Nocturnal herbivore-induced plant volatiles attract the generalist predatory earwig <Emphasis Type="Italic">Doru luteipes</Emphasis> Scudder

Numerous studies have demonstrated that entomophagous arthropods use herbivore-induced plant volatile (HIPV) blends to search for their prey or host. However, no study has yet focused on the response of nocturnal predators to volatile blends emitted by prey damaged plants. We investigated the olfactory behavioral responses of the night-active generalist predatory earwig Doru luteipes Scudder (Dermaptera: Forficulidae) to diurnal and nocturnal volatile blends emitted by maize plants (Zea mays) attacked by either a stem borer (Diatraea saccharalis) or a leaf-chewing caterpillar (Spodoptera frugiperda), both suitable lepidopteran prey. Additionally, we examined whether the earwig preferred odors emitted from short- or long-term damaged maize. We first determined the earwig diel foraging rhythm and confirmed that D. luteipes is a nocturnal predator. Olfactometer assays showed that during the day, although the earwigs were walking actively, they did not discriminate the volatiles of undamaged maize plants from those of herbivore damaged maize plants. In contrast, at night, earwigs preferred volatiles emitted by maize plants attacked by D. saccharalis or S. frugiperda over undamaged plants and short- over long-term damaged maize. Our GC-MS analysis revealed that short-term damaged nocturnal plant volatile blends were comprised mainly of fatty acid derivatives (i.e., green leaf volatiles), while the long-term damaged plant volatile blend contained mostly terpenoids. We also observed distinct volatile blend composition emitted by maize damaged by the different caterpillars. Our results showed that D. luteipes innately uses nocturnal herbivore-induced plant volatiles to search for prey. Moreover, the attraction of the earwig to short-term damaged plants is likely mediated by fatty acid derivatives.     

Extraction and quantification of "condensed tannins" as a measure of plant anti-herbivore defence? Revisiting an old problem

Contents of phenolic compounds in leaf extracts often serve as a measure of plant anti-herbivore defence. This method suffers from the multifunctionality of phenolics and from problems with their colorimetric quantification. Here we present further evidence for the pertinence of these problems. Contents of condensed tannins (CCT) were spectrophotometrically quantified in leaf extracts of 11 closely related mimosoid species, and Spodoptera littoralis caterpillars were reared on artificial diet containing these extracts. The relationship of CCT with caterpillar growth differed considerably among plant species, since both positive and negative correlations were detected. There was, however, a negative correlation of CCT with fungal spore germination, indicating a role of these compounds in resistance to fungi. Detailed knowledge on the structure and biological function of defensive compounds and on the overall composition of leaves is required to estimate a plant's defensive efficacy against a particular group of enemies.     

苗期玉米、大豆在土壤-植物系统N2O排放中的贡献

为区分植物在土壤-植物系统N₂O排放中的贡献,用封闭式箱法对在温室内砂培和土培的玉米、大豆幼苗及砂、土、砂-植物系统、土壤-植物系统的N2O排放进行了测定,同时对植物N₂O排放与植物叶片中的硝酸还原酶(NR)活性及NO₃^--N、NO₂^--N含量的关系进行了分析.结果表明:在53d的观测期内,玉米、大豆幼苗本身均可排放N₂O,且在土壤(砂)-植物系统的N₂O排放中占有很大份额(79.18%～100%);植物N₂O的排放与植物叶片的硝酸还原酶活性和NO₃^--N、NO₂^--N的含量显著正相关(R²≥0.97,n=6).     

冬季绿肥对黄土高原旱作春玉米农田土壤温室气体排放的影响

利用田间试验研究了冬季绿肥对旱作春玉米农田土壤温室气体排放的影响.试验设燕麦、小扁豆、燕麦与小扁豆混播和裸地休闲共4个处理,采用静态箱-气相色谱法对冬闲期和春玉米生长期间土壤温室气体（CO₂、N₂ O和CH₄）排放通量进行观测.结果表明,旱作春玉米-冬季绿肥种植系统土壤是CO₂、N₂ O的排放源和CH₄的吸收汇.与裸地休闲相比,燕麦和小扁豆在冬闲期对土壤CO₂累积排放量没有影响,但在春玉米生长期间导致土壤CO₂累积排放量分别增加了7.77%和25.7%（P<0.05）,混播导致冬闲期和春玉米生长期间土壤CO₂累积排放量分别增加了19.1%和14.5%（P<0.05）.种植燕麦后冬闲期和春玉米生长期间土壤N₂ O累积排放量较裸地休闲分别降低了11.6%和14.7%（P<0.05）,而小扁豆分别增加了31.9%和14.9%（P<0.05）;混播导致冬闲期土壤N₂ O累积排放量降低了19.2%（P<0.05）,但在春玉米生长期间差异不显著.与裸地休闲相比,燕麦、小扁豆和混播冬闲期土壤CH₄累积吸收量分别降低了37.9%、23.6%和29.6%（P<0.05）,春玉米生长期间分别降低了19.4%、33.5%和31.5%（P<0.05）,其中小扁豆和混播在冬闲期和春玉米生长期间差异均不显著.燕麦较裸地休闲在农田综合增温潜势（GWP）、春玉米产量和温室气体排放强度（GHGI）差异均不显著.小扁豆和混播显著提高了GWP,其中小扁豆显著高于混播.而与裸地休闲相比,小扁豆和混播分别提高了春玉米产量的20.3%和15.4%（P<0.05）,但对GHGI没有显著影响.综合考虑GWP、春玉米产量和GHGI,本地区冬闲期间将小扁豆和燕麦二者混播能增加春玉米产量的同时有效降低土壤温室气体排放强度.     

水热法制备玉米叶基生物炭对亚甲基蓝的吸附性能研究

以农业废弃物玉米叶和玉米秆为原材料,采用水热法制备生物炭,通过批试验方法考察了接触时间、污染物初始浓度、生物炭投加量、反应体系温度及溶液p H值等因素对2种生物炭吸附亚甲基蓝的影响,并对吸附规律进行了探讨.吸附动力学拟合结果发现,准二级动力学能更好地拟合吸附过程(R~2=0.9986~0.9999);颗粒内扩散方程拟合结果表明,2种生物炭对亚甲基蓝的吸附由液膜扩散和颗粒内扩散2个过程控制.玉米叶基生物炭对亚甲基蓝的吸附可以通过Freundlich方程来进行拟合(R~2=0.9898),说明吸附在生物炭表面是多分子层吸附过程;而玉米杆基生物炭对亚甲基蓝的吸附更符合Langmuir方程(R~2=0.9825),说明吸附在生物炭表面是单分子层吸附过程.与玉米杆基生物炭相比,玉米叶基生物炭具有更好的吸附性能,拟合理论最大吸附量为玉米杆基生物炭的1.25倍.     

接种AM真菌对玉米生长的影响及叶片全氮含量的高光谱估测

为了快速、准确测定玉米叶片中的全氮含量,实现利用高光谱遥感技术对微生物修复作用下氮元素的监测,现设接种丛枝菌根(M)和不接种菌根的对照组(CK),分别测定2个处理下叶片理化参数和光谱反射率数据,研究接种AM真菌对玉米生长的影响并采用逐步回归分析法建模反演叶片全氮含量。结果表明:接种AM真菌可提高不同叶位的叶片全氮、全磷、全钾及叶绿素含量,同时显著提高玉米的生物量和叶片含水率;不同的处理组中全氮含量对不同特征参数的相关性显著情况相同,但相关系数有所差异;2个处理均使用逐步线性回归法,以筛选出的9个极显著相关的光谱特征参数为自变量,对玉米叶片氮含量建模。其中,CK中模型决定系数R2最高可达0.8361,M组中模型的决定系数最高可达0.893,可以较好地估测玉米叶片全氮含量。     

Different uses of plant semiochemicals in host location strategies of the two tachinid parasitoids

Some members of the family Tachinidae (Insecta: Diptera) deposit numerous very small eggs, termed “microtype” eggs, on the food plants of their caterpillar hosts. Parasitization is successful only when the hosts ingest these eggs. To increase the chance of hosts encountering the eggs, microtype tachinid parasitoids have to choose a suitable plant that harbors hosts and lay their eggs near the hosts. In their host location process, semiochemicals emitted by host-infested plants offer the tachinids a reliable cue. We investigated the behavioral responses of two microtype tachinid parasitoids, Pales pavida and Zenillia dolosa, to maize plants infested with their caterpillar host, Mythimna separata, in a wind tunnel. P. pavida females showed a significantly higher rate of landing on caterpillar-infested plants than on mechanically wounded or intact plants, whereas Z. dolosa landed on both the caterpillar-infested and mechanically wounded plants at significantly higher rates than on intact plants. We also examined which part of a caterpillar-infested maize leaf induces oviposition. P. pavida deposited eggs on the margin of the leaf, whereas Z. dolosa preferentially laid eggs around a caterpillar-infested area or a mechanically wounded spot. P. pavida eggs retained their parasitization ability for more than 15?days after they were deposited, whereas the eggs of Z. dolosa could not survive more than 5?days after oviposition. Our results suggest that each tachinid parasitoid employs a different host location strategy to exploit semiochemicals coming from plant–herbivore interaction as cues in order to increase their parasitization success.     

秸秆还田配施生物炭对关中平原夏玉米产量和土壤N2O排放的影响

为探明秸秆还田配施生物炭对夏玉米产量和土壤氧化亚氮（N₂O）排放的影响,基于2019~2020年关中平原田间定位试验,利用静态暗箱-气相色谱法监测了土壤N₂O排放通量,综合分析夏玉米产量、土壤N₂O排放和土壤活性氮组分,明确了秸秆还田配施生物炭在培肥土壤、增产减排方面的效应.以秸秆不还田（S₀）为对照,设置秸秆还田（S）和秸秆还田配施生物炭（SB）共3个处理.结果表明,各处理N₂O排放峰值出现在秸秆还田后10 d,秸秆还田30 d后土壤N₂O排放通量处于较低水平,土壤N₂O排放通量与铵态氮（NH₄⁺-N）、无机氮、微生物量氮（MBN）和可溶性有机氮（DON）含量呈显著的正相关关系（P<0.05）.S较S₀显著增加夏玉米产量、N₂O累积排放量、单位产量N₂O累积排放量和土壤总氮（TN）含量,分别为7.4%~13%、65.8%~132.2%、54.6%~103%和27.8%~33%.虽然SB较S提高夏玉米产量（2.5%~3.3%）的趋势不显著（P>0.05）,但是SB较S显著降低N₂O累积排放量和单位产量N₂O累积排放量,分别为24.0%~27.3%和26.4%~29.2%.在土壤N₂O排放通量达到峰值时,SB较S显著降低土壤N₂O排放通量45.1%~69.6%,生物炭能够缓解秸秆还田所诱发的土壤N₂O排放,具有削峰的作用.SB较S显著增加土壤总氮9.1%~12.2%.综合作物产量、N₂O排放和土壤总氮,对夏玉米生产而言,秸秆还田配施生物炭不仅培肥地力,提高夏玉米产量,而且减少单位产量N₂O累积排放量,是可供推广的兼顾作物产量和环境友好的适宜管理措施.     

模拟酸雨对菜豆叶片的伤害和Mefluidide保护效应的研究

酸雨的污染和危害已成为一个世界性的问题,我国的酸雨危害也日渐引起关注.由于酸雨所涉及到的地区不少是农作区,必然会危及农作物的产量.近年来对酸雨危害作物的机理已有报道,但关于寻求保护作物免于酸雨危害的研究则不多见.已有报道,Mefluidide(N-[2,4-dimethyl-5-[(trifluoromethyl)sulfonyl]amino]phenylacetamide)(N-[2,4-二甲基-5-[(三氟甲基)磺酰]氨基]苯乙酰胺),一种合成的植物生长调节物质,对植物生长和发育以及物质代谢都有影响,尤其是能有效地保护低温敏感作物免于冷害,而且发现Mefluidide处理的植物,在冷害期间不表现细胞膜透性的增加.另外,有人发现pH2.0—4.0的模拟酸雨喷洒植株(青菜、菠菜和萝卜等)也会导致膜透性增加.我们以模拟酸雨引起菜豆叶片的伤害症状和一些生理指标为依据,     

生物可降解地膜覆盖对关中地区小麦-玉米农田温室气体排放的影响

为探究生物可降解地膜覆盖对冬小麦-夏玉米轮作农田生态系统温室气体排放的影响,布设了普通地膜覆盖（PM）、生物可降解地膜覆盖（BPM）和无覆盖（CK）这3个处理,采用静态暗箱-气相色谱仪法监测了2018～2019年土壤CO₂、 CH₄和N₂O的排放通量,并用水分利用效率（WUE）、温室气体排放强度（GHGI）和净生态系统经济预算（NEEB）指标评估覆膜对作物产量、农田环境和经济效益的影响.结果表明,与CK相比,PM和BPM增加了玉米季土壤CO₂的排放,PM处理下CO₂排放总量高于BPM处理（P>0.05）.PM和BPM处理均能够显著减少土壤对CH₄的吸收,CH₄的年吸收量较CK处理分别减少了42.0%和24.2%（P<0.05）.与CK相比,PM和BPM增加了小麦季N₂O排放总量（P>0.05）,而显著降低了夏玉米季N₂O排放（P<0.05）.覆膜能够提高作物产量和水分...     

长期定位有机物料还田对关中平原夏玉米-冬小麦轮作土壤NO排放的影响

农田土壤是大气光化学活性气体一氧化氮(NO)的主要人为源之一.为定量研究有机物料还田对NO排放的影响,利用静态暗箱法对关中平原26 a长期定位施肥夏玉米-冬小麦轮作农田NO排放通量进行周年(2016年6月至2017年6月)观测.除对照(CK)处理全年不施肥外,田间设3个施肥处理,冬小麦季分别为全化肥(NPK,165 kg·hm~(-2))、化肥加秸秆[NPKS,(165+40)kg·hm~(-2)]和化肥加牛粪[NPKM,(50+115)kg·hm~(-2)];夏玉米季均施等量化肥(188 kg·hm~(-2)).观测期内,CK处理NO排放通量较小[12.2 g·(hm~2·d)~(-1)];各施肥处理均在夏玉米播种、施肥和冬小麦施肥后出现排放峰,其中NPK处理峰值最高[112.0 g·(hm~2·d)~(-1)].各处理NO年排放总量和排放系数分别为0.13~0.57 kg·hm~(-2)和0.04%~0.12%.NPKS和NPKM处理年排放总量较NPK分别减少17.6%和增加68.0%(P0.05).与NPK处理相比,NPKS和NPKM冬小麦季排放总量降低41.1%~60.0%(P0.05);但夏玉米季增加25.2%~292.1%(P0.05).冬小麦季添加有机物料有效降低NO排放,而夏玉米季NO排放增加则与土壤有机质含量有关.     

Host manipulation by the orange leafhopper Cicadulina bipunctata: gall induction on distant leaves by dose-dependent stimulation

The evolution of the gall-inducing ability in insects and the adaptive significance of the galling habit have been addressed by many studies. Cicadulina bipunctata, the maize orange leafhopper, is an ideal study organism for evaluating these topics because it can be mass-reared and it feeds on model plants such as rice (Oryza sativa) and maize (Zea mays). To reveal differences between gall inductions by C. bipunctata and other gall inducers, we conducted four experiments concerning (a) the relationship between the feeding site and gall-induction sites of C. bipunctata on maize, (b) the effects of leafhopper sex and density, (c) the effects of length of infestation on gall induction, and (d) the effects of continuous infestation. C. bipunctata did not induce galls on the leaves where it fed but induced galls on other leaves situated at more distal positions. The degree of gall induction was significantly correlated with infestation density and length. These results indicate that C. bipunctata induces galls in a dose-dependent manner on leaves distant from feeding sites, probably by injecting chemical(s) to the plant during feeding. We suggest that insect galls are induced by a chemical stimulus injected by gall inducers during feeding into the hosts.     

Alcoholism in cockchafers: orientation of male Melolontha melolontha towards green leaf alcohols

Chemical orientation of the European cockchafer, Melolontha melolontha L., a serious pest in agriculture and horticulture, was investigated by field tests and electrophysiological experiments using plant volatiles. In total, 16 typical plant volatiles were shown to elicit electrophysiological responses in male cockchafers. Funnel trap field bioassays revealed that green leaf alcohols (i.e. (Z)-3-hexen-1-ol, (E)-2-hexen-1-ol and 1-hexanol) attracted males, whereas the corresponding aldehydes and acetates were behaviourally inactive. Furthermore, male cockchafers were attracted by volatiles from mechanically damaged leaves of Fagus sylvatica L., Quercus robur L. and Carpinus betulus L. However, volatiles emitted by damaged leaves of F. sylvatica attracted significantly more males than those from the other host plants. Odour from intact F. sylvatica leaves was not attractive to M. melolontha males. Females were not attracted by any of the tested volatile sources. The results suggest that plant volatiles play a similar role as a sexual kairomone in mate finding of M. melolontha, as has been shown for the forest cockchafer, Melolontha hippocastani F. Nevertheless, both species show remarkable differences in their reaction to green leaf alcohols.     

秸秆还田对冬小麦-夏玉米农田土壤固碳、氧化亚氮排放和全球增温潜势的影响

旱地农田温室气体净排放(以全球增温潜势表示)主要取决于土壤固碳速率和氧化亚氮(N2O)排放量.基于长期定位施肥试验,综合分析2010～2017年表层(0～20 cm)土壤有机碳含量和2014～2017年N2O排放通量的观测结果,定量评价秸秆还田对关中平原冬小麦-夏玉米农田土壤固碳速率、N2O年排放量和全球增温潜势的影响...     

广西百色植烟区土壤及烟株硼含量特征研究

为了科学补充烟田土壤硼元素,平衡土壤与烟株之间的硼营养,并最终改善烟叶品质,本研究选择广西百色靖西市壬庄乡史典村、化峒镇三友村及德保县燕峒乡那布村植烟区为研究对象,分析了烟株及其根系土壤的硼素含量特征。结果表明:(1)史典村土壤全量硼变化范围为35.23～90.47mg/kg,平均值为52.44±14.5mg/kg,处于中等水平;三友村变化范围为19.27～42.01mg/kg,平均值为28.26±6.72mg/kg,处于缺乏水平;那布村变化范围为84.28～130.71mg/kg,平均值为110.76±13.7mg/kg,处于丰富水平;(2)三块烟田上部烟叶硼含量处于适宜水平的占4.17%,其余均处于高含量水平;中部烟叶硼含量处于适宜水平的占20%,其余均处于高含量水平;三友村下部烟叶硼含量处于适宜水平的占60%,处于低水平及欠缺水平的占40%。三块烟田烟株的烟茎、上部及中部烟叶的钙硼比均低于1340,处于不缺硼状态;三友村下部烟叶钙硼比略高于1500,处于缺硼状态;(3)三块烟田烟株硼含量均为上部烟叶>中部烟叶>烟茎,两两之间具有显著性差异(P＜0.05),即硼在新生组织中含量较成熟组织高;(4)土壤pH与土壤硼含量及上部烟叶硼含量呈极显著负相关,与烟茎硼及中部烟叶硼含量呈显著负相关;上部烟叶硼含量与土壤硼含量呈极显著正相关,中部烟叶硼含量与土壤硼含量呈显著正相关,说明可在一定范围内改良土壤pH及调节土壤硼含量,以提升烤烟品质。     

能源植物修复土壤镉污染过程中细菌群落分析

选取油脂类能源植物大豆和碳水化合物类能源植物玉米,采用高通量测序方法研究大豆、玉米修复Cd污染土壤过程中根际土壤细菌群落组成.结果表明,100 mg·kg-1Cd的添加会抑制玉米、大豆生长,其中,大豆生物量降低比玉米高.不同组织中根部Cd积累量最高,转移系数TF分别为0.56(玉米)和0.14(大豆).基于Mi Seq的群落分析表明,大豆、玉米根际土壤细菌主要包括Proteobacteria(变形菌门)、Acidobacteria(酸杆菌门)、Gemmatimonadetes(芽单胞菌门)、Actinobacteria(放线菌门)、Bacteroidetes(拟杆菌门)等33个门.细菌群落的PCo A和UPGMA分析表明,Cd的添加和能源植物种植均能对细菌群落结构产生影响,其中,Cd的添加影响最大.Gemmatimonas、Flavisolibacter、Flexibacter、Ramlibacter、Ohtaekwangia、Flavitalea等细菌在Cd胁迫条件或大豆、玉米种植条件下相对丰度有所变化,分析其可能在大豆、玉米耐受Cd污染中起作用.     

镉在3种乔木中的积累及其亚细胞分布和化学形态研究

研究不同镉（Cd）浓度（0、25、50、100、200 mg·kg^-1）处理下,栾树（Koelreuteria paniculata）、臭椿（Ailanthus altissima）、银杏（Ginkgo biloba）3种乔木叶、枝、根中Cd的含量与积累特征,并分析Cd对其叶片超微结构的影响,探讨Cd在3种乔木叶片与根系中的亚细胞分布和化学形态特征.结果表明,3种乔木体内的Cd含量随着土壤Cd处理浓度的增加而增加,且主要积累在根部.栾树和臭椿各器官中的Cd含量显著高于银杏,表明栾树和臭椿对Cd的积累能力强于银杏.高浓度Cd处理下,栾树和臭椿叶片细胞结构损伤明显,细胞内出现大量黑色絮状物,且附着在细胞壁及细胞器的表面.而银杏叶片细胞无明显损伤特征,说明银杏对Cd的耐受性强于栾树和臭椿.3种乔木叶片中的Cd多存在于细胞壁或可溶性组分中,根系中的Cd多存在于细胞壁中,Cd在各组织的叶绿体、线粒体和细胞核等细胞器中分布较少.3种乔木叶片和根系中分别以移动性和毒性相对较低的HAc、NaCl提取态Cd分配比例最大.3种乔木各器官对Cd的积累能力与其叶片细胞中叶绿体与线粒体组分Cd占比有显著负相关关系,与叶片中HAc提取态Cd分配比例呈显著正相关性.     

控释掺混肥对麦玉轮作体系作物产量和温室气体排放的影响

为探究控释掺混肥一次性施肥对华北平原麦玉（冬小麦和夏玉米）轮作体系作物产量和温室气体排放的影响,于2020~2022年在德州市现代农业科技园区开展田间试验.冬小麦和夏玉米均设不施氮对照（CK）、农户习惯施氮（FFP）、优化施氮（OPT）、CRU1（包膜尿素与普通尿素在冬小麦和夏玉米上的掺混比例分别为5∶5和3∶7）、CRU2（包膜尿素与普通尿素在冬小麦和夏玉米上的掺混比例分别为7∶3和5∶5）共5个处理.对比分析了不同处理的作物产量、氮肥利用效率、施肥经济效益和温室气体排放的差异.结果表明,施氮可显著提高麦玉轮作系统单季和周年作物产量（P<0.05）.与FFP相比,CRU1和CRU2处理的夏玉米、冬小麦和周年产量分别提高了0.4%~5.6%、-5.4%~4.1%和-1.1%~3.9%（P>0.05）;氮肥吸收利用率、氮肥农学利用率和氮肥偏生产力分别提高了-8.6%~43.4%、2.05~6.24 kg·kg^-1和4.24~10.13 kg·kg^-1;周年净收益提高了0.2%~6.3%.施氮显著增加了麦玉轮作体系的土壤N₂O和CO₂的周年排放（P<0.05）,但对CH₄周年排放没有影响（第1年FFP处理除外）.CRU1和CRU2处理的土壤N₂O周年排放总量较FFP处理显著降低了23.4%~30.2%（P<0.05）.施氮显著增加了麦玉轮作体系的周年全球增温潜势（GWP）（P<0.05）,但各施氮处理通过提高作物产量降低了温室气体排放强度.与FFP相比,CRU1和CRU2处理的周年GWP降低了9.6%~11.5%（P<0.05）,周年温室气体排放强度（GHGI）降低了11.2%~13.8%（P>0.05）.综上所述,一次性减量施用控释掺混肥在减少氮肥和人工投入、提高作物产量、经济效益和降低温室气体排放方面具有积极作用,是促进华北平原粮食作物清洁生产的有效氮肥管理措施.     

叶片微观结构变化对其颗粒物滞纳能力的影响

叶片作为植物滞留大气颗粒物最主要的载体,其表面微观结构特征和粗糙度的差异是颗粒物滞纳能力的重要决定因素.叶片微观结构会随着生长(内部因素)以及环境污染强度(外部因素)发生变化,然而现有的粉尘喷洒模拟实验,一般持续时间较短,而微观结构变化响应具有明显的滞后性,其结果无法客观反映由内外因素作用引起的微观结构变化对颗粒物滞纳能力的影响.本研究利用新叶和老叶研究叶片生长,并选择自然状态下不同污染源条件研究污染强度,分析叶片表面微观结构的变化及其对颗粒物滞纳能力的影响.研究得到3种常绿树种(矮紫杉Taxus cuspidata var.、侧柏Platycladus orientalis和油松Pinus tabuliformis)的老叶滞纳TSP、 PM_(10)、 PM_(2.5)和PM_1量均高于新叶,随着叶片的生长其颗粒物滞纳量在增大,且新叶与老叶对不同粒径颗粒物的滞纳量间均存在极显著的差异.生长中叶片粗糙度Rq值的增大是老叶颗粒物滞纳能力增大的主要原因. 5个树种(侧柏、油松、国槐Sophora japonica、毛白杨Populus tomentosa和银杏Ginkgo biloba)TSP和PM_(10)滞纳量为重度污染区高于相对清洁区.而PM_(2.5)和PM_1滞纳量则是油松、银杏和侧柏为重度污染区高于相对清洁区,国槐和毛白杨为相对清洁区高于重度污染区.不同污染强度区域间叶片TSP、PM_(10)和PM_(2.5)滞纳量存在着极显著的差异,PM_1滞纳量也存在着差异.主要归因于与相对清洁区相比,重度污染区叶片的气孔指数降低,蜡质层退化,表面纹理和细胞边界更加不规则,绒毛变长,变硬,叶片微观结构的这些变化使得重度污染区叶片粗糙度Rq值高于相对清洁区,且叶片背面的增加较正面更明显.研究结果将为深入揭示叶片颗粒物滞纳能力的驱动因素,以及提出更科学地提升净化颗粒物功能的城市森林管理措施提供数据支持.     

The response of Trissolcus basalis to footprint contact kairomones from Nezara viridula females is mediated by leaf epicuticular waxes

Chemical footprints left behind by true bugs are perceived as contact kairomones by scelionid egg parasitoids. Female wasps encountering a contaminated artificial substrate display a characteristic arrestment posture, holding the body motionless and antennating the surface. In the system Nezara viridula (L.) and its egg parasitoid Trissolcus basalis (Wollaston), previous studies have shown that the kairomone mediating such behavior is part of N. viridula’s cuticular hydrocarbons (CHC) and furthermore that the wasp’s ability to discriminate host male and female footprints is mainly based on the presence/absence of nonadecane (nC₁₉). In this study, the effect of epicuticular waxes of leaves of broad bean, Vicia faba, on wasp responses to footprints of N. viridula females were investigated. Approximately 20% of T. basalis females displayed an arrestment posture when released on the adaxial leaf surfaces of broad bean plants with intact wax layer and without host chemical contamination; whereas ∼70% of wasps displayed the arrestment posture when intact leaves were contaminated by host female footprints. Adaxial leaf surfaces of broad bean plants dewaxed with an aqueous solution of gum arabic and afterwards contaminated by N. viridula females induced arrestment responses in about 10% of female wasps; the same percentage of arrestment (10%) was observed when the wasps were released on leaves contaminated by host females and subsequently dewaxed. The side of the polymer film that was appressed to the leaf surface, peeled from the contaminated leaves, induced an arrestment posture in about 95% of observed wasps. Scanning electron microscopy (SEM) revealed that the epicuticular waxes occurred as a film densely crystallized as irregularly shaped platelets with spherical granules randomly distributed. These findings demonstrated that epicuticular waxes of broad bean leaves can mediate the foraging behavior of T. basalis females by absorbing contact kairomones of the host.