茉莉酸诱导桑枝对桑天牛卵啮小蜂的引诱作用及桑枝挥发物组分分析

【目的】探讨茉莉酸诱导的桑树Morus alba枝挥发物对桑天牛卵啮小蜂Aprostocetus prolixus趋性行为的影响,研究桑枝挥发物的动态变化规律,为揭示茉莉酸诱导桑枝产生的间接抗虫作用机理提供理论依据。【方法】本试验利用嗅觉测定仪,研究了不同浓度茉莉酸处理24,48和72 h后的桑枝对桑天牛卵啮小蜂的引诱作用,并采用气相色谱-质谱联用仪(GC/MS)对茉莉酸(1 000μmol/L)处理不同时间后的桑枝挥发物组分进行了分析。【结果】在10μmol/L茉莉酸处理后的不同时间内,桑枝对桑天牛卵啮小蜂均未表现出明显的引诱作用;当茉莉酸浓度为100μmol/L时,桑枝仅在处理48 h后对桑天牛卵啮小蜂具有显著的引诱活性;然而,经1 000μmol/L茉莉酸处理24 h和48h后,桑枝对桑天牛卵啮小蜂的引诱活性明显高于对照(24 h,P0.05;48 h,P0.01),72 h后桑枝的引诱作用消失。Spearman等级相关性分析表明,茉莉酸浓度与桑枝对桑天牛卵啮小蜂的引诱百分率显著正相关(ρ=0.791,P=0.006)。茉莉酸(1 000μmol/L)处理桑枝挥发物组分包括醇类、酯类、萜类物质、芳香族化合物和含氮化合物,其中萜类物质种类最多(13种)。随着处理时间的变化,桑枝挥发物组分及总释放速率也随之发生改变。处理24 h后,桑枝释放出18种组分,比对照多11种组分,其总释放速率也明显提高,为对照的8.2倍;48 h后桑枝释放出22种组分,比对照多15种组分,其总释放速率进一步提高,为对照的44.6倍;72 h后桑枝释放出13种组分,比对照多6种组分,其总释放速率大幅降低,为对照的3.9倍,但与对照无显著差异。【结论】随着茉莉酸浓度的提高,桑枝对桑天牛卵啮小蜂的引诱活性逐渐增强。茉莉酸能诱导桑枝挥发物的大量释放及新组分的产生。     

桑天牛卵啮小蜂雌蜂对茉莉酸诱导的桑枝挥发物的触角电位和嗅觉反应

【目的】明确桑天牛卵啮小蜂Aprostocetus prolixus雌蜂对茉莉酸诱导的桑Morus alba枝挥发物的触角电位和嗅觉反应,有利于揭示茉莉酸诱导桑枝产生间接抗性的化学机制。【方法】采用动态顶空气体法收集茉莉酸处理后的桑枝挥发物,分别通过气相色谱-触角电位联用仪(GC-EAD)和气相色谱/质谱联用仪(GC/MS)筛选和鉴定对桑天牛卵啮小蜂雌蜂有EAD活性的化合物,并比较这些活性组分的释放速率在茉莉酸处理桑枝与蒸馏水处理的对照桑枝间的差异,最后利用Y-型嗅觉测定仪明确对该寄生蜂有引诱活性的组分。【结果】桑枝经茉莉酸处理后,其挥发物中的Z-3-己烯醇、γ-萜品烯、β-水芹烯、紫苏烯、水杨酸甲酯及3种未知化合物使桑天牛卵啮小蜂雌蜂产生明显的EAD反应,并且β-水芹烯、紫苏烯和水杨酸甲酯的释放量明显高于对照,其中β-水芹烯和紫苏烯仅存在于茉莉酸处理后桑枝的挥发物中,而Z-3-己烯醇的释放速率与对照无显著差异。0.1%β-水芹烯、0.1%紫苏烯以及0.01%和0.001%水杨酸甲酯对该蜂雌蜂具有显著的引诱作用。【结论】结果提示,茉莉酸促进桑枝大量释放β-水芹烯、紫苏烯和水杨酸甲酯,是茉莉酸诱导桑树对桑天牛产生间接抗性的重要机制。     

扶桑绵粉蚧取食为害对棉花萜类化合物释放的影响

在室内条件下采用机械损伤叶片(MW)、外源水杨酸诱导(Me SA)、扶桑绵粉蚧短期(S-MF)及长期为害(L-MF)4种方式处理棉花,对棉花植株释放的萜类化合物进行了定性与定量研究。结果表明,共有5种萜类化合物被定性检出,分别为α蒎烯、β蒎烯、长叶烯、A-柏木烯与雪松烯;扶桑绵粉蚧的取食为害显著提高了棉花α蒎烯、β蒎烯及A-柏木烯的释放量,并且新增加雪松烯与长叶烯的释放;而叶片机械损伤与外源水杨酸诱导处理在一定程度上也提高了α蒎烯、β蒎烯及A-柏木烯的释放量。本研究结果为合理利用虫害诱导植物挥发物进行扶桑绵粉蚧的生物防治提供科学依据。     

牧草盲蝽对七种寄主植物不同挥发物的EAG和行为反应

【目的】研究牧草盲蝽Lygus pmtensis对寄主植物挥发物的EAG及趋向行为反应,为研发牧草盲蝽引诱剂或趋避剂策略提供科学依据。【方法】利用固相微萃取方法收集7种寄主植物包括木地肤Kochia prostrata (L.) Schrad.、灰绿藜Chenopodium glaucum、花椰菜Brassica oleracea L.var.botrytis L.、小白菜Brassica campestris L.ssp.chinensis Makino、田旋花Convolvulus arvensis L.、小藜Chenopodium serotinum L.、番茄Lycopersicon esculentum Mill.的挥发物,通过室内气相-质谱联用系统(GC-MS)进行挥发物的定性及定量分析,最终测定了9种候选特征挥发物的触角电位(EAG)反应和嗅觉趋向行为反应。【结果】7种寄主植物共鉴定到的化合物有31种,且种类和含量有较大差异,差异显著。9种候选特征挥发物均能引起牧草盲蝽雌、雄成虫的EAG反应。其中牧草盲蝽雌、雄成虫对壬醛的EAG反应绝对值最大,雌、雄虫对不同植物挥发物质EAG反应相对值均有显著差异,且对同种化合物雌虫的反应相对值均大于雄虫的反应,乙酸顺式-3-己烯酯和壬醛引发的EAG反应值差异显著;趋向行为测定中,牧草盲蝽雌虫对壬醛、金合欢烯、α-蒎烯、1-石竹烯、乙酸顺式-3-己烯酯、2-甲基-1-醇的大部分浓度的行为反应差异显著,雄虫仅对α-蒎烯、壬醛的部分浓度的行为反应差异显著。【结论】7种寄主植物的挥发物对牧草盲蝽雌、雄成虫具有不同EAG和趋向行为反应影响,候选气味化合物可以作为设计牧草盲蝽引诱剂组分进行田间害虫防控实践。     

斜纹夜蛾取食对Bt玉米挥发物组成和含量的影响

采用顶空吸附法和气相色谱-质谱法研究了两个Bt玉米品种(5422Bt1, 5422CBCL)和一个同源常规玉米品种(5422)在健康和经斜纹夜蛾取食危害后两种状态下释放的挥发物组成和含量差异.结果表明：健康状态下,5422释放了(E)-β-罗勒烯、芳樟醇、（3E）-4,8-二甲基-1,3,7-壬三烯(DMNT)和(E)-β-法尼烯4种挥发物;5422Bt1释放了芳樟醇和DMNT 2种挥发物;而5422CBCL只释放芳樟醇1种挥发物.虫害后,在5422和5422Bt1的挥发物中鉴定出了萜类、醇类、 酯类和吲哚等12种化合物;在5422CBCL中鉴定出了10种,缺少(Z)-3-己烯-1-醇乙酸酯和橙花叔醇;3个品种释放的萜烯类化合物种类和含量均明显增加,其中,5422和5422Bt1增加了8种,5422CBCL增加了7种;5422Bt1和5422CBCL 的芳樟醇和DMNT释放量高于5422,其余化合物的释放量均低于常规品种,尤其是(E)-β-法尼烯显著低于5422.可见,经斜纹叶蛾取食诱导后,Bt玉米释放的挥发物种类和含量与常规玉米不同,且不同的Bt玉米品种（Bt11与MON810）之间也存在差异.     

田间条件下不同诱导棉花挥发性物质的鉴定

采用人工机械损伤(处理A)、棉铃虫为害(处理B)、棉铃虫为害+棉铃虫体(处理C)和水杨酸诱导(处理D)4种处理方式,对田间现蕾期棉花植株挥发性化合物进行了定性和定量研究.结果表明：有30多种棉株挥发性化合物被定性检出,对其中10种主要挥发性物质进行定量分析,田间棉株挥发的绿叶气味化合物有3-己酮、2-己酮和3-己醇等;单萜类化合物有α-蒎烯、β-蒎烯、β-月桂烯、3,7-二甲基,1,3,6-辛三烯等;脂肪族化合物有丙酸丁酯、乙酸戊酯、乙酸丁酯和3-甲基丁酸乙酯;芳香族化合物有苯乙酮、苯甲醛等.处理C和处理B的棉花挥发信息化合物种类和释放量均明显多于对照,这两个处理检测到3,7-二甲基,1,3,6-辛三烯;而处理A和处理D未检测到该化合物.与对照相比,处理A挥发物在种类和含量上差异不显著.在田间,处理B、处理C和处理D均能诱导促进棉株挥发物的释放.     

褐飞虱对水稻特异性挥发物的行为反应

【目的】本研究通过测试褐飞虱Nilaparvata lugens (St?l)对水稻特异性挥发物的行为反应,研究水稻特异性挥发物对褐飞虱选择行为的影响,寻找出对褐飞虱有驱避或引诱功效的水稻挥发物成分,为稻田褐飞虱综合治理提供理论基础。【方法】选择水稻十一烷、十六烷、十七烷、芳樟醇、植醇、2-乙基-1-葵醇、柠檬烯、月桂烯、壬醛、葵醛、2-十二酮、水杨酸甲酯12种挥发物,以正己烷作为溶剂分别配置1、10和100μL/mL 3种浓度处理,采用四臂嗅觉仪测试3种浓度的12种水稻挥发物对褐飞虱行为反应。【结果】发现6种水稻挥发物包括芳樟醇、水杨酸甲酯、植醇、壬醛、葵醛及2-十二酮显著驱避褐飞虱,仅发现月桂烯1种水稻挥发物成分可显著引诱褐飞虱。其中,芳樟醇和水杨酸甲酯在测试的3个浓度中均显著驱避褐飞虱,依照由低到高浓度,褐飞虱对化合物的选择率相较于对照分别下降92.3%、122.2%、242.9%（芳樟醇）,57.1%、70.6%、188.9%（水杨酸甲酯）,而其它4种驱避剂和1种引诱剂都在浓度达到100μL/mL时才显著影响褐飞虱行为反应。【结论】水稻中存在对褐飞虱具有较好驱避或引诱作用的特异性植物挥发物,可用于生产中开发有效植物源驱避剂或引诱剂用于水稻褐飞虱生态防控。     

水稻挥发物对稻虱缨小蜂的引诱效果研究

【目的】通过室内测定稻虱缨小蜂Anagrus nilaparvatae对水稻单一挥发物和混合挥发物的行为反应,研究水稻挥发物对稻虱缨小蜂的引诱效果,为进一步探索信息化合物在害虫防治中的应用提供理论依据。【方法】利用Y型嗅觉仪测定醇类、酮类、酚类、醛类、烯类和吲哚类等12种水稻单一挥发物对稻虱缨小蜂的引诱效果,利用引诱效果显著的单一化合物进行特定浓度的混配,进而测定稻虱缨小蜂对混合水稻挥发物的行为反应。【结果】单一挥发物中,香叶基丙酮(0.1 mg/L)、2-庚醇(1 mg/L)、正壬醇(10 mg/L)和β-石竹烯(0.01 mg/L)对稻虱缨小蜂有显著的引诱效果;对具有引诱效果的单一挥发物进行混配发现,No.1,No.3,No.4和No.10这4种组合的混合物对稻虱缨小蜂的行为有显著的影响。【结论】水稻挥发物能够影响稻虱缨小蜂的行为反应,但其引诱效果受挥发物种类、浓度和混配比例等多种因素的影响。     

红火蚁工蚁对棉蚜诱导的棉花挥发物的嗅觉和行为反应

【目的】红火蚁 Solenopsis invicta 与棉蚜 Aphis gossypii 存在兼性共生关系,红火蚁可能利用棉蚜危害诱导棉花释放的挥发物定位棉蚜。本研究将测试红火蚁工蚁对棉花挥发物的嗅觉和行为反应。【方法】使用Y型管实验测试红火蚁工蚁对棉花气味的行为反应;以红火蚁告警信息素2-乙基-3,5(6)-二甲基吡嗪为阳性对照,测试红火蚁工蚁对不同剂量(100, 10, 1 和0.1 μg)的9种棉花挥发物组分[α-蒎烯、β-蒎烯、β-石竹烯、( E, E )-4,8,12-三甲基-1,3,7,11-十三碳四烯(TMTT)、( E )-4,8-二甲基-1,3,7-壬三烯(DMNT)、辛醛、6-甲基-5-庚烯-2-酮、顺-3-己烯基乙酸酯和水杨酸甲酯]的触角电位反应;再利用Y型嗅觉仪测试这些挥发物对红火蚁工蚁的行为选择影响。【结果】结果表明,受棉蚜为害的棉花较健康棉花对红火蚁工蚁具有极显著的引诱效果。红火蚁对9种挥发物组分的EAG反应随着剂量升高而升高。各化合物在100 μg剂量时EAG反应值最大,其中,工蚁对水杨酸甲酯和6-甲基-5-庚烯-2-酮这两个化合物反应最强。在行为选择实验中,化合物水杨酸甲酯、6-甲基-5-庚烯-2-酮和DMNT对红火蚁工蚁均具有显著的引诱效果。【结论】棉蚜诱导的棉花挥发物中水杨酸甲酯和6-甲基-5-庚烯-2-酮对红火蚁有显著的引诱效果,这2种化合物可能在红火蚁定位棉蚜、建立共生关系中起着关键的作用。     

植物源挥发物对玉米田天敌昆虫的诱集效果比较

【目的】比较7种植物源挥发物反式-β-法尼烯、橙花叔醇、6-甲基-5-庚烯-2-酮、顺-3-己烯乙酸酯、丁香酚、芳樟醇、顺式茉莉酮在玉米田中对天敌昆虫的诱集效果,为利用植物源挥发物对玉米田害虫进行生物防治提供参考。【方法】将7种植物源挥发物制作挥发物引诱球,利用水盆诱捕器、粘虫板和五点取样法调查百株虫量,比较7种植物源挥发物对捕食性和寄生性天敌昆虫的诱集效果。【结果】在7种植物源挥发物的筛选中,橙花叔醇对黄缘蜾蠃Anterhynchium flavomarginatum较其它6种化合物和对照的诱集效果有明显差异,顺式茉莉酮对黑带食蚜蝇Episyrphus balteatus较其它6种化合物和对照的诱集效果有明显差异,反式-β-法尼烯和顺式茉莉酮对龟纹瓢虫Propylaea japonica较其它5种化合物和对照的诱集效果有明显差异;在橙花叔醇和顺式茉莉酮的小区试验中,2种挥发物对龟纹瓢虫和异色瓢虫Harmonia axyridis的诱集效果明显优于对照,橙花叔醇对黑带食蚜蝇和虎斑食虫虻Astochia virgatipes的诱集效果明显优于对照。【结论】在7种植物源挥发物中,对玉米田天敌昆虫的诱集效果,橙花叔醇较好,顺式茉莉酮和反式-β-法尼烯次之。     

假眼小绿叶蝉对茶梢挥发物的行为反应

【目的】研究假眼小绿叶蝉Empoasca vitis G?the对健康茶梢和蝉害茶梢挥发物的行为反应,筛选出可引诱假眼小绿叶蝉的茶梢挥发物。【方法】以动态吸附法收集健康茶梢和蝉害茶梢挥发物,用气相色谱–质谱联用仪(GC-MS)进行定性定量分析,借助于Y形嗅觉仪检测多种挥发物引诱假眼小绿叶蝉成虫的活性。【结果】从健康茶梢和蝉害茶梢中共鉴定出30种挥发物组分,其中烯烃类含量较大。健康茶梢和蝉害茶梢挥发物中共有组分有13种,蝉害之后其含量皆上升,其中Z-b-罗勒烯和乙酸叶醇酯的含量分别是健康茶梢中的142.27倍、12.90倍。蝉害茶梢中新出现的组分有12种,其中紫苏烯含量较高。在10-2、10~(-4)、10-6 g/mL浓度下,乙酸叶醇酯表现出极显著的引诱水平(P<0.01);紫苏烯在10~(-2)和10~(-4) g/mL浓度下表现出极显著引诱水平(P<0.01);10~(-4) g/mL浓度下,Z-b-罗勒烯和D-柠檬烯极显著引诱假眼小绿叶蝉(P<0.01);10~(-4) g/mL芳樟醇、10~(-6) g/mL乙酸正丁酯和10~(-6) g/mL D-柠檬烯呈现出显著引诱水平(P<0.05);混合物组分Blend1和Blend2分别表现出极显著和显著引诱水平;而10~(-6) g/mLa-法尼烯显著排斥假眼小绿叶蝉(P<0.05)。【结论】假眼小绿叶蝉成虫对健康茶梢和蝉害茶梢挥发物多种组分具有不同的行为反应,引诱效果较强的单组分或混合组分的选定可为田间引诱效果试验提供参考。     

Manipulation of VOC emissions with methyl jasmonate and carrageenan in the evergreen conifer Pinus sylvestris and evergreen broadleaf Quercus ilex

Plant defence can be induced by exposing plants to the plant hormone jasmonic acid (JA) or its volatile ester, methyl jasmonate (MeJA). Carrageenans (Carr) - sulphated D-galactans extracted from red algae - can also induce plant defences. In this study, the effects of exogenous MeJA and Carr application (concentration 300 and 12.7 μmol, respectively) on volatile emissions from two widespread evergreen woody species, Pinus sylvestris (nine Turkish and one Finnish provenance) and Quercus ilex (Italian provenance) were investigated. We collected headspace samples from seedlings and analysed the quality and quantity of volatile compounds emitted by treated and control plants. In total, 19 monoterpenes, 10 sesquiterpenes, 10 green leaf volatiles (GLVs) and two aromatic compounds were emitted by P. sylvestris from all the provenances studied. Foliar MeJA application clearly affected the volatile profiles of trees from all the provenances. Effects of Carr were genotype specific. In Q. ilex, emissions of sesquiterpenes, GLVs and the homoterpene (E)-DMNT were all induced by MeJA application. However, emissions of most constitutively emitted monoterpenes were significantly reduced. Carr application also led to a significant reduction in monoterpene emissions, but without corresponding increases in other emissions. Our results indicate that exogenously applied MeJA and Carr can both significantly modify the volatile profiles of P. sylvestris and Q. ilex, but also that there are important provenance- and species-specific differences in the overall degree of elicitation and compositions of elicited compounds.     

Induction of priming by cold stress via inducible volatile cues in neighboring tea plants

Plants have evolved sophisticated defense mechanisms to overcome their sessile nature. However, if and how volatiles from cold‐stressed plants can trigger interplant communication is still unknown. Here, we provide the first evidence for interplant communication via inducible volatiles in cold stress. The volatiles, including nerolidol, geraniol, linalool, and methyl salicylate, emitted from cold‐stressed tea plants play key role(s) in priming cold tolerance of their neighbors via a C‐repeat‐binding factors‐dependent pathway. The knowledge will help us to understand how plants respond to volatile cues in cold stress and agricultural ecosystems.     

茉莉酸在植物诱导防御中的作用

茉莉酸(JA)和茉莉酸甲酯(MeJA)作为与损伤相关的植物激素和信号分子,广泛地存在于植物体中,外源应用能够激发防御植物基因的表达,诱导植物的化学防御,产生与机械损伤和昆虫取食相似的效果。大量研究表明,用茉莉酸类化合物处理植物可系统诱导蛋白酶抑制剂(PI)和多酚氧化酶(PPO),从而影响植食动物对营养物质的吸收,还能增加过氧化物酶、壳聚糖酶和脂氧合酶等防御蛋白的活性水平,导致生物碱和酚酸类次生物质的积累,增加并改变挥发性信号化合物的释放,甚至形成防御结构,如毛状体和树脂导管。经茉莉酸处理的植物提高了植食动物的死亡率,变得更加吸引捕食性和寄生性天敌。挥发性化合物——茉莉酸甲酯可以从植物的气孔进入植物体内,在细胞质中被酯酶水解为茉莉酸,实现长距离的信号传导和植物间的交流,诱导邻近植物产生诱导防御反应。茉莉酸和茉莉酸甲酯分别具有4种立体异构,其中具有活性的是顺式结构,但顺式结构不稳定,会差向异构化为反式结构。茉莉酸的代谢物(Z)-茉莉酮(cis-Jasmone)具电生理活性,在植物诱导防御中起作用,并且在防御信号的作用上不同于茉莉酸和茉莉酸甲酯。     

Aphid Acceptance of Barley Exposed to Volatile Phytochemicals Differs Between Plants Exposed in Daylight and Darkness

It is well known that volatile cues from damaged plants may induce resistance in neighboring plants. Much less is known about the effects of volatile interaction between undamaged plants. In this study, barley plants, Hordeum vulgare cv. Kara, were exposed to volatiles from undamaged plants of barley cv. Alva or thistle Cirsium vulgare, and to the volatile phytochemicals, methyl salicylate or methyl jasmonate. Exposures were made either during natural daylight or darkness. Acceptance of exposed plants by the aphid Rhopalosiphum padi was assessed, as well as the expression of putative marker genes for the different treatments. Aphid acceptance of plants exposed to either barley or C. vulgare was significantly reduced, and an effect of the volatiles from undamaged plants was confirmed by the induction of pathogenesis-related protein, PR1a in exposed plants. However the effect on aphid acceptance was seen only when plants were exposed during darkness, whereas PR1a was induced only after treatment during daylight. Aphid acceptance of plants exposed to either methyl salicylate or methyl jasmonate was significantly reduced, but only when plants were exposed to the chemicals during daylight. AOS2 (allene oxide synthase) was induced by methyl jasmonate and BCI-4 (barley chemical inducible gene-4) by methyl salicylate in both daylight and darkness. It is concluded that (a) the effects on aphids of exposing barley to volatile phytochemicals was influenced by the presence or absence of light and (b) the response of barley to methyl salicylate/methyl jasmonate and to volatiles from undamaged plants differed at the gene and herbivore level.Key Words: methyl jasmonate, methyl salicylate, allelobiosis, barley, PR1, allene oxide synthase, Rhopalosiphum padi, light     

诱茶尺蠖天敌寄生蜂的茶树挥发物的分离与鉴定

采用Tenax GC动态吸附法对茶树-茶尺蠖Ectropis obliqua (Prout)-单白绵绒茧蜂Apanteles sp.三重营养关系中茶树的新梢挥发性化合物进行了捕集,经GC、GC-MS鉴定结果表明,不同来源的挥发物的组成和数量是不同的,完整茶树新梢(IS)的挥发物有11种组份;机械损伤新梢(MDS)的挥发物有13种组份;茶树-茶尺蠖取食复合体(PHC)的挥发物有15种组份,而用经典的SDE法获得的新梢精油有13种组份,4种挥发物数量的大小顺序为SDE>MDS>PHC>IS。生物测定结果表明,无气味经历的雌单白绵绒茧蜂对IS和MDS的气味的选择作用无统计上的显著性,对机械损伤新梢+幼虫口腔分泌物(MDS+Reg), 幼虫取食损伤(LDS)和PHC的气味有较强的偏好选择性。     

Herbivore-induced Blueberry Volatiles and Intra-plant Signaling

Herbivore-induced plant volatiles (HIPVs) are commonly emitted from plants after herbivore attack^1,2. These HIPVs are mainly regulated by the defensive plant hormone jasmonic acid (JA) and its volatile derivative methyl jasmonate (MeJA)^3,4,5. Over the past 3 decades researchers have documented that HIPVs can repel or attract herbivores, attract the natural enemies of herbivores, and in some cases they can induce or prime plant defenses prior to herbivore attack. In a recent paper⁶, I reported that feeding by gypsy moth caterpillars, exogenous MeJA application, and mechanical damage induce the emissions of volatiles from blueberry plants, albeit differently. In addition, blueberry branches respond to HIPVs emitted from neighboring branches of the same plant by increasing the levels of JA and resistance to herbivores (i.e., direct plant defenses), and by priming volatile emissions (i.e., indirect plant defenses). Similar findings have been reported recently for sagebrush⁷, poplar⁸, and lima beans⁹..Here, I describe a push-pull method for collecting blueberry volatiles induced by herbivore (gypsy moth) feeding, exogenous MeJA application, and mechanical damage. The volatile collection unit consists of a 4 L volatile collection chamber, a 2-piece guillotine, an air delivery system that purifies incoming air, and a vacuum system connected to a trap filled with Super-Q adsorbent to collect volatiles^5,6,10. Volatiles collected in Super-Q traps are eluted with dichloromethane and then separated and quantified using Gas Chromatography (GC). This volatile collection method was used n my study⁶ to investigate the volatile response of undamaged branches to exposure to volatiles from herbivore-damaged branches within blueberry plants. These methods are described here. Briefly, undamaged blueberry branches are exposed to HIPVs from neighboring branches within the same plant. Using the same techniques described above, volatiles emitted from branches after exposure to HIPVs are collected and analyzed.     

外源化合物诱导后小麦对麦长管蚜和粘虫的抗虫性研究

喷施外源化合物和昆虫取食均可诱导小麦的防御反应,如挥发物组成发生改变、某些次生物质含量增加或减少,进而影响昆虫和天敌的行为反应。本实验中小麦苗经茉莉酸或几丁质喷施诱导,可显著提高小麦中丁布的含量,但茉莉酸甲酯的诱导作用不明显。喷施茉莉酸及麦长管蚜或粘虫取食诱导小麦,会导致小麦挥发物的种类及含量与对照相比有显著不同,3种处理间小麦的挥发物也存在显著差异。用经茉莉酸处理的麦苗饲养麦长管蚜和粘虫,可显著抑制二者的生长发育速度,使体重减轻,并导致麦长管蚜繁殖力下降。经茉莉酸处理的麦苗的挥发物对粘虫寄生蜂有吸引作用,表明茉莉酸在诱导小麦产生直接抗虫性的同时,还能诱导其释放吸引天敌的挥发性化合物从而产生间接抗性。     

二化螟与稻纵卷叶螟幼虫取食诱导的水稻挥发物比较

前期研究结果表明,二化螟和稻纵卷叶螟幼虫为害所诱导的水稻挥发物能对二化螟绒茧蜂Apanteles chilonis Munakata、二化螟Chilo suppressalis(Walker)和稻纵卷叶螟Cnaphalocrocis medinalis(Guene)雌成虫的行为产生影响,并且两者的影响效应存在明显差异,但至今仍不清楚2种害虫危害后水稻挥发物的变化情况。利用动态吸附法对健康水稻苗、二化螟或稻纵卷叶螟幼虫为害苗的挥发物进行捕集与鉴定。在3种处理水稻苗中,共捕集到28种挥发物组分,包括萜类化合物、烷烃类化合物、酮类、醇类、水杨酸甲酯和一些未知化合物。二化螟和稻纵卷叶螟为害均能导致水稻挥发物总量和大多挥发物组分释放量的上升;同时,二化螟幼虫危害能诱导水稻新释放2-heptanonol,(E)-linalooloxide和2种未知挥发物组分,稻纵卷叶螟为害则可诱导水稻产生2-heptanonol,(E)-linalooloxide,MeSA和β-caryophyllene4种新化合物。2种虫害稻株间的比较表明,β-caryophyllene和MeSA是稻纵卷叶螟危害水稻后诱导产生的特有挥发物组分,并且linalool,α-copaene,(+)-cedrol,n-heptadecane和n-nonadecane在二化螟为害苗与稻纵卷叶螟为害苗之间差异显著。这一结果也许可以解释2种害虫诱导水稻挥发物对天敌和害虫行为影响不同的原因。     

Variability and stability of tea weevil‐induced volatile emissions from tea plants with different weevil densities,photoperiod and infestation duration

Abstract After herbivore attack, many plants emit herbivore‐induced plant volatiles (HIPVs). HIPVs can attract carnivores and/or repel herbivores, thereby mediating tritrophic plant–herbivore–carnivore interactions. HIPVs act as chemical information between organisms; hence, their variability and stability are vital. In the present study, variations in the volatile emissions, from the tea plant Camellia sinensis (O. Ktze) damaged by the tea weevil Myllocerinus aurolineatus (Voss) (Coleoptera: Curculionidae), with weevil densities, photoperiod and infestation duration, were investigated. The volatiles induced by high‐density weevils were more abundant in composition and amount than those induced by low‐density weevils, whether at noon, night or after weevil removal. The induced volatile emissions were similar on the second and third day after infestation, and the emissions of the major induced compounds displayed diurnal cycles. Linalool, (E,E)‐α‐farnesene, and benzyl nitrile were emitted mainly at noon, whereas 1,3,8‐p‐menthatriene and (E)‐β‐ocimene were maximally emitted at night. Given the different emission dynamics, significant differences were found between noon‐ and night‐induced volatiles. In summary, tea plants damaged by different weevil densities emitted a relatively stable signal at a particular time. This stability could be attributed to the similarities under the two densities of the main induced volatile compounds, their relative ratios and the emission dynamics of the induced volatiles.