactions with special reference to damage analysis. The results obtained were as follows ; 1. The damage was more severe at upper part than at lower part of the crown. The vertical distribution of dry weight of damaged trees above ground showed L-type distribution, whereas that of healthy trees showed C-type distribution. 2. The needle loss by sawfly reduced both of height and the diameter growth of the main stem. The growth reduction occurs when the needle loss is 50% or higher. About 10% of tree growth was reduced at 50% of needle loss. 3. The reduction of diameter growth was more severe at upper part than at lower part of the main stem. 4. Volume growth was reduced when more than 50% of the needles were damaged after three years of the sawfly infestation. Reductions of total volume increment at the levels 70% and 90% of needle damage were 9% and 20%, respectively.

• Journal of Korean Society of Forest Science
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• v.89 no.5
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• pp.630-633
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• 2000

The damage by the black-tipped sawfly, Acantholyda posticalis posticalis, has been increasing all over the area of Korean pine(Pinus koraiensis)stands in Korean peninsula. This study was conducted to provide basic information for the management and control of this pest by investigating the feeding quantity of pine needles during the larval stage. The results were summarized as follows : The total needles damaged in the larval stage of the black-tipped sawfly were 9,584mm in length on an average and those of female and male were 11,774mm and 7,394mm, respectively. The total length ingested actually was 7,797mm and it was equivalent to 81.4% of the total length damaged. Early larval stage showed a little feeding and it was equivalent to 17% of total quantity. On the contrary, the feeding quantity in late larval stages of fourth and fifth instars amounted to 83%. The number of the frass excreted per larva was about 1,160, and the difference between male and female was not showed, whereas it showed remarkable difference among larval instars.

• Journal of Korean Society of Forest Science
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• v.83 no.4
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• pp.498-504
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• 1994

The damage by the black-tipped sawfly, Acantholyda posticalis posticalis Matsumura, has been incheasing at several locations in central part of the Korean peninsula. This study was undertaken at selected plots in locality of Kapyung-gun. Kyunggi Province from 1984 through 1987. The purpose of this study was to provide basic information for integrated control of this pest and to determine the economic threshold by investigating the pest-host interactions with special reference to damage analysis. The results obtained were as follows ; 1. One year old cone formation began to be reduced when 30-40% of the needles were destroyed. With 70% of defoliation, few cones were produced. 2. Number of two year old cone formation and amount of cones began to be reduced when 61-70% of the needles were destroyed ; economic threshold of the defoliation rate retarding the seed production was 51%. 3. Growth of the trees was significantly reduced when more than 50% of the needles were destroyed, and cone production began to be retarded at 30-40% of defoliation. Therefore, it was determined that the economic thresholds requiring the control practices to keep normal tree growth and cone production from being reduced were 50% and 30%, respectively.

• Journal of Korean Society of Forest Science
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• v.87 no.3
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• pp.328-333
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• 1998

To obtain basic information for establishing a pest control strategy for insect pest management system, changes in the population densities of the black-tipped sawfly(Acantholyda posticalis posticalis Matsumura) and damage patterns in tree growth were investigated in national forests in Hoigok-ri, Kapyung-gun, Kyunggi-do, where the pest control measures were taken. The results obtained were as follows ; 1. The larval density in the soil of the forests where the insecticides were applied have been kept below economic threshold for about 7 years. The density was the highest in the middle of slopes and similar to the level of the early stage of the insect outbreak. 2. After the pest control by insecticides, reduction in tree height and diameter growth lasted for 2-3 years in trees defoliated by over 70%. 3. The diameter growth of the trees damaged by black-tipped sawfly recovered faster in upper stem than in the lower. 4. volume growth of the trees defoliated over 70% by the insect decreased for three to four years. The volume loss of trees defoliated by 70% and 90% was 19.6% and 54.0%, respectively. 5. Maintaining the rate of defoliation below 50%, which is the economic threshold, by chemical control measures had an effect of reducing the tree volume loss by $40m^2/ha$ as compared with a stand defoliated by 90%.

• Korean journal of applied entomology
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• v.35 no.3
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• pp.221-227
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• 1996

Four strains of Beauveria bassiana F101, F587, F9 and FJ8, were received from Forestry Research Institute,Seoul. The strain, B. bassiana F101, was the most active in the enzymatic activity and spore production. Whenspores of B. bassiana FlOl were sprayed on the female larva of the black tipped sawfly with various concentrationsof 6 xl 0'~-10s~p ores/ml, insects started to die from 5-7 days, and were covered with mycelia andspores in 24-28 days at 25"C, while the insect did not show visible symptoms even after 50 days at 4'C. Theinsect injected with 5 pl of spore solution (3X l0'~-10s~p oreslml) died within 30-98 and 38-218 hours at25$^{\circ}$C and 4"C, respectively. About 3 days (60 hours) after the injection with a concentration of 3 x lo9 spores1ml, at the point of the insect's death, lots of proteins started to disappear '||'&'||' the hemolymph, fat body and carcaseat 25'C. Esterase activity in the tissues was gone suddenly after that time. Six days after the spray, manyprotein and esterase bands were lost in the hemolymph, but not those in the fat body and carcase. When thefungi growing in the host were exposed in the air, they put energy for spore production, while numerous longand thin mycelia branched out from the host body in the soil.e host body in the soil.