| Bark beetles are the worldwide pests to pines and caused tremendous threat to trees health and ecological environment around the world. The shoot beetles Tomicus minor, Tomicus yunnanensis, and Tomicus brevipilosus have been decimating Yunnan pines(Pinus yunnanensis) for more than 30 years in southwest China, which has caused extensive mortality of Yunnan pines and affected sustainability and healthy development of forestry. Thus far, Tomicus beetles are mainly controlled by removing damaged wood and chemical control. However, those methods are labour-comsumingor not eco-friendly. The aim of this paper is to study the intraspecific and interspecific relationships of three Tomicus species in Pinus yunnanensis and the chemical ecological mechanism, so as to improve the effect of attractants. From May to November in 2013, the shoot-feeding stage, and December to January of the following year, the trunk breeding stage, we had investigated the characteristics of the three bark beetle species these two stages in Jianshui county, Ninger county and Anning city in Yunnan Province. In the meantime, the volatiles were collected from the hindguts of three bark beetle species, and shoots and trunks which were helth or damaged by the three bark beetle species. The quantitative and qualitative analysis of the volatiles were done by using gas chromatography(GC) and gas chromatography and mass spectrometry(GC-MS). According to the chemical analysis, indoor and outdoor bioassy, we had improved attractants to different bark beetle species and sexes. The results were showed in the following.(1) There were no significant difference among four different direction of T. minor damaged shoots, while P. yunnanensis preferd East and West direction shoots of pine tree. Diameter of entrance hole of T. yunnanensis was the biggest and that of was T. brevipilosus was the smallest. The entrance hole of T. yunnanensis was the longest away from apical bud and that of T. minor was the shortest. The diameter of entrance hole and distance between entrance hole and tops of T. minor had no significant correlation, but that of T. yunnanensis and T. brevipilosus had highly significant correlation.During trunk breeding stage, T. minor distributed in the lower part of trees, T. yunnanensis distributed in the whole trees in Jianshui county. However, T. minor distributed in the whole trees and T. yunnanensis distributed in the upper part of trees in Yuxi city. In Anning city, T. minor mainly distributed in the lower part of trees, T. yunnanensis mainly distributed in the upper part of trees and T. brevipilosus distributed in the whole trees. That indicated the distribution of the three Tomicus species in pine trees varied in accordence with the quantity and ratio of the species in different sites.(2) During shoot-feeding stage, T. minor and T. yunnanensis had stronger attraction to volatiles which collected from shoots damaged by the same beetle species and sex than to volatiles collected from other damaged shoots. T. brevipilosus not only had strong attraction to volatiles collected from shoots damaged by its own species and sex, but also had attraction to volatiles collected from shoots damaged by T. minor and T. yunnanensis. Meanwhile, the three beetle species showed strong attraction to volatiles collected from its own hindguts, as well as certain degree of attraction to volatiles from each other hindguts. Although the chemical components of volatiles collected from damaged shoots and hindguts of T. brevipilosus in P. yunnanensis and P. kesiya were different, different hosts had not affected the behavioral responses of T. brevipilosus.During trunk breeding phase, all three speciea had strongest attraction to volatiles which collected from trunks damaged by their own species and at same time T. minor and T. yunnanensis also had atrraction to that collected from other two beetle species.. In addition, the three beetle species had strongest attraction to volatiles collected from hindguts of their own species and also had attraction to that from other two species. That indicated semiochemicals from hosts and hindguts of the three Tomicus had important function to the three beetle species.(3) The content of volatiles from shoots which damaged by male T. minor had increased in compared with the content of volatile from healthy shoots, including(+)-Camphene, γ-terpinene,(-)-Limonene, cis-verbenol, trans-verbenol, myrtenol, caryophyllene, thujopsene and cuparene. The content of other volatiles had reduced. Nevertheless, all the content of volatile from shoots which damaged by female T. minor had reduced.The content of volatiles from shoots which damaged by male T. yunnanensis had changed a little in compared with the content of volatile from undamaged shoots, that were(+)-Camphene, γ-terpinene, cis-verbenol, trans-verbenol and myrtenol. The content of other volatiles had reduced. The increased content of volatiles from shoots which damaged by female T. yunnanensis were Myrcene 、 3-Carene 、 γ-terpinene 、 cis-verbenol 、 trans-verbenol 、Myrtenol and Caryophyllene, but the others had reduced.The were no significant changes of the content of myrcene, γ-terpinene,(-)-Limonene, myrtenol and caryophyllene between the the shoots which damaged by male T. brevipilosus in compared with that from healthy shoots, The content of(+)-Limonene, cis-verbenol and trans-verbenol had increased and the others had reduced. The content of volatiles from shoots damaged by female T. brevipilosus had reduced but(+)-Camphene and 3-Carene had on significant change.(4) The results of bioassay, chemical analysis and field trapping test indicated that during the shoot-feeding stage, S-α-pinene, β-pinene, trans-verbenol and myrtenol had strong attraction to male T. minor. β-pinene,3-Carene,trans-verbenol and myrtenol had strong attraction to female T. minor. 3-Carene and myrtenol had strong attraction to male T. yunnanensis. S-α-pinene,trans-verbenol and myrtenol had strong attraction to female T. yunnanensis.(+)-Camphene, 3-Carene, cis-verbenol, trans-verbenol and myrtenol had strong attraction to male T. brevipilosus. S-α-pinene, γ-terpinene, trans-verbenol and myrtenol had strong attraction to female T. brevipilosus.During trunk breeding stage, S-α-pinene,3-Carene,trans-verbenol and myrtenol had strong attraction to male T. minor, while S-α-pinene,β-pinene,3-Carene,trans-verbenol and myrtenol to female T. minor. S-α-pinene,3-Carene,cis-verbenol,trans-verbenol and myrtenol had strong attraction to male T. yunnanensis while S-α-pinene,cis-verbenol,trans-verbenol and myrtenol to female T. yunnanensis. S-α-pinene,β-pinene,Myrcene,3-Carene,cis-verbenol,trans-verbenol and myrtenol had strong attraction to both sexes of T. brevipilosus.(5) Artificial attractants 1, 2, 3, 4, 5 and 6 had optimal attraction effect to male and female T. minor, male and female T. yunnanensis, male and female T. brevipilosus respectively. In addition, attractants No. 1 had attracting effect to both sexes of T. minor. It can be concluded that the semiochemicals which had important roles to the three beetle species differed in components and contents. There still had same ingredients which had attractive action to both sexes of the same beetle species. So these semiochemicals had effected the intraspecific and interspecific relationships of three Tomicus species in Yunnan Province. |
PDF Full Text Request