朝鲜毛球蚧蜡泌物的超微形态与红外光谱特征

采用扫描电镜和红外光谱技术研究了朝鲜毛球蚧Didesmococcus koreanus在不同发育阶段蜡泌物的超微形态和化学成分。结果发现：该虫在低龄期的蜡泌物的形态是长丝状,到3龄和成虫期是由湿蜡凝结成不同大小的颗粒,块状和片状。雄虫蜡壳是薄蜡片构成,表面呈鱼鳞状凹凸。低龄期若虫蜡泌物的红外光谱特征与雌成虫的十分相似,说明二者所含的主要化学成分是相同的,雄虫和低龄若虫及雌成虫蜡壳萃取物的红外光谱的吸收峰型基本一致,但在1 240.7 cm^-1处出现一个中等强度的特征峰,这充分说明3种蜡泌物的有机化合物种类和结构一致,只是雄虫分泌物与另二者比较具有特征官能团,从而,利用该吸收峰可以区别出雄虫。此外,根据红外光谱特征分析,可以知道该虫蜡泌物的化学成分主要为长链脂肪酸、脂肪醇和一些带芳香环的化合物。     

瘤坚大球蚧蜡泌物的超微形态与红外光谱特征

采用扫描电镜和红外光谱技术研究了瘤坚大球蚧Eulecanium gigantea在不同发育阶段蜡泌物的超微形态和化学成分。结果发现：该虫在低龄期分泌湿蜡,最初在虫体背面凝结成晶体状的不同大小颗粒,接着连接成片状和块状构造,最后蜡质堆积形成龟背状蜡壳。蜡壳的各个板块与体壁上突起的腺孔分布区位置相对应。雄虫蜡壳与低龄期若虫蜡壳质地相同。雌成虫分泌的蜡质为长而卷曲的空心蜡丝。雌成虫背面和腹面蜡泌物的红外光谱特征说明二者所含的主要化学基团和成分是相同的。尽管雄虫蜡壳与雌虫的化学成分基本相似,但存在的官能团有明显差别,主要表现在雄虫蜡泌物光谱图上1736.3 cm^-1处出现两个吸收峰,而雌虫只有一个;在振动频率1 242.0 cm^-1～1 106.6 cm^-1出现3个C-O键振动峰,而雌虫的是一系列锯齿状长碳链-C-C-C-骨架振动峰。根据红外光谱特征分析,推测该虫蜡泌物的化学成分可能主要是由长链烃、长链脂肪酸、脂肪醇和某些带芳香环的化合物组成。     

柑橘真棉蚧蜡泌物的超微形态、红外光谱与化学成分特征

采用扫描电镜、红外光谱、气相色谱/质谱联用技术研究了柑橘真棉蚧Eupulvinariacitricola(Kuwana)(半翅目:蚧科)蜡泌物的超微形态、红外光谱和卵囊蜡质的化学成分特征。结果发现:该蚧雌虫背面腺体分泌湿蜡,在体表面形成薄的半透明蜡壳,背面蜡壳分为6个小区,表面由湿蜡凝结成片状和蜡块状构造。雌成虫产卵期由腹面多格腺分泌丝状蜡结成卵囊。雄若虫也分泌湿蜡,雄蛹的蜡茧薄,表面有浅的凹凸花纹。用雌成虫卵囊、背面蜡壳和雄茧的蜡质作红外光谱分析,它们的谱图具有共同的基本特征,吸收峰群分为5个区域:2900cm-1附近的3个强吸收峰组成的峰群是>CH2和—CH3的特征吸收峰;1800cm-1~1500cm-1之间的吸收峰群是羰基(>C=O)和C=C键的伸缩振动;1500cm-1~1400cm-1区域是>CH2和—CH3基团的吸收峰;1400cm-1~1000cm-1之间为饱和碳链—C—C—C—骨架振动。730cm-1附近为环状化合物的基团吸收峰群。由此确定它们的组成都是长碳链结构的脂肪酸、脂肪醇、烃类、酯类或带有环状结构的化合物。其主要区别在第2、3、4区吸收峰的形式、强度和数量,反映出基团的种类和数量不同。雌成虫卵囊蜡质甲酯化后GC/MS检测出7个组分(表1),全部为长链脂肪酸。未经甲酯化的蜡质检测出4类16个组分(表2),可分为长链烃、酸、醇、酯。第一类为饱和长链烃,5个组分,占总组分的38.38%;第二类是长链脂肪酸,包括直链饱和酸和不饱和酸共6个组分,占31.59%;第三类是直链饱和醇,占2.87%;第四类是酯类化合物,4个组分,占总组分的27.16%。     

角蜡蚧和日本龟蜡蚧蜡泌物的超微结构及化学成分分析

采用扫描电镜和气相色谱/质谱联用技术研究了角蜡Ceroplastes ceriferus (Fabricius) 和日本龟蜡蚧C. japonicus Green蜡泌物的超微结构及化学成分。结果表明,这2种蜡蚧分泌蜡质和形成蜡壳的过程基本相似。在1、2龄期分泌的蜡质为“干蜡”,蜡壳为星芒状,虫体周缘的蜡芒均为2大节,与其2个龄期发育相对应,每一个大节又分为若干小节。同时,虫体背面中央蜡质堆积成帽状,也分为均匀的多层。由此说明泌蜡过程具有节律性。虫体周缘与蜡芒对应的突起区上分布着密集的刻点状腺孔,每一个腺孔分泌1根蜡丝,这在以往玻片标本中是观察不到的。雌性第3龄幼虫和成虫期,虫体分泌“湿蜡”,形成龟背状蜡壳,泌蜡腺孔主要为三格腺和四格腺。在肛突区发现了密集的泌蜡腺孔,排列为纵条纹状。从角蜡蚧蜡泌物甲酯化处理样品中检测到14个组分,从直接测试 (未经甲酯化处理) 样品中检测到14个组分;而从日本龟蜡蚧则分别检测到10个组分和25个组分。它们的主要成分是一系列高级的长链饱和与不饱和的烃、脂肪酸、脂肪醇、酯类、醛类以及杂环、多环或大环状化合物。对它们可能的生物生态学功能进行了讨论。     

蚧虫蜡泌物的化学研究进展

总结了国内外对蚧虫蜡泌物及其化学成分的研究进展 ,内容包括蜡泌物形成介壳的主要类型 ;蜡泌物的化学研究方法及已涉及的种类 ;蜡泌物的主要化学组成 ,并对 5类物质 ,即蜡、烃类、树脂或萜类、色素类、内蜜露作了重点叙述。最后 ,讨论了研究蚧虫蜡泌物的化学成分具有的意义和应用前景 ,包括蜡泌物作为生物资源的利用 ;以蚧虫作为农林、果树和花卉业的重要害虫 ,针对蜡泌物的特点研制相应的新型杀虫剂 ;利用蜡泌物的化学信息素对天敌的诱导作用 ,开展蚧虫生物防治 ;利用蜡泌物作为化学分类性状的应用等。     

南洋臀纹粉蚧雌成虫主要器官及其蜡泌物的扫描电镜观察

为明确南洋臀纹粉蚧Planococcus lilacinus(Cockerell)雌成虫及其蜡泌物的结构特征,利用扫描电镜观察该虫体表主要器官、蜡质及泌蜡腺体的超微结构.结果表明:南洋臀纹粉蚧雌成虫外覆白色粉状厚蜡被,体缘具18对蜡棒,触角8节、口器和足发达且分布有不同长度的毛形和刺形感受器,眼为单眼,腹脐和背孔唇形、发达;体表蜡质包含带状蜡丝、空心管状蜡丝和月牙形蜡丝,由三格腺和刺孔群分泌的带状蜡丝大量分布于整个虫体,由管状腺分泌的空心管状蜡丝主要分布于虫体腹部腹面和体缘,由多格腺分泌的月牙形蜡丝主要分布于虫体腹部腹面.研究结果初步揭示了南洋臀纹粉蚧雌成虫体表主要器官、蜡质及泌蜡腺体的超微结构特征,可为研究该虫搜索寄主、寻找配偶、群集为害、抵御逆境和传播扩散等行为活动提供支持.     

枣球蜡蚧雄虫不同发育期的形态特征

采用光学显微镜研究了枣球蜡蚧Eulecaniumgiganteum (Shinji)雄虫在不同发育期的形态特征。结果表明 :该虫雄性完成其生活史需经历初孵若虫、固定若虫、预蛹和蛹、雄成虫 4个阶段。初孵的 1龄若虫为扩散活动期 ,虫体具有发达的单眼、触角和 3对胸足 ,便于寻找寄生场所 ,但泌蜡腺体很少。 1龄后期和 2龄若虫为固定取食期 ,虫体缘毛粗大 ,泌蜡腺体很多 ,蜡泌物在虫体背面堆积成龟背状蜡壳 ,自我保护性很强。预蛹和蛹不再取食 ,虫体隐藏在白色的半透明蜡壳内。与若虫相比 ,体形变化很大 ,预蛹出现翅芽 ,而其它各器官退化 ,眼无 ,触角和足短小且分节不显。到蛹期 ,翅芽、触角和足明显长大 ,并出现感觉毛。成虫期为活动交配期 ,头部出现发达的 5对单眼 ,触角 1 0节 ,密布各种刚毛等感觉器。前翅和足发育完好。     

昆虫病原真菌对日本龟蜡蚧蜡泌物的降解作用

[目的]为了研究昆虫病原真菌感染蚧虫过程中对其蜡泌物的降解作用.[方法]本文选择3种虫生真菌的4个菌株即,蜡蚧霉Lecaniciliium lecanii的菌株V3.4504和V3.4505、球孢白僵菌Beauveria bassiana菌株FDB01和绿僵菌Metarhizium anisopliae菌株TSL06,以日本龟蜡蚧Ceroplastes japonicus Green(昆虫纲:半翅目:蚧总科)雌成虫的蜡泌物作为无机盐培养液中的唯一碳源,研究各菌株在该无机盐培养液中的生长情况、酶活变化和对蜡泌物的降解作用.[结果]在上述培养液中,4株病原真菌都能以日本龟蜡蚧的蜡泌物作为其营养碳源,进行生长繁殖,产生酶类物质,对蜡质造成降解.菌株V3.4504和V3.4505在无机盐培养液中多以芽管的形态存在,而菌株FDB01和TSL06多以附着胞的形式存在;在7天的培养过程中,菌株V3.4504、V3.4505、FDB01、TSL06的脂肪酶活性最高值分别为(0.128±0.017) U/mL、(0.056±0.002) U/mL、(0.124±0.011) U/mL、(0.149±0.005) U/mL,不同菌株之间的脂肪酶活性有显著差异;4菌株脱氢酶活性分别为(0.075±0.003) U/mL、(0.074±0.003) U/mL、(0.061 ±0.04) U/mL、(0.066±0.002) U/mL,它们之间的差异没有达到显著水平;4菌株对蜡泌物的降解率分别为(18.20±0.019)％、(11.00±0.011)％、(15.4±0.017)％、(23.10±0.031)％;在菌的作用下,蜡泌物的结构变得松脆,表面出现许多小孔洞,并有白色附着物.用扫描电镜观察到了菌丝在蜡质上的附着和穿刺.[结论]昆虫病原真菌可以降解日本龟蜡蚧蜡泌物的化学成分(主要是长链脂肪酸等多种长碳链化合物以及组成“内蜜露”的多种糖类和氨基酸)作为自己的营养碳源,并使蜡泌物的物理结构发生改变,这是病菌打破蜡壳屏障,成功入侵蚧虫的关键原因.菌株分泌的脂肪酶和脱氢酶参与了降解作用,其中脂肪酶发挥了更为关键的作用.4菌株中对蜡质的降解率依次为TSL06＞ V3.4504＞FDB01＞V3.4505.     

柿白毡蚧蜡泌物的超微结构与蜡壳的形成

采用扫描电镜技术研究了柿白毡蚧Asiacornococcus kaki(Kuwana)泌蜡腺体、蜡泌物的超微结构与蜡壳形成过程.结果发现,蜡壳形成分3个阶段,即泌蜡发生期、泌蜡增长期和蜡囊形成期,由3种腺体分泌的蜡质构成.锥刺是泌蜡的主要器官,其分泌的粗蜡管形成蜡壳的框架.管腺分泌空心细蜡丝,与框架蜡管紧密交织在一起.单孔腺分泌的细小蜡丝散布虫体表面.雄茧扁平,由空心长丝状蜡编织形成.     

蜡蚧轮枝菌分生孢子在不同虫态棕尾別麻蝇体表的附着能力及与寄主体表结构的关系

【目的】为解释蜡蚧轮枝菌Lecanicillium lecanii对棕尾别麻蝇Boettcherisca peregrina成虫、蛹和幼虫等 3种虫态的致病性差异,研究分析了蜡蚧轮枝菌L. lecanii分生孢子在3种虫态体表的附着能力及与寄主体表结构的关系。【方法】采用血球计数板计数法测量蜡蚧轮枝菌分生孢子在棕尾別麻蝇B. peregrina成虫、蛹和幼虫体表的附着数量,并利用扫描电子显微镜等显微技术观察供试虫体体壁外长物分布情况以及附着分生孢子情况。【结果】蜡蚧轮枝菌分生孢子在棕尾別麻蝇3种虫态上的附着数量差异显著(P=0.0001),成虫附着孢子数量为(1.35±0.12)×10⁶个/头,而蛹和幼虫分别为(0.57±0.09)×10⁶个/头和(0.45±0.06)×10⁶个/头。成虫周身微毛上均有孢子附着;整个蛹体仅棘刺底部呈“绳索状”的褶皱处可发现有孢子的附着;幼虫的体表未发现有孢子的附着。【结论】蜡蚧轮枝菌分生孢子在棕尾別麻蝇成虫、蛹、幼虫体表的附着能力与寄主体表结构有密切关系,是蜡蚧轮枝菌对该虫不同虫态间存在致病差异的原因。     

The hinged back plate mechanism in glassy wax tests of New Zealand male soft scale insects (Hemiptera: Coccoidea: Coccidae)

Male scale insects (Hemiptera: Coccoidea) undergo a metamorphosis of the neometabola type, from scale-like nymph through prepupa and pupa to winged adult. The nymphal instar before prepupa secretes a waxy protective covering that remains in place throughout metamorphosis and these covers are characteristic of each family of scale insects. Most scale insect families (e.g. mealybugs, eriococcids, diaspidids) have rather loosely woven male covers, but male nymphs in the family Coccidae (soft scales) construct more rigid, glassy wax tests, which need a special mechanism for adult emergence. In the New Zealand male soft scales, a suture across the posterior quarter of the test enables the back plate to flex at a pair of hinges, to be raised up off the substrate, and so allow egress. The waxy back plate hinges are secreted by groups of tubular ducts on the abdominal dorsum of 2nd-instar males, during construction of the test. Scanning electron micrographs (SEMs) show the detail and diversity of hinge types. The wax tests of most New Zealand Coccidae, both female and male, are apparently unique in that they are constructed in rows of hexagonal plates, separated by sutures, however in the male test, the sutures are all fused except for the back plate suture. The two species in the endemic New Zealand genus Pounamococcus have male tests more like those of species in the Australian genus Austrolecanium.     

Observation of an anisotropic texture inside the wax layer of insect cuticle

The outermost part of insect cuticles is very often covered with wax, which prevents desiccation and serves for chemical communication in many species. Earlier studies on cuticular waxes have mainly focused on their chemical composition revealing complex mixtures of lipids. In the absence of information on their physical organization, cuticular waxes have been considered isotropic. Here we report the presence of parallel stripes in the wax layer of the carapace of the scarab beetle, Chrysina gloriosa, with a textural periodicity of ca. 28 nm, as revealed by electron microscopy of transverse sections. Observations at oblique incidence argue for a layered organization of the wax, which might be related to a layer-by-layer deposition of excreted wax. Our findings may lay the foundation for further studies on the internal structure of cuticular waxes for other insects.     

Evolutionary relationships of flavobacterial and enterobacterial endosymbionts with their scale insect hosts (Hemiptera: Coccoidea)

Flavobacteria and Enterobacteriaceae have been previously reported as scale insect endosymbionts. The purpose of this work was twofold: first, to screen different scale insect families for the presence of these endosymbionts by PCR analyses and second, to elucidate the history of cophylogeny between these bacteria and the insects by analysing a portion of 16S rRNA and 18S rRNA gene sequences by two reconciliation tools, CoRe‐PA and Jane. From a survey of 27 scale insects within seven families, we identified Flavobacteria and Enterobacteriaceae as coexisting in ten species that belong to the Ortheziidae, Monophlebidae, Diaspididae and Coccidae families, and we frequently found two closely related enterobacteria harboured in the same individual. Analyses performed with CoRe‐PA and Jane suggest that Flavobacteria from the scale insects analysed have a unique origin, except for Candidatus Brownia rhizoecola (Flavobacteria of Pseudococcidae, Phenacoccinae), which seems to come from a nonscale insect. Nevertheless, cospeciation between Flavobacteria and scale insects is suggested only within the families Monophlebidae, Ortheziidae and Diaspididae, and host switches seem to have occurred from the ancestors of Monophlebidae and Ortheziidae to insects from families Coccidae, Lecanodiaspididae, Eriococcidae and Pseudococcidae. Our analyses suggest that Enterobacteriaceae underwent more evolutionary events (losses, duplications and host switches), and their phylogenies showed a lower proportion of congruent nodes between host and bacteria, indicating a more relaxed relationship with scale insects compared with Flavobacteria.     

Foliar cuticular waxes of cultivated species and varieties of Coffea

The cuticular waxes of leaves of Coffea arabica cv. ‘Catuaí Vermelho’, C. arabica cv. ‘Obatã’, Coffea canephora cv. ‘Apoatã’, Coffea racemosa and two hybrids between C. arabica and C. racemosa were extracted by rapid washing of the surface with chloroform. The waxes were fractionated by thin layer chromatography over silicagel. The fractions of the constituent classes were characterized by infrared spectroscopy and the distribution of the homologs of the n-alkanes and n-primary alcohols was determined by GC/MS and GC/FID. Among the samples analyzed, leaves of C. racemosa have the highest content of foliar wax (22.9 μg cm⁻²). Most samples contain either n-alkanes (C. canephora and C. racemosa) or n-primary alcohols (C. arabica) as predominant wax constituents. The distribution of n-alkanes allowed the distinction of C. racemosa from the other samples; the distribution of alcohols allowed the distinction of the three species. The two hybrids have waxes similar to the wax of C. arabica.     

Spruce budworm feeding and oviposition are stimulated by monoterpenes in white spruce epicuticular waxes

Monoterpenes, source of the distinctive odor of conifers, are generally considered plant defensive compounds. However, they are also known to act as long‐range insect attractants, as they are volatile and permeate forest airspaces. Moreover, they are lipid soluble and can be absorbed into plant epicuticular waxes. We test their role in short‐range host plant choice by both adult females and larvae of a folivorous forest pest (Choristoneura fumiferana). We conducted laboratory assays testing the responses of Eastern spruce budworm to an artificial monoterpene mix (α‐pinene, β‐pinene, limonene, myrcene) and to white spruce (Picea glauca) epicuticular waxes in closed arenas. Ovipositing females preferred filter paper discs treated with P. glauca waxes to controls, and preferred the waxes + monoterpenes treatment to waxes alone. However, females showed no preference between the monoterpene‐treated disc and the control when presented without waxes. Feeding larvae prefered wax discs to control discs. They also consumed discs treated with realistic monoterpene concentrations and wax preferentially over wax‐only discs, but showed no preference between extremely high monoterpene concentrations and wax‐only controls. In an insect‐free assay, P. glauca epicuticular wax decreased monoterpene volatilization. These results suggest that P. glauca waxes and realistic concentrations of monoterpenes are stimulatory to both egg‐laying females and feeding larvae, and that their effects are synergistic.