Structure of ovaries of scale insects: ii. margarodidae (INSECTA,hemiptera, COCCINEA)

The paired, spindle-shaped ovaries of the second instar of the Polish cochineal, Porphyrophora polonica (L.) (Hemiptera: Coccinea) are filled with cystocytes that are arranged into rosettes. In the centre of each rosette, there is a polyfusome. During the third instar, cystocytes differentiate into oocytes and trophocytes (nurse cells) and ovarioles are formed. Ovaries of adult females are composed of about 300 ovarioles of the telotrophic type. Each of them is subdivided into a tropharium (trophic chamber) and vitellarium. The tropharium consists of trophocytes and arrested oocytes that may develop. The number of germ cells in the trophic chambers varies from 11 to 18 even between the ovarioles of the same ovary. The obtained results seem to confirm the concept of a monophyletic origin of the primitive scale insects (Archaeococcoidea).     

Structure of ovaries in ensign scale insects,the most primitive representatives of Coccomorpha (Insecta,Hemiptera)

The ovaries of Orthezia urticae and Newsteadia floccosa are paired and composed of numerous short ovarioles. Each ovariole consists of an anterior trophic chamber and a posterior vitellarium that contains one developing oocyte. The trophic chamber contains large nurse cells (trophocytes) and arrested oocytes. The total number of germ cells per ovariole (i.e., cluster) is variable, but it is always higher than 32 and less than 64. This suggests that five successive mitotic cycles of a cystoblast plus additional divisions of individual cells are responsible for the generation of the cluster. Cells of the trophic chamber maintain contact with the oocyte via a relatively broad nutritive cord. The trophic chamber and oocyte are surrounded by somatic cells that constitute the inner epithelial sheath around the former and the follicular epithelium around the latter. Anagenesis of hemipteran ovarioles is discussed in relation to the findings presented. © 1995 Wiley-Liss, Inc.     

The ovaries of scale insects (Hemiptera, Coccinea). Morphology and phylogenetic conclusions

Coccoids (Coccinea, Coccoidea, Coccomorpha, scale insects, scales) are a highly diverse group of ectoparasitic insects. They comprise 2 subgroups: primitive archaeococcoids (= Orthezioidea sensu Koteja) and advanced neococcoids (= Coccoidea sensu Koteja). The ovaries of coccoids consist of numerous short telotrophic-meroistic ovarioles. The ovarioles of all investigated species share common characters (e.g. the same mechanism of ovariole development, lack of terminal filaments, occurrence of single oocytes in the vitellaria) supporting the concept of monophyletic origin of this group. Despite these characteristics, the ovaries of archaeococcoids and neococcoids differ in the number of germ cells (oocytes + trophocytes) constituting a single ovariole. In primitive families (Ortheziidae, Margarodidae), this number is relatively large (15-58), whereas in advanced ones (Pseudococcidae, Kermesidae, Eriococcidae, Cryptococcidae, Coccidae, Diaspididae) it is small and usually does not exceed 8. The comparative analysis of the ovary structure in the representatives of Coccinea and closely related Aphidinea (aphids) has revealed that: (1) the organization of archaeococcoid ovaries is more similar to those of aphids than to neococcoids and (2) during the evolution of Coccinea a gradual reduction in the number of germ cells in ovarioles took place.     

Structure and development of the telotrophic ovariole in ensign scale insects (Hemiptera, Coccomorpha: Ortheziidae)

The paired ovaries of young larva of the 3rd instar of Orthezia urticae are filled with numerous germ cell clusters that can be regarded as ovariole anlagen. Germ cells (cystocytes) belonging to one cluster form a rosette, in the centre of which a polyfusome occurs. Staining with rhodamine-phalloidin has revealed that polyfusomes contain numerous microfilaments. The number of cystocytes per cluster is not stable and varies considerably. The ovaries of older larva become elongated with numerous young ovarioles protruding into the body cavity. The ovarioles are not subdivided into the tropharium and vitellarium. In this stage germ cells differentiate into oocytes and trophocytes (nurse cells). The ovaries of adult females are composed of about 20 (Newsteadia floccosa) or 30 (O. urticae) ovarioles. Their trophic chambers contain trophocytes and arrested oocytes. In the vitellarium, at the given moment, only one oocyte develops. It has been observed that after maturation of the first egg the arrested oocytes may develop.     

Cytoarchitecture of the ovarioles in scale insects (Hemiptera,Coccinea)

Telotrophic ovarioles of scale insects are subdivided into tropharia (=trophic chambers) and vitellaria that contain single developing oocytes. Tropharium encloses trophocytes (=nurse cells) and arrested oocytes. The central area of the tropharium, termed the trophic core, is devoid of cells. Both trophocytes and oocytes are connected to the trophic core: trophocytes by cytoplasmic processes, oocytes by means of nutritive cords. The trophic core, processes and nutritive cords are filled with bundles of microtubules. The trophocytes contain large lobated nuclei with giant nucleoli. Fluorescent labelling with DAPI has shown that trophocyte nuclei are characterized by high contents of DNA. In the cortical cytoplasm of trophocytes, numerous microfilaments are present. The developing oocyte is surrounded by a simple follicular epithelium. The cortical cytoplasm of follicular cells contains numerous microtubules and microfilaments.     

Formation and structure of egg capsules in scale insects (Hemiptera, Coccinea) I. Ortheziidae

The paired ovaries of the investigated species are composed of 20-30 ovarioles of a telotrophic-meroistic type. Each ovariole is subdivided into an apical tropharium (=trophic chamber) and a vitellarium that contains a single developing oocyte. This oocyte is surrounded by a mono-layered follicular epithelium that is responsible for synthesis of precursors of egg envelopes. In Orthezia, synthesis and secretion of precursors of egg envelopes (=choriogenesis) and accumulation of reserve substances in the oocyte cytoplasm (=vitellogenesis) start at the same time. The egg capsule is composed of two envelopes: an internal, thick vitelline envelope and an external, very thin chorion. The egg surface is covered with numerous, irregularly arranged waxy filaments of spiral shape. Eggs are devoid of the micropylar, aeropylar and hydropylar openings.     

Chromosome systems in the eriococcidae (Coccoidea Homoptera)

Spermatogenesis is described in two eriococcid species and the observations are compared to those previously reported. In Gossyparia spuria the diploid chromosome number is 28 in both males and females. In the female all the chromosomes are euchromatic. In most male tissues 14 of the chromosomes are euchromatic (E) and 14 are heterochromatic (H). Prior to the first meiotic division in males the number of H chromosomes was reduced. During prophase I all the cells showed 14 E chromosomes and from 1 to over 9 H chromosomes. The range of chromosome numbers in metaphase I was similar to that in prophase I. All the chromosomes divided in anaphase I, and, following differential uncoiling at interkinesis, the E and H groups of chromosomes segregated from each other at anaphase II. Only the E groups formed sperm. The presence of a variable number of H chromosomes and a haploid number of E chromosomes in spermatogenesis suggested the presence of the multiple-D variant of the Comstockiella chromosome system. In this system some of the H chromosomes become euchromatic prior to prophase I of spermatogenesis and pair with their E homologues. All the remaining H chromosomes are thus univalents, while among the E elements, some are univalents and the rest are bivalents. The observed reduction in the number of H chromosomes in the first meiotic division which was previously attributed to pairing among the H chromosomes, is now interpreted to be the result of the return of some of the H chromosomes to a euchromatic state and to their subsequent pairing with their E homologues. Spermatogenesis in Eriococcus araucariae was similar to that of G. spuria except that the reduction in the number of H chromosomes was not as extensive. The chromosome systems of the two species are compared to those of other eriococcids and the differences are briefly discussed.Supported by grant GB1585 from the National Science Foundation, Washington, D. C.     

Independent regulation of microtubule spacing and microtubule stability following redundancy of nutritive tubes in telotrophic ovaries in hemiptera (insecta)

The nutritive tubes that act as conduits between the nutritive cells and the developing oocytes within the ovaries of hemipteran insects, contain vast aggregates of aligned microtubules. During the previtellogenic stages of oogenesis, components synthesised in the nutritive cells pass within the nutritive tubes and accumulate in the oocytes. Using polarised light and electron microscopy, we have monitored the changes in both the spacing and stability of the microtubules which occur when, at the onset of vitellogenesis, translocation within the nutritive tube ceases and the tube becomes redundant. Having investigated nutritive tube redundancy in the ovaries of 4 species of hemipterans, we have discovered the outcome to be similar in each case, with the microtubules losing their characteristic spacing and becoming closely packed prior to their depolymerisation. The feature that differs is the timing of these changes because, in certain species, microtubule depolymerisation closely follows the microtubule rearrangement, while in other species, depolymerisation of the microtubules occurs some considerable time after their change in pattern. This evidence demonstrates that microtubule spacing and stability are regulated independently following redundancy of nutritive tubes, and we speculate upon how this regulation might be achieved within the insect ovaries.     

Ultrastructure of the wax-gland system in subterranean scale insects (homoptera,coccoidea, margarodidae)

The ultrastructure of wax glands (integumentary, stigmatic, and peristigmatic glands) was investigated in larvae, cysts, and adult females and males of species belonging to the genera Porphyrophora, Sphaeraspis, and Eurhizococcus. The general organization and cytological characteristics are similar for all glands studied. Each gland is composed of a single layer of 8 to 40 cells. The glandular cells are characterized by a very large quantity of smooth endoplasmic reticulum which forms dense zones throughout the cytoplasm, but is always placed near the collecting canals in the presence of mitochondria. Each cell has a central canal reservoir which penetrates it deeply and gives rise to a large number of lateral collecting canals, formed by the invagination of the apical plasma membrane. The canals open into a subcuticular cavity forming a common reservoir in which the secretion is accumulated. This reservoir is covered by a modified cuticle formed from the endocuticle and the epicuticle. The endocuticle is composed of a network of fine tubular structures and has many filaments on its surface. The epicuticle is perforated by numerous pores. There is no cuticular duct. The secretion crosses the cuticle in three successive steps. First, it passes through the filaments, then through fine tubular structures of the endocuticle, and finally through the epicuticular pores.     

Gonoid thelytoky in soft scale insects (Coccidae: Homoptera)

Cytological analysis of the thelytokous soft-scale insects Coccus hesperidum L. (2n=14) and Saissetia coffeae (Walker) (2n=16) revealed that while in both species the chromosomes did not pair during prophase I, meiosis consisted of two divisions, the chromosome number was reduced, and diploidy was restored by the fusion of the female pronucleus with the polar nucleus II. The difficulty of trying to classify this type of thelytoky as either automictic or apomictic led to the proposal that a new criterion and new terms be used to classify thelytoky (and parthenogenesis). The new criterion is whether the number of chromosome elements present in the first (or only) metaphase of oogenesis is the same as that present in the oogonia (gonoid thelytoky) or different from it (agonoid thelytoky). The new criterion is superior to the existing criteria because it is unambiguous, and because it groups together forms with a similar tendency towards heterozygosity (or homozygosity). The possible evolution of the forms analyzed as well as the two other thelytokous forms of each species described by Thomsen (1927) are discussed. Another soft-scale insect, Physokermes hemicryphus Dalam, consisted of a diploid (2n=18) and a triploid (3n=27) form, in both of which the chromosomes also did not pair. Each of the three species contained a strain in which only a single nucleolus was present per cell. In C. hesperidum some strains with two nucleoli differed in the size of the nucleoli.     

A survey of scale insects in soil samples from Europe (Hemiptera,Coccomorpha)

In the last decades, several expeditions were organized in Europe by the researchers of the Hungarian Natural History Museum to collect snails, aquatic insects and soil animals (mites, springtails, nematodes, and earthworms). In this study, scale insect (Hemiptera: Coccomorpha) specimens extracted from Hungarian Natural History Museum soil samples (2970 samples in total), all of which were collected using soil and litter sampling devices, and extracted by Berlese funnel, were examined. From these samples, 43 scale insect species (Acanthococcidae 4, Coccidae 2, Micrococcidae 1, Ortheziidae 7, Pseudococcidae 21, Putoidae 1 and Rhizoecidae 7) were found in 16 European countries. In addition, a new species belonging to the family Pseudococcidae, Brevennia larvalis Kaydan, sp. n. and a new species of Ortheziidae, Ortheziola editae Szita & Konczné Benedicty, sp. n. are described and illustrated based on the adult female stage. Revised keys to the adult females of Brevennia and Ortheziola are presented.     

Parasitoeds (Hym.: Aphelinidae) of three scale insects (Hom.: Diaspididae) in a citrus grove in valencia,spain

The parasitoids ofAonidiella aurantii (Maskell),Lepidosaphes beckii (Newman) andParlatoria pergandii Comstock were studied in a Navel orange grove in Valencia, Spain during three years. Four species ofAphytis were identified on yellow sticky traps,Aphytis chrysomphali (Mercet),Aphytis melinus Debach,Aphytis lepidosaphes Compere andAphytis hispanicus (Mercet). No consistent annual pattern was observed in the flight of adults.A. melinus, introduced some years earlier in the grove, was found in very low numbers and showed no signs of increasing and displacingA. chrysomphali as a parasitoid ofA. aurantii. On female scales of the three species sampled at regular intervals from leaves, twigs and fruit, the mean annual rate of active parasitism was similar and ranged from 3.5% to 8%.P. pergandii males were not parasitized, inL. beckii parasitism was usually much lower in male than in female scales, and inA. aurantii it was higher in the males. Scales of the three species were less parasitized on twigs than on leaves, and so wereL. beckii on fruit. The annual trend of parasitism byAphytis on scales fluctuated without a definite pattern. Parasitism byEncarsia inquirenda (Silvestri), an endoparasitoid ofP. pergandii, was more stable throughout the year and increased steadily from year to year.     

Aschersonia basicystis on scale insects (Homoptera: Coccidae) in Venezuela

The fungus Aschersonia basicystison scale insects (Homoptera: Coccidae) is described and illustrated on the basis of the examination of Venezuelan collections, using transmitted light and differential interference contrast optical microscopy.     

中生代线蛉科化石(昆虫纲,脉翅目)

线蛉科是脉翅目中的一个灭绝科,仅发现于中国中侏罗统和蒙古晚侏罗统地层中。线蛉科昆虫脉序独特,为其分类地位的确定以及整个脉翅目翅脉演化的研究提供了重要的线索;此外,线蛉科昆虫前后翅上均具有条带状的斑纹,初步推测这种斑纹在其生存繁衍过程中发挥了积极作用,也可能是导致其灭绝的最直接因素之一。目前线蛉科已发表3属9种,本文对其进行了简要的回顾,并编制了线蛉科化石种检索表,对当时的古环境特征进行了简单推测,初步探讨了翅斑在其生存和灭绝中的作用。     

虻科成虫雌性尾器亚生殖板的研究

应用亚生殖板细微结构的鉴别方法,研究了虻科20种雌性成虫雌性尾器的亚生殖板。结果表明:虻科雌性成虫不同种其尾器亚生殖板整体大小,颜色,有无骨化现象、骨化部位及骨化程度,端缘、基缘凹陷深浅及宽窄,侧突位置、大小,基角大小及形状,毛和鬃的有无、着生位置及多少,皱褶的有无及位置等特征均有变化。虻科成虫雌性尾器亚生殖板的细微结构有种间鉴别的特异性。     

Origin of the different strengths of the (i,i+4) and (i,i+3) leucine pair interactions in helices

Pairs of leucine side chains, spaced either (i,i+3) or (i,i+4), are known to stabilize alanine-based peptide helices, Experiments with new peptide sequences confirm that the (i,i+4) pair interaction is markedly stronger than the (i,i+3) pair interaction. This result is not expected from reported Monte Carlo simulations, which predict that the (i,i+3) interaction is slightly stronger. The interaction strength can be predicted from recently reported measurements of buried non-polar surface area, obtained from structures in the Protein Data Bank: the agreement is reasonable for the (i,i+3) LL interaction but underestimates the (i,i+4) LL interaction. Solvation of peptide groups in the helix backbone may contribute to the different strengths of the two LL pair interactions because different chi(1) leucine rotamers are used and the (i,i+3) pair shields two peptide groups whereas the (i,i+4) pair shields only one. A rough estimate of the backbone solvation effect, based on the difference between the helix propensities of leucine and alanine, agrees with the size of the difference between the (i,i+3) and (i,i+4) leucine pair interactions.     

GOING FURTHER INTO LATE MESOZOIC MESOLYGAEIDS (HETEROPTERA, INSECTA)

A large collection of fossil insects has recently been recovered from the Late Mesozoic nonmarine sediments throughout East Asia, with many specimens regarded as the mesolygaeids, representing a new family Mesolygaeidae of Heteroptera. As Lycoptera Muller and Eosestheria Chen, Mesolygaeus Ping is the common genus of the Jehol fauna Since some of them are geographically widespread and can be easily collected, they are significant to stratigraphic divisions and correlations in East Asia.     

Distribution and abundance of endemic coelostomidiid scale insects (Hemiptera: Coelostomidiidae) in Auckland forests, New Zealand

Sap-feeding insects can excrete considerable quantities of sugar-rich honeydew. In New Zealand, South Island beech (Nothofagus spp.) forests are shaped by the extensive honeydew resource produced by two endemic coelostomidiid species (Ultracoelostoma assimile and U.?brittini) and geckos on northern islands are known to feed on the honeydew of a third endemic coelostomidiid, Coelostomidia zealandica. There are six other endemic coelostomidiid species in New Zealand that utilise a range of plant hosts but the ecological role of these species is poorly understood. A survey of mainland forests in the Auckland Ecological Region was conducted in February?April 2006 to investigate the distribution and abundance of coelostomidiids in this area. Three coelostomidiid species were detected in the survey (C.?zealandica, C.?pilosa and C.?wairoensis) and five new host?scale insect associations were identified. C.?zealandica was uncommon, C.?pilosa was widespread in broadleaved?podocarp forest but only formed light infestations, and C.?wairoensis was present in all teatree stands examined, often forming heavy infestations on k?nuka (Kunzea ericoides). Infested k?nuka trees had sooty moulds growing on them and exotic wasps were regularly seen feeding on C.?wairoensis honeydew. The extent and intensity of C. wairoensis infestation on k?nuka suggests it will have community-level impacts.     

"古翅类"系统发育关系研究进展(昆虫纲,有翅类)

古翅类的系统发育问题是六足总纲中有争议的热点问题之一。对现存古翅类(孵蝣目 蜻蜒目)与新翅类之间的系统发育关系有3种主要观点：古翅类(＝蜉蝣目 蜻蜒目) 新翅类,蜉蝣目 (蜻蜒目 新翅类),蜻蜒目 (蜉蝣目 新翅类)。第1种观点得到化石、形态和部分基因证据支持,第2种观点得到较多形态特征支持,支持第3种观点的证据较少。这一问题的解决有赖于更多昆虫种类、化石以及分子证据的发现和研究。     

A molecular phylogenetic study of armoured scale insects (Hemiptera: Diaspididae)

Abstract.  Armoured scale insects are economically important parasites of woody plants and grasses. They are promising subjects for the evolutionary study of physiology (no complete gut), genetics (chimerism, paternal genome elimination, frequent parthenogenesis) and coevolution (with host plants, parasitoids, Septobasidium fungi, endosymbiotic bacteria). Little phylogenetic work has been accomplished with armoured scales, and uncertainty surrounds their classification. Here, we report the phylogenetic results of Bayesian and parsimony analyses of 705 base pairs of Elongation Factor 1α and 660 base pairs of 28S from eighty-nine species of armoured scale insects, representing forty-seven genera and five tribes in the subfamilies Diaspidinae and Aspidiotinae, together with two outgroups. 28S was aligned based on a secondary structural model. Our results broadly corroborate the major features of the existing classification, although we do not find perfect monophyly of any of the traditionally recognized subfamilies or tribes. The subfamily Aspidiotinae is paraphyletic with respect to the subfamily Diaspidinae. Diaspidinae consists of two main clades that only roughly correspond to the tribes Lepidosaphidini and Diaspidini. Diaspidini is nearly monophyletic, except that it includes a single aspidiotine species. Other members of the tribe Aspidiotini form a clade, except that the clade includes a single species of Leucaspidini and excludes Maskellia and Pseudaonidia . Our results weakly support the hypothesis that the most recent common ancestor of the Diaspididae had adult females that were permanently enclosed within the derm of the second instar (the pupillarial habit) and had diploid adult males that eliminated their paternal genomes during spermatogenesis (late paternal genome elimination).