솔잎혹파리 耐蟲性 品種 育成에 關한 硏究 Ⅱ. 솔잎혹파리 耐蟲性 Pinus thunbergii의 針葉內 Monoterpene의 季節的 變化

Breeding of Varieties of Pines Resistant to Pine Gall Midge (Thecodiplosis japonensis UCHIDA ET INOUYE) Ⅱ. Seasonal Variation of Needle Monoterpene Composition in Resistant Pinus thunbergii

Employing 7-15 resistant and 8-15 susceptible Japanese black pine (Pinus thunbergii Parl.) trees to pine gall midge (Thecodiplosis japonensis Uchida et Inouye) as samples, needle monoterpenes were analysed by GLC in January and June, and observation was made on the oviposition preference. Following results were obtained. 1. In January, the resistant trees showed higher contents of myrcene, limonene, β-phellandrene and terpinolene but lower contents of α-and β-pinene and camphene compared to the susceptible trees. But in June, α-pinene, camphene, limonene, β-phellandrene and terpinolene were higher and the content of β-pinene and myrcene were lower in the resistant trees than the susceptible trees. 2. The content of limonene was higher by 6.8 percent and the content of β-pinene was lower by 9.2 percent in the resistant trees than in the susceptible trees in June. 3. No preference for oviposition was found between resistant and susceptible trees. But in the resistant trees gall formation rate was quite lower than the susceptible trees. It was considered. therefore, that limonene and β-pinene content in the needle might be used as an indicator of the resistant Japanese black pine to the pine gall midge regardless of season.