솔잎혹파리 耐虫性 品種 育性에 關한 硏究 Ⅰ. 耐虫性 選拔木의 虫廮形成度 및 含有 Monoterpene의 組成

Breeding of Varieties of Pines Resistant to Pine Gall Midge (Thecodiplosis japonensis Uchida et Inouye) Ⅰ. Degree of Gall Formation and Monoterpene Composition of Resistant Trees

Employing 13 resistant and 17 susceptible Japanese black pine (Pinus thunbergii Parl.) trees to pine gall midge (Thecodiplosis japonensis Uchida et Inouye) as sample, observations were made on the needle length, the ratio of gall-formed needles, the number of larva per gall and the weight of larva. And, monoterpenes of the oleoresin of 1-year-old branches, new shoots and needles were analysed by means of gas liquid chromotograph. And, following results were obtained. 1. Oviposition of pine gall midge was also made on the neeldes of resistant trees, but the larvae were mostly dead afterward. 2. The percentage of gall-formed needles in the resistant trees was 2.0, and the number of larva per gall and the weight of 100 larvae in the resistant trees were 640 and 91.4 percent respectively of those in the susceptible trees. 3. No directional differences in monoterpene composition were found in 1-year-old branches and the new shoots of the same trees. 4. The contents of limonene and β-phellandrene were higher and the content of β-pinene was lower in the resistant than in the susceptible trees in the their 1-year-old branches and new shoots. 5. In the needles, the resistant trees showed higher contents of limonene and terpinolene but lower contents of both α-and β-pinene compared to the susceptible trees. 6. In all of the 1-year-old branches, the new shoots and the needles, limonene was always higher and β-pinene was lower in their contents in the resistant trees than in the susceptible trees. Especially the limonene content in the needle was significantly higher in the resistant trees compared to the susceptible trees. It was, therefore, considered that the limonene content in the needle might affect the resistance of the Japanese black pine to the pine gall midge.