长蝎蛉幼期形态附生物学记述

【目的】蝎蛉科(Panorpidae)是长翅目(Mecoptera)最大的科,是重要的生态指示昆虫。然而,由于对环境条件要求苛刻,饲养困难,其幼期研究很不充分。【方法】本研究通过人工饲养成虫获得了长蝎蛉Panorpa macrostyla Hua的卵、幼虫和蛹等全部虫态,运用光学显微镜和扫描电子显微技术观察了其超微形态,并简要记载了其生物学特性。【结果】长蝎蛉每年发生1代,成虫发生于6月末至8月初。卵椭球形,卵壳表面覆盖一层隆起的网状结构。幼虫蠋型,具3对分4节的胸足和8对不分节的腹足;头壳高度骨化,具1对由26个小眼组成的复眼和1对3节的触角,口器咀嚼式;腹部第1-9节背面具有成对的背毛突,第10节仅有1根背毛突,腹部末端具有一个可伸缩的吸盘;呼吸系统为周气门式,具1对前胸气门和8对腹气门。幼虫共4个龄期,以预蛹期在土室内越冬。蛹为强颚离蛹,外形接近成虫,雄蛹腹部末端膨大。【结论】基于幼虫形态特征,长蝎蛉明显区别于新蝎蛉属Neopanorpa、华蝎蛉属Sinopanorpa、双角蝎蛉属Dicerapanorpa以及单角蝎蛉属Cerapanorpa幼虫。然而,长蝎蛉幼虫头部刚毛L2和SO2,腹部末节刚毛D2,SD1和SD2端部均膨大呈棒状,与蝎蛉属Panorpa其他种类区别明显,表明长蝎蛉的属级地位需要进一步研究。     

中国大巴山蚊蝎蛉属一新种(长翅目,蚊蝎蛉科)

记述采自中国大巴山的蚊蝎蛉属1新种,周氏蚊蝎蛉Bittacus Choui sp.nov.,模式标本保存于西北农林科技大学昆虫博物馆,并通过人工饲养获得卵、幼虫和蛹等所有虫态,提供了成虫、卵、幼虫和蛹等虫态照片,绘制了雌雄外生殖器特征图,简要报道了新种的生物学和生活史.     

广重粉蛉对烟粉虱的捕食作用研究

【目的】广重粉蛉Semidalis aleyrodiformis(Stephens)是烟粉虱Bemisia tabaci(Gennadius)的重要天敌昆虫之一,为了明确其控制潜能,本文研究了广重粉蛉对烟粉虱的捕食作用。【方法】在室内温度(26±1)℃,相对湿度75%±5%,光照周期L∶D=14∶10条件下,对广重粉蛉幼虫捕食烟粉虱各个虫态的捕食作用进行研究。并且评估了广重粉蛉幼虫对烟粉虱卵、广重粉蛉成虫对烟粉虱若虫和伪蛹的捕食功能反应模型,同时,对广重粉蛉成虫捕食烟粉虱卵的干扰反应方程进行了拟合。【结果】广重粉蛉幼虫对烟粉虱的捕食量随着广重粉蛉龄期的增大而增大。广重粉蛉幼虫对烟粉虱卵的功能反应和广重粉蛉成虫对烟粉虱各个虫态的捕食功能反应都呈HollingⅡ型。随着广重粉蛉龄期的增加,广重粉蛉对烟粉虱卵的寻找效率(a)逐渐增加,处置时间(Th)依次缩短;而广重粉蛉成虫对不同龄期烟粉虱的功能反应是随着猎物龄期的增加,寻找效率逐渐降低,处置时间(Th)依次延长。广重粉蛉自身密度方程为E=0.127 9×P-0.317 3,干扰系数为0.317 3。【结论】研究表明,广重粉蛉4龄幼虫和雌成虫对烟粉虱有较好的捕食作用,控害潜力最大。     

2种辉蝽的精巢和染色体研究(半翅目:蝽科)

通过探讨中国蝽科Pentatomidae辉蝽属Carbula的红角辉蝽Carbula crassiventris(Dallas,1849)和北方辉蝽C.putoni(Jakovlev,1876)的精巢形态和染色体的核型及减数分裂行为,为蝽科昆虫的细胞分类学提供新资料。采用显微形态解剖法和染色体制片法对其精巢和染色体进行观察。结果表明:2种精巢的位置、外被颜色、形状及精巢叶的数目都一致;染色体组成均为2n(♂)=14(12A+XY),具有X-Y性别决定机制。在减数分裂过程中,常染色体前减数分裂,性染色体后减数分裂且无交叉;在中期-Ⅱ,常染色体排列成环状而性染色体在环中央形成假二价体。但是,2个物种在弥散期常染色体的去固缩程度,终变期常染色体双交叉的个数及中期-Ⅰ常染色体和性染色体的排列方式都各不相同。本文证实了蝽科昆虫的减数分裂行为在不同属间、种间可不相同,而且具有一定的属、种间特异性;同时为精巢在蝽类昆虫分类中的作用提供新的资料。     

大双角蝎蛉幼虫复眼超微结构及其在全变态类幼虫侧单眼演化中的意义

【目的】长翅目(Mecoptera)是全变态类昆虫中唯一在幼虫期具有复眼而无侧单眼的类群,是研究昆虫复眼与侧单眼之间演化关系的理想材料。本研究旨在阐明长翅目幼虫复眼的结构特征,为探讨长翅目幼虫复眼与其他全变态类幼虫侧单眼之间的进化关系提供依据。【方法】本研究运用光学显微镜、扫描和透射电子显微镜技术观察了蝎蛉科(Panorpidae)大双角蝎蛉Dicerapanorpa magna(Chou)幼虫复眼的超微结构,并依据其结构特征对长翅目幼虫复眼在全变态类幼虫侧单眼演化中的意义进行了探讨。【结果】结果表明,大双角蝎蛉幼虫复眼属于并列像眼,由50多个小眼组成。小眼由1个角膜、1个晶体、8个视网膜细胞、2个初级色素细胞和数个次级色素细胞等组成。视网膜细胞分为4个远端细胞和4个近端细胞。远端视网膜细胞的视小杆向上延伸包裹着晶体的基部,使视杆末端呈漏斗状。【结论】分层的视网膜细胞和漏斗状的视杆很可能是长翅目幼虫复眼的共有祖征。这两个特征不存在于长翅目成虫复眼中,但存在于许多渐变态类昆虫中。由此推测,长翅目幼虫复眼可能与渐变态类昆虫的复眼存在同源关系。我们认为,长翅目幼虫独有的复眼很可能是全变态类昆虫的祖征,其他全变态类幼虫的侧单眼可能是由复眼演化来的。     

食蚜瘿蚊全虫态形态记述

【目的】基于实验室饲养的食蚜瘿蚊Aphidoletes aphidimyza (Rondani)进行个体发育的形态特征描述。为食蚜瘿蚊的鉴定提供基本信息。【方法】在野外采集幼虫,温度(25±1)℃、相对湿度65%±5%、光照16 L∶8 D的室内条件下饲养获得食蚜瘿蚊卵、幼虫、蛹和成虫的全部虫态。通过数码采集和电子显微镜详细描述了各虫态的发育特征。【结果】食蚜瘿蚊卵的发育历期为2 d,幼虫期有3个龄期,发育历期5-8 d,蛹期7-10 d以及成虫期3-4 d。【结论】食蚜瘿蚊个体发育特征对食蚜瘿蚊的鉴定和分类有指导意义。     

不同虫态及虫龄大草蛉与七星瓢虫之间的集团内互作

【目的】为明确新疆棉田棉蚜 Aphis gossypii 捕食性天敌之间的集团内捕食效应及其对蚜虫数量的控制作用。【方法】本研究以优势天敌昆虫大草蛉 Chrysopa pallens 和七星瓢虫 Coccinella septempunctata 为对象,以棉蚜为猎物,在温室中利用盆栽棉花,首先观察了2种天敌昆虫之间各虫态及虫龄配对的19个处理在无蚜植株上共存24 h后的存活数,然后观察了2种天敌昆虫配对处理下棉苗上棉蚜数量随时间的变化趋势。【结果】在无蚜棉株上2种捕食性天敌昆虫共存24 h后的存活结果表明：（1）在发育阶段相同的配对组合中,若是成虫则均存活,若是１龄幼虫则大草蛉存活较多,若是末龄幼虫则七星瓢虫存活较多;（2）在有卵的组配中,除七星瓢虫卵不被大草蛉成虫所捕食外,其他5个组配处理中卵均被捕食;（3）在有蛹的配对组合中,除七星瓢虫蛹被大草蛉末龄幼虫捕食外,其他处理下蛹均不被捕食;（4）在成虫与幼虫的配对组合中,七星瓢虫成虫捕食较多的大草蛉1龄幼虫,但不捕食大草蛉末龄幼虫,而大草蛉成虫与七星瓢虫1龄或末龄幼虫之间不发生捕食;(5）在不同龄期幼虫的配对组合中,大草蛉末龄幼虫捕食七星瓢虫1龄幼虫,而七星瓢虫末龄幼虫捕食大草蛉1龄幼虫。在有蚜植株上2种捕食性天敌共存对棉蚜数量具有不同的控制作用：（1）2种捕食昆虫的幼虫各自单独存在（对照）下,蚜虫密度随时间而降低;（2）大草蛉幼虫与七星瓢虫幼虫或成虫配对处理下,棉蚜密度随时间而增大;（3）大草蛉成虫与七星瓢虫幼虫或成虫配对处理下,棉蚜密度随时间而减小。【结论】研究结果说明,大草蛉与七星瓢虫之间存在集团内捕食,但２种天敌共存对棉蚜的控制作用取决于大草蛉虫态, 若大草蛉为幼虫,可使蚜虫密度增大,若为成虫,则使蚜虫密度减小。     

紫竹梅的减数分裂与核型分析

以紫竹梅根尖和花药为材料,分析鸭跖草科紫竹梅的染色体组型,并观察花粉母细胞减数分裂过程中的染色体行为。紫竹梅体细胞染色体数目为24,由12对中着丝粒染色体组成,核型公式为2n=2x=24m。花粉母细胞减数分裂正常,在第一次分裂中期观察到12个二价体,与观察到的体细胞染色体数目互相印证。     

蝎蛉科与蚊蝎蛉科昆虫触角感器超微形态比较

触角是昆虫重要的感觉器官,其感觉功能主要是通过其上的各类感器来实现的。本文以染翅蝎蛉Sinopanorpa tincta(Nav偄s)和中华蚊蝎蛉Bittacus sinensis Walker为代表,采用扫描电子显微镜观察了蝎蛉科Panorpidae和蚊蝎蛉科Bittacidae触角感器的类型及其超微结构,并简要讨论了各种感器的功能。结果显示:染翅蝎蛉触角上共发现7种感器,分别为短刺形感器、Bhm氏鬃毛、毛形感器、短毛形感器、锥形感器、刺形感器、和微毛形感器。中华蚊蝎蛉触角上也发现7种感器,分别为Bhm氏鬃毛、芽形感器、毛形感器、刺形感器、畸形毛感器、腔锥感器和钟形感器。蚊蝎蛉触角与蝎蛉的最大区别是着生有大量的腔锥感器,初步推测众多的腔锥感器可能与蚊蝎蛉对湿度的高度敏感有关。     

线虫Distolabrellus veechi的生殖系统及配子发生

以线虫Distolabrellus veechi的卵巢和精巢为材料,用甲醇固定,DAPI荧光染料对细胞核进行染色,通过Normaski荧光显微镜对其生殖系统结构、性细胞染色体数目、体细胞染色体数目进行了观察.结果显示了该线虫雌虫和雄虫生殖细胞减数分裂Ⅰ前期的细胞核的变化特征;减数分裂Ⅰ前期丝球期雌、雄生殖细胞的二价体数目均为6;卵细胞染色体数目为6,精细胞染色体数目为5或6,其性别决定机制为XX/X0型;体细胞染色体数目为11(雄虫)或12(雌虫)[动物学报 54(3):500-509,2008].     

A new approach to the auchenorrhyncha (Hemiptera, Insecta) cytogenetics: chromosomes of the meadow spittlebug Philaenus spumarius (L.) examined using various chromosome banding techniques

The karyotype of the meadow spittlebug Philaenus spumarius (L.) was studied using conventional chromosome staining, C- and AgNOR- banding, and fluorescent CMA3- and DAPI- techniques. This is the first report on differential staining of the holocentric chromosomes of Auchenorrhyncha. The karyotype of Ph. spumarius includes 2n = 22 + XX/X0. The autosomal pair 1 is large and carries a gap in every homologue. After silver staining, NORs were revealed in both this chromosome pair and a middle-sized pair, most likely 6 or 7. In spermatocyte meiosis, the majority of bivalents formed one chiasma each. The bivalent 1 showed from 1 to 4 chiasmata, the value of 1 or 2 being prevalent. Two further bivalents also showed two chiasmata in some cells. After C-banding, terminal and interstitial dot-type C-heterochromatic blocks were revealed in the chromosomes. In 4 of 11 studied males, the autosomal pair 1 was polymorphic for an extra segment attached to one of the homologues. The segment consisted of both heterochromatic and euchromatic portions. No defined signals were observed in any chromosome treated with DAPI. After CMA3- staining, bright fluorescent signals were obtained in the NOR-bearing chromosomes, suggesting GC-rich DNA bound to the NORs.     

C-Banding/DAPI and in situ hybridization reflect karyotype structure and sex chromosome differentiation in Humulus japonicus Siebold & Zucc

Japanese hop (Humulus japonicus Siebold & Zucc.) was karyotyped by chromosome measurements, fluorescence in situ hybridization with rDNA and telomeric probes, and C-banding/DAPI. The karyotype of this species consists of sex chromosomes (XX in female and XY1Y2 in male plants) and 14 autosomes difficult to distinguish by morphology. The chromosome complement also shows a rather monotonous terminal distribution of telomeric repeats, with the exception of a pair of autosomes possessing an additional cluster of telomeric sequences located within the shorter arm. Using C-banding/DAPI staining and 5S and 45S rDNA probes we constructed a fluorescent karyotype that can be used to distinguish all autosome pairs of this species except for the 2 largest autosome pairs, lacking rDNA signals and having similar size and DAPI-banding patterns. Sex chromosomes of H. japonicus display a unique banding pattern and different DAPI fluorescence intensity. The X chromosome possesses only one brightly stained AT-rich terminal segment, the Y1 has 2 such segments, and the Y2 is completely devoid of DAPI signal. After C-banding/DAPI, both Y chromosomes can be easily distinguished from the rest of the chromosome complement by the increased fluorescence of their arms. We discuss the utility of these methods for studying karyotype and sex chromosome evolution in hops.     

The meiotic structure and behavior of the strongly heteromorphic X/Y sex chromosomes of neotropical plethodontid salamanders of the genus Oedipina

Plethodontid salamanders in the genus Oedipina are characterized by a strongly heteromorphic sex-determining pair of X/Y chromosomes. The telocentric X chromosome and the subtelocentric Y chromosome are clearly distinguished from the autosomes and their behavior during meiosis can be sequentially followed in squash preparations of spermatocytes. In Oedipina the sex chromosomes are not obscured by an opaque sex vesicle during early meiotic stages, making it possible to observe details of sex bivalent structure and behavior not directly visible in other vertebrate groups. The sex chromosomes can first be distinguished from autosomal bivalents at the conclusion of zygotene, with X and Y synapsed only along a short segment at their non-centromeric ends, forming a bivalent that contrasts sharply with the completely synapsed autosomes. During pachytene, the XY bivalent becomes progressively shortened and more compact, disappearing as a visible structure when pachytene progresses into the diffuse stage of male meiosis. Diplotene bivalents gradually emerge from the diffuse nuclei, presumably by the return of the loops of chromatin into their respective chromomeres. During early diplotene, the X/Y bivalent is clearly visible with a single chiasma within the synapsed segment. This chiasma is terminalized by first meiotic metaphase with the X and Y appearing either in end-to-end synaptic contact or as univalents separated at opposite poles relative to the equatorially distributed autosomal bivalents. In C-banded preparations, the Y is entirely heterochromatic while the X contains a large centromeric C-band and another block of heterochromatin located at the telomeric end, in the region of synapsis with the Y. We find no cytological evidence of dosage compensation, such as differential staining of the X chromosomes or Barr bodies, in mitotic or interphase cells from female animals.     

Heterochromatin (C-bands) in somatic and male germ cells in three species ofMicrotinae

The C-banding patterns in the chromosomes ofMicrotus oeconomus, M. arvalis andM. ochrogaster demonstrate differences in the amount and distribution of heterochromatin. Autosomal centromeric heterochromatin appears as conspicuous blocks or as small dots, and in several chromosomes no heterochromatin was detected; interstitial heterochromatin was observed in one autosome pair ofM. ochrogaster. The sex chromosomes also demonstrate differences in the C-banding pattern. InM. oeconomus, the X chromosome exhibits a block of centromeric heterochromatin which is larger than that of the autosomes; this characteristic helps to recognize the X chromosomes in the karyotype. InM. arvalis no heterochromatin was appreciated in the sex chromosomes. The Y chromosomes ofM. ochrogaster andM. oeconomus are entirely heterochromatic. During male meiosis heterochromatin shows condensation, association and chiasma prevention; the sex chromosomes pair end to end in the three species. At pairing, the Y chromosome ofM. arvalis is despiralized, but it appears condensed again shortly before separation of the bivalent.     

Mammalian sex chromosomes

The X and Y chromosomes of the musk shrew are the two largest in the complement and they regularly form a single chiasma during meiosis. This chiasma is located in the short arms of the X and Y, both of which show partial C-banding at meiosis. The in vitro incorporation of 5-bromodeoxyuridine/tritiated thymidine during late S reveals that the non-C-band region of the Y finishes replication later than the C-band positive heterochromatin. During meiosis, the sex bivalent opens out early in pachytene to reveal a single chiasma which persists until late metaphase-I. In surface-spread, silver-stained meiocytes, the sex bivalent morphology changes from a phase of extensive pairing to one which includes a visible chiasma through a brief diffuse stage. Observations on C-banded meiocytes show a shift in the sex pair from a C-band positive to a negative state as compared to their corresponding somatic pattern. Comparable changes are also observed in the sex bivalents of other mammals which undergo a chiasmatic exchange. This suggests that in addition to pairing homology, an alteration in the chromatin configuration may be necessary for crossing over to occur between the sex chromosomes.     

Heteromorphic sex chromosome system with an exceptionally large Y chromosome in a catfish Steindachneridion sp. (Pimelodidae)

The chromosomes and banding patterns of Steindachneridion sp., a large catfish (Pimelodidae), endemic to the Igua?u River, Brazil, were analyzed using conventional (C-, G-banding) and restriction enzyme banding methods. The same diploid number (2n = 56) as in other members of the genus and the family was found but the karyotype displayed an XX/XY sex chromosome system. The X chromosome was the smallest submetacentric, while the Y was the largest chromosome in the karyotype. Meiotic analysis showed 27 autosomal bivalents plus one heteromorphic XY bivalent during spermatogenesis. Sex chromosomes had no particular pattern after C-banding but G- and restriction enzyme bandings showed specific banding characteristics. The present finding represents the first report of a well-differentiated and uncommon sex chromosome system in the catfish family Pimelodidae.     

Cytogenetics of Manihot esculenta Crantz (cassava) and eight related species

Thirty-nine cultivars of cassava and eight related wild species of Manihot were analyzed in this work for number, morphology and size of chromosomes, prophase condensation pattern and the structure of the interphase nucleus. In four accessions, the chromosome size was measured and in some others, the number of secondary constrictions, meiotic behavior, C-band pattern, CMA/DAPI bands, nucleoli number and the location of 5S and 18S-5.8S-28S rDNA sites were also observed. All investigated accessions showed a similar karyotype with 2n = 36, small metacentric to submetacentric chromosomes. Two pairs of terminal secondary constrictions were observed in the chromosome complement of each accession except Manihot sp. 1, which presented two proximal secondary constrictions. The prophase chromosome condensation pattern was proximal and the interphase nuclei structure was areticulate to semi-reticulate. The meiosis, investigated in seven cultivars and four wild species, was regular, displaying 18 bivalents. C-banding revealed heterochromatin in 9 or 10 chromosomes. The analysis with fluorochromes frequently showed four chromosome pairs with a single CMA+ terminal or subterminal band and a few other chromosomes with DAPI+ unstable bands. Six 45S rDNA sites were revealed by FISH, which seemed to colocalize with six CMA+ bands. Only one chromosome pair presented a 5S rDNA site. The maximum nucleoli number observed per nucleus was also six. These data suggest that all Manihot species present a very similar chromosome complement.     

Chiasma frequency,distribution and interference maps of mouse autosomes

Chiasma frequencies were analysed and chiasma positions measured in diakinesis/metaphase I autosomal bivalents from oocytes and spermatocytes of F₁ hybrid C3H/HeH×101/H mice. Twenty chromosome size ranks, including the presumptive X bivalent, could be distinguished in oocytes, and nineteen autosomal ranks plus the XY pair spermatocytes. Overall, mean cell chiasma frequencies of the two sexes did not differ significantly once the contribution of the presumptive X bivalent and the XY pair were taken into account. Sex related differences in chiasma distribution patterns were evident, however. In monochiasmate bivalents, the chiasma was most commonly located interstitially in oocytes while in spermatocytes it could be either interstitial or distal. In dichiasmate bivalents, the chiasmata tended to be more centrally located in oocytes than in spermatocytes. Minimum inter-chiasma distances did not appear to show any great variation in chromosome pairs of different sizes, however, mean inter-chiasma distances did increase with the bivalent length. The minimum-inter chiasma distance data suggest that chiasma interference is complete over a chromosomal segment equating to approximately 60 Mb. Measurement of the positions of chiasmata along chromosome arms open up the possibility of producing chiasma-based genetic maps for all the autosomes of the mouse.     

Karyotype,heterochromatin content and meiotic features ofPoecilocera picta (Orthoptera,Acrididae)

Cytological study of three distinctly separated populations ofPoecilocera picta revealed a chromosome number of 2N = 18 + XO/ XX. Except for the hemizygosity of a procentric heterochromatic block in the M₆ pair of the Bangalore population, the basic karyotype of the three populations is markedly similar. The autosomal karyotype formula is 2Lt + 4Mt + 1 Mst + 2S st and the telocentric X chromosome is the longest of the complement. All bivalents at pachytene carried procentric heterochromatic blocks. The M₄ is the nucleolus organiser with the NOR region situated interstitially but proximal to the centromere. About 11 μm (4%) of the total (290 μm) autosomal pachytene complement is heterochromatic; a major portion of it is contributed by the S₉ pair which is mostly heterochromatic. Chiasmata are localized proximally and distally and in the S₉ pair their formation is confined to the short procentric euchromatic segment of the long arm. Female meiosis did not reveal any chromomere pattern at pachytene and, unlike in the male, the sex bivalent in the female is indistinguishable from the autosomal bivalents. G- and C-banding patterns in males showed procentric bands in all the chromosomes. In addition there are eight telomeric and two interstitial bands which are C negative. The S₉ pair showed only two bands. The G-banding pattern of the sex chromosome in meiosis showed only a centric band while the heterochromatic body of the facultatively heterochromatic X remained G negative.     

Chromosome banding and genome compartmentalization in fishes

The diploid chromosome number of the Chinese raccoon dog varies from 54 (no B chromosomes) to 58 (4 B chromosomes). The B chromosomes are totally heterochromatic. An electron microscopic study was made of the synaptonemal complexes (SC) in spermatocytes of these animals. The SC karyotype consists of 27 regular chromosome pairs (autosomes and the sex chromosomes) plus the B chromosomes. The Bs pair effectively with one another at pachytene, but the SC axes of the B chromosomes are much denser than those of the A chromosomes. Depending on the number of Bs, both bivalents and multivalents have been observed. When three B chromosomes are present in a cell, parallel alignment of all three SCs can be seen. Formation of multivalents indicates high homology among these supernumerary heterochromatic chromosomes. Fusiform bulges are found along unpaired regions of all chromosomes which are particularly pronounced in diplotene.