Abstract:

The composition of larch cone and foliage volatiles mainly consist of monoterpenes with mostly αpinene,β-ocimene,β-pinene,laurene,3-carene,β-phellandrene There are only quantitative differences between volatile emission of cone and foliage. However,volatile composition varies significantly at different cone development stages which corresponds to larch cone fly (Strobilomyia spp) development In early May before cone fly laying eggs,there are no dominant volatile components and all six monoterpenes are relative low. From midMay to late May when cone fly oviposition peak occurs,the contents of the six monoterpenes are obviously higher in the cones being laid eggs by cone fly than cones without eggs. We also found that relative quantity of cone volatiles varies greatly among different clones or different trees of the same clone,the same is true with cone damage rate. Lightly damaged cone showed the higher content of laurene and β-phellandrene. While heavily damaged cones showed lower content of the two compounds But the lowest damaged cone group revealed relativly higher content of β-pinene,laurene,3-carene and β-phellandrene. In the foliage volatiles,when relative quantities of the six components are very low,cone damage is low. Cone damage increases as the relative quantities of β-pinene and 3-carene increase.

Key words: Larch, Volatile, Strobilomyia spp., Cone