Study On The Resistant Mechanism Of Chinese Pine To Red Turpentine Beetle

In order to study the resistant mechanism of Chinese pine (Pinus tabulaeformis) to Red Turpentine Beetle(RTB) (Dendroctonus valens) and the role of the resin and turpentines, damage status in various site conditions were investigated and at the same time the resin were collected in Lingkongshan Forestry Farm, Taiyue Forest Bureau Shanxi province in July,2005.The field investigation showed that damage of pines at sunny slope was heavier than that at shady slope, that at foot of the mountain was heavier than that at top, and that at the middle was lightest. Red Turpentine Beetle mostly likes the pines that has BH 20~40a, the secondly the 40a, and the lastly below 20a. The attack rates of pines after resin collection were higher than that of untouched pines. The analysis of resin contents showed that main monoterpenes were α-pinene, camphene, β-pinene, myrcene and limonene and some times there were 3-carene and α-terpine. Main sesquiterpenes were α-cedrene, longifolene and caryophyllene while diterpenes were thunbergol, Pregn-14-ene, 7-methyl-4b-phenanthrenecarboxylicacid, atis-16-ene, 7-methyl -8-phenanthrenecarboxylic acid, 5-phenanthrenecarboxylic acid, 9-phenanthrenecarboxylic acid, methyl-abietate, 7 -phenanthrenecarboxylic acid .Among three pine age grades, total monoterpene content of 20~40a was highest, that of 20a was lowest. At different slope direction and slope position the total monoterpene contents were also varied, on the top and shade slope were highest and in the middle and sunny slope were lowest. For various damage levels, the total monoterpene content of healthy pines was highest, followed by previously damaged pines, continuously damaged pines. Attacked three days later by RTB the total monoterpene content decreased.There were no significant differences of the longifolene contents among pine age grades but varied among pines at different slope directions and positions. Previously damaged pines had significant low longifolene content compared with other damage levels.The contents of atis-16-ene were significantly varied among pine age grades. The total diterpene contents varied among different slope directions and positions, of the same slope position that on sunny slope were highest and that at same slope direction middle slope were highest. There were diterpene composition differences among pines of different damage grades, but no significant differences of the total diterpene contents. Attacked three days later by RTB, 7- phenanthrenecarboxylic acid and total diterpene content decreased.In general, there are effects of pine age and site condition to the resistance of Chinesepine to RTB. The most resistant pines are age of 20a. Pines at shade slope and middle slope position have highest resistance to RTB. The terpene composition and content of Chinese pine play a role in its resistance. The results indicate that total content of monoterpenes and diterpenes are correlated with its resistance, and /?-pinene, myrcene and limonene seems important. Others terpenes is uncertain.