Abstract:

Abstract: GC-MS was used to determine the composition and the amount of the terpene volatiles collected from the infested cones (by Gravitarmata mairgarotana larvae) by means of head space absoption, during the oviposition period of female adult Dioryctria pryeri. Results showed that 6 kinds of terpenes were found in the volatile blends of the infested and uninfested cone-shoots in Chinese Pine ( Pinus tabulaeformis ), and the emitting amount of the terpenes was to some extent different between night and daytime. During the oviposition period the cone-shoot volatiles at night was very important to coneworm adult due to nocturnal trait of the moth. In those time, specific blend of the herbivore-induced cone in Chinese Pine was composed of 1R-(+)-α-pinene,β-myrcene and D-limonene. Measurement of electroantennography (EAG) in cones of Chinese Pine and armand pine ( Pinus armandi ) showed that EAG response of D. pryeri to the infested cones was significantly higher than the uninfested cones in Chinese pine, but there was no significant difference in EAG response to the infested and uninfested cones of armand pine. A tropism of both sexes in Y-olfactormeter showed that tropism response of female moth to host volatiles was more active than male moth, and the trend response to CH₂Cl₂ extracts from Chinese pine cones was stronger than that from armand pine cone. Moreover, the volatiles of CH₂Cl₂ extracts of one year old needles and the infested cone in Chinese pine attracted more females than that of the uninfested cone did. A tropism experiment of monoterpene standard compounds showed that α-pinene had an important role in attracting the coneworm moth, and a mixture of 1R-(+)-α-pinene, β-myrcene and D-limonene had strong attracting effect to the moth. Furthermore, the infested cone and its extracts could obviously stimulate female to oviposite. The result suggested that CH₂Cl₂ extracts of the infested cone in Chinese Pine might contain ovipositive stimulants of the female. However, CH₂Cl₂ extracts of the cone in armand pine inhibited the femal to oviposite and therefore, they might contain ovipositive deterrents of the female.

Key words: Key words:Dioryctria pryeri, host selection, oviposition selection, herbivore-duced cone, terpene volatiles