Spatial distribution of black pine bast scale, Matsucocus thunbergianae (Homoptera: Cocoidea) on crown of Japanese black pine, Pinus thunbergii in Korea

Black pine bast scale, Matsucocus thunbergianae (Homoptera: Cocoidea) is a serious pest of Japanese black pine, Pinus thunbergii in Korea. In Korea, black pine bast scale was firstly found at the pine forest in Goheung, Junnam province in 1963. Black pine bast scale widely spread out southwestern coastal area of Korea since 1963. Although black pine bast scale infestation area was up to 11,404 ha in 2005, there are few studies on it. Thus, distribution of black pine bast scale on Japanese black pine was investigated in Jinju and Namhae, Gyeongnam province from March to June, 2010. There was positive correlation between thickness of branch and black pine bast scale density (r=0.126). That is, density of black pine bast scale was different depending on thickness of branch. Density was higher at the thicker branch representing 5.14 individuals/1.96 cm2 in ƒÓ2.0-2.5 cm branch while 2.41 individuals/1.96 cm2 at ƒÓ0.2-0.5 cm branch. Density was not influenced by position of crown, but influenced by side. That is, there was no difference in density at the lower, middle and upper parts of the same tree. However, density was higher at the reverse side, facing the ground than front side, facing the sun at the same branch (Pr„ t„ <0.0001).