【作者】 蔡晓明；

【导师】 陈宗懋；

【作者基本信息】 中国农业科学院 ， 农业昆虫与害虫防治， 2009， 博士

【摘要】 植物挥发物是自然界中普遍存在的化学信息,植物通过改变挥发物的释放调节植物、害虫、天敌三者之间的相互关系,从而影响整个群落的结构和组成。本文研究了未受损茶树、离体茶梢和机械损伤诱导的茶树叶片挥发物的释放规律;茶丽纹象甲Myllocerinus aurolineatus Voss、假眼小绿叶蝉Empoasca vitis、茶尺蠖Ectropis obliqua危害诱导的茶树挥发物的释放规律;并通过电子鼻(zNoseTM)在田间监测了茶尺蠖诱导茶树挥发物的季节变化。未受损茶树挥发物中包含6种挥发性物质。这6种挥发物在一天的中午(12:00-13:00)时释放量最大,在黎明前(04:00-05:00)释放量最低。从离体茶梢挥发物中鉴定出19种物质。在不同的采摘后时间,茶梢挥发物不同。采摘后0.5h,离体茶梢挥发物中主要成分是绿叶性气味物质(Z)-3-hexenyl acetate,其相对含量为81.31%;而采摘后7.5h,离体茶梢挥发物中主要成分为萜烯类物质(E)-β-ocimene、DMNT,其相对含量分别为52.09、27.80%。通过SPME-GC-MS测定发现,茶树叶片经机械损伤后均可立即释放5种绿叶性气味物质。其中(Z)-3-hexenal、(Z)-3-hexenol或(Z)-3-hexenyl acetate的释放量较大。此外,机械损伤还可诱导茶树叶片新产生少量的非绿叶性气味物质。通过zNoseTM研究发现,机械损伤的程度越大,(Z)-3-hexenal、(Z)-3-hexenol、(Z)-3-hexenyl acetate等三种绿叶性气味物质的释放量越大;新、老叶片在遭受同样的机械损伤后,这三种绿叶性气味物质的释放不完全相同;机械损伤后,这三种绿叶性气味物质释放高峰的出现时间不同。茶丽纹象甲、假眼小绿叶蝉、茶尺蠖等三种茶树害虫危害后,茶树可释放不同的虫害诱导挥发物。茶丽纹象甲成虫取食诱导的茶树挥发物中包括:4种组成型化合物,47种新形成型化合物;茶尺蠖幼虫取食诱导的茶树挥发物中包括:4种组成型化合物,51种新形成型化合物;假眼小绿叶蝉成虫危害诱导的茶树挥发物中包括:2种组成型化合物,1种诱发型化合物,29种新形成型化合物。三种害虫危害后,茶树挥发物中大多数新形成型化合物具普遍性,极少数具有一定程度的专一性。β-bisabolene仅可被茶尺蠖幼虫取食诱导产生,TMTT仅可被假眼小绿叶蝉成虫危害诱导产生,γ-terpinene可被茶丽纹象甲成虫和假眼小绿叶蝉成虫危害诱导产生。这些专一性物质的释放具有一定的稳定性(在所试的任一虫口密度下均可产生),但它们的释放量均较小(相对含量<1%)。三种害虫危害后,茶树挥发物的差异还表现在不同物质的释放量上。茶尺蠖1龄幼虫持续取食28h后,benzyl nitrile的释放量最大;茶丽纹象甲成虫持续取食28h后,(E)-β-ocimene的释放量最大;假眼小绿叶蝉成虫持续危害后,茶树挥发物主要由(E)-β-ocimene、DMNT、(E,E)-α-farnesene等三种物质组成。虫口密度、危害时间以及危害方式能够影响虫害诱导茶树挥发物的释放。虫口密度越大,虫害诱导茶树挥发物的释放量也越大,同时其中包含的新形成型化合物的种类也越多。在一定范围内危害时间越长,诱导产生的挥发物释放量也越大。仅被危害过6h的茶树,在虫害后第二天其挥发物的释放量显著低于被持续危害的茶树。与咀嚼式口器害虫茶尺蠖、茶丽纹象甲相比,刺吸式口器害虫假眼小绿叶蝉危害后,茶树释放的组成型化合物、新形成型化合物的种类都较少。因茶尺蠖低龄幼虫、高龄幼虫口器大小不同而造成的危害方式差异也能对其诱导的茶树挥发物的释放产生影响,茶尺蠖3龄幼虫取食诱导产生的茶树挥发物的释放量以及其中新形成型物质的种类都较茶尺蠖1龄幼虫取食诱导产生的少。不同虫口密度的三种害虫持续危害时,茶树挥发物的释放展现出相似的时间动态变化。组成型化合物可在接虫后立刻产生,而后随着危害时间的延长,新形成型化合物不断出现,挥发物的释放量不断增加。至接虫后24-28h,茶树挥发物的释放达到一种相对稳定的状态。此后大多数新形成型化合物的释放呈现出昼高夜低的释放规律。与之相反,茶丽纹象甲成虫取食诱导产生的1,3,8-p-menthatriene,茶尺蠖1龄幼虫取食诱导产生的(E)-β-ocimene则呈现出明显的夜高昼低释放规律;三种害虫危害诱导产生的indole在达到释放顶峰后,其释放量会随着危害时间的延长而逐步减少;还有少数物质的释放量可随危害时间的延长而增加。与被低虫口密度持续危害过的茶树相比,去除害虫后被高虫口密度持续危害过的茶树,其挥发物中新形成型化合物停止释放得较晚。在室内用GC-MS与zNoseTM对茶尺蠖幼虫取食诱导茶树挥发物进行了比较分析,结果表明:两者对茶尺蠖幼虫取食诱导的茶树挥发物的定性分析结果差别不大,但两者的定量分析结果有一定差异。在田间利用zNoseTM监测了茶尺蠖诱导茶树挥发物的季节变化。结果显示大多数物质在春季的释放量显著高于秋季,而(E, E)-α-farnesene则相反。本研究深入探明了茶丽纹象甲、假眼小绿叶蝉、茶尺蠖等三种茶树害虫诱导的茶树挥发物的组成、含量、释放时间动态,以及其释放的影响因素。这对进一步探明茶树、害虫、天敌三者之间的相互关系具有重要的参考价值。更多还原

【Abstract】 Plant volatiles are the chemical information existing popularly in nature, and could mediate the tritrophic plant-herbivore-carnivore interaction and influenc the structure and composition of insect community in the ecosystem. In this research, the volatiles of healthy tea plants, intact tea shoots and mechanically damaged tea leaves were analyzed, the emission of volatiles emitted from tea plants damaged by tea weevil (Myllocerinus aurolineatus), tea leafhopper (Empoasca vitis) and tea geometrid (Ectropis oblique) were investigated, and the seasonal variation of volatiles emitted from tea plant damaged by E. obliqua was monitored by electronic nose (zNoseTM) in situ under field condition..The volatiles emitted from healthy tea plants were composed of 6 compounds. Healthy tea plants emitted much high levels of these volatile compounds at noon (12:00-13:00), and extremely low levels before the dawn (04:00-05:00). The volatiles emitted from intact tea shoots were composed of 19 compounds. But it changed at different times when tea shoots were plucked. The relative content of (Z)-3-hexenyl acetate was 81.31% at 0.5h after tea shoots were plucked, and the relative contents of (E)-β-ocimene and DMNT were 52.09, 27.80% respectively at 7.5h after tea shoots were plucked.It was found with SPME-GC-MS method that five green leaf volatiles were emitted immediately from tea leaves after mechanical damage, and (Z)-3-hexenal, (Z)-3-hexenol or (Z)-3-hexenyl acetate were the major volatiles emitted from mechanically wounded tea leaves. However, some novel compounds were induced by mechanical damage also. A further investigation by using zNoseTM showed that more mechanical damage level resulted in the more emission of (Z)-3-hexenal, (Z)-3-hexenol and (Z)-3-hexenyl acetate emitted from young leaves; the emission of them produced by the same mechanical damage on old leaves and young leaves was different; and the emission peak of them appeared at different time after mechanical damage.A different volatiles could be emitted from the plants damaged by the different tea pststs including M. aurolineatus, E. vitis and E. oblique. The volatiles induced by M. aurolineatus adults composed of 4 constitutional compounds and 47 novel compounds; the volatiles induced by E. vitis adults composed of 2 constitutional compounds, 1 induced compound and 29 novel compounds; the volatiles induced by E. oblique larvae composed of 4 constitutional compounds and 53 novel compounds. Most of the novel compounds induced by three herbivore species were similar, however there were some specific novel compounds induced respectively by different pests.β-bisabolene only induced by the larvae of E. oblique, TMTT only induced by E. vitis adults, andγ-terpinene induced by M. aurolineatus adults and E. vitis adults. These specific novel volatile compounds steadily induced by these three herbivore species under any densities tested, and their emission amounts were relatively low (the relative contents were less than 1%). However, there was great difference in quantity of the tea plants volatiles induced by these three herbivore species. The emission of benzyl nitrile was the highest from tea plants continuously infested by first-instar larvae of E. obliqua for 28h; the emission of (E)-β-ocimene was the highest from tea plants continuously infested by M. aurolineatus adults for 28h; and the volatile emitted from tea plants damaged by E. vitis adults continuously were mainly made up of (E)-β-ocimene, DMNT and (E,E)-α-farnesene.Density and the damaging period as well as the feeding style influenced the emission of herbivore-induced tea plants volatiles. The higher density of herbivore induced the more abundant volatiles in both quantity and quality. The damaging period influenced the liberated amounts of volatiles from the tea plant. Under the damage by tea pest for 6 hrs, the emission of inducible volatiles emitted from damaged tea plants on the next day was significantly lower than those tea plants damaged continuously. With regarding the damaging type, investigation showed that the constitutional compounds and novel compounds induced by the insects with chewing mouthparts (M. aurolineatus and E. oblique) were more than those induced by the insects with piercing-sucking mouthparts (E. vitis). Beacause of the difference in the size of mouthparts, the different type of damage caused by the different instars of E. oblique influnced the emission of tea plants volatiles. The volatiles induced by first-instar larvae of E. obliqua were more abundant in both quantity and quality than those damaged by the third-instar larvae.Investigated showed that the emission dynamics of volatiles emitted from tea plants damaged by different diensities of three herbivore species were similar. Constitutional compounds were emitted from tea plants immediately after insects inoculated. As damage proceeded,abundant volatiles were emitted from damaged tea plants. The emission of volatiles reached a relatively stable state at 24-28h after insects inoculated. Since then, the emission of most novel compounds followed diurnal cycles with increased emission during light period and reduced emission during darkness. However, 1,3,8-p-menthatriene induced by M. aurolineatus adults and (E)-β-ocimene induced by first-instar larvae of E. oblique were emitted in an opposite diurnal fashion, the emission of indole induced by three herbivore species was slowly reduced after reached the emission peak, and the emission of other individual compounds slowly increased as damage proceeded. After insects removed from continuously damaged tea plants, the emission of the novel compounds induced by high density of insect ceased later than those induced by low density of insect.In laboratory the tea plants volatiles induced by E. oblique was analyzed synchronously with GC-MS and zNoseTM. The qualitative analysis with GC-MS or zNoseTM showed similar results, but there was different in the quantity analysis with GC-MS and zNoseTM. Under field condition, the seasonal variation of voaltiles emitted from tea plant damaged by E. Obliqua larvae was monitored with zNoseTM in situ. The emission of most novel compounds were significant higher in spring than in autumn, but the emission of (E, E)-α-farnesene in spring were significant lower than in autumn.In summary, the components, contents, emission dynamics, and the influencing factors on emission of volatiles emitted from tea plants damaged by M. aurolineatus, E. vitis and E. oblique were investigated in this study. These results offered an important reference for studying the tritrophic tea plant- herbivore-carnivore interaction.更多还原