Limited-view iridescence in the butterfly Ancyluris meliboeus.

Few mechanisms exist in nature that effect colour reflectivity, simultaneously high in spectral purity and in intensity, over a strictly limited portion of solid angle above a surface. Fewer still bring about such colour reflectivity with an angle dependence that is distinct from the colour transition associated with conventional multilayer interference. We have discovered that the ventral wings of the butterfly Ancyluris meliboeus exhibit these optical effects, and that they result from remarkable nano-scale architecture on the wing scales of the butterfly. This nano-structure is in the form of high-tilt multilayering that, as a result of abrupt termination of the multilayers, brings about diffraction concurrently with interference. The product is bright structural colour in a limited angular region over the ventral wing surface that enables remarkably strong flicker and colour contrast through minimal wing movement. The visibility effects associated with its colour, in terms of bright and dark zones of the observation hemisphere over the wing surface, are described. We suggest the purpose of the high-contrast ventral wing visibility associated with A. meliboeus is at-rest signalling; this is distinct from the dorsal wing visibility of other species such as those of the genus Morpho, the function of which is largely for in-flight signalling.     

Mechanism of the wing colouration in the dragonfly Zenithoptera lanei (Odonata: Libellulidae) and its role in intraspecific communication

Zenithoptera dragonflies are known for their remarkable bluish colouration on their wings and unique male behaviour of folding and unfolding their wings while perching. However, nothing is known about the optical properties of such colouration and its structural and functional background. In this paper, we aimed to study the relationship between the wing membrane ultrastructure, surface microstructure and colour spectra of male wings in Zenithoptera lanei and test the hypothesis that colouration functions as a signal in territorial fights between males. The results show that the specific wing colouration derives from interference in alternating layers of melanized and unmelanized cuticle in the wing membrane, combined with diffuse scattering in two different layers of wax crystals on the dorsal wing surface, one lower layer of long filaments, and one upper layer of leaf-shaped crystals. The results also show that the thicker wax coverage of the dorsal surface of the wings results in increased brightness and reduced chroma. In the field experiments, we have demonstrated that there is a reduction of aggressive reactions of rivals towards individuals with experimentally reduced amount of blue wing colouration.     

Morphology of hindwing veins in the shield bug Graphosoma italicum (Heteroptera: Pentatomidae)

Light, fluorescence, and electron microscopy were applied to cross sections and -breakage and whole-mount preparations of the anterior hindwing vein of the shield bug Graphosoma italicum. These analyses were complemented by investigations of the basal part of the forewing Corium and Clavus. The integration of structural, histological, and fluorescence data revealed a complex arrangement of both rigid and elastic structures in the wall of wing veins and provided insights into the constitution of transition zones between rigid and elastic regions. Beneath the exocuticular layers, which are continuous with the dorsal and ventral cuticle of the wing membrane, the lumen of the veins is encompassed by a mesocuticular layer, an internal circular exocuticular layer, and an internal longitudinal endocuticular layer. Separate parallel lumina within the anterior longitudinal vein of the hindwing, arranged side-by-side rostro-caudally, suggest that several veins have fused in the phylogenetic context of vein reduction in the pentatomid hindwing. Gradual structural transition zones and resilin enrichment between sclerotized layers of the vein wall and along the edges of the claval furrow are interpreted as mechanical adaptations to enhance the reliability and durability of the mechanically stressed wing veins.     

Evolutionary genetics of dorsal wing colour in Colias butterflies

The evolution of butterfly wing colouration is strongly affected by its multiple functions and by the correlated evolution of wing colour elements. Both factors may prevent local adaptation to ecological conditions. We investigated one aspect of wing colouration, the degree of dorsal wing melanization, in the butterfly Colias philodice eriphyle across an elevational gradient and its correlation with another aspect of wing colouration, ventral wing melanization. Dorsal wing melanization increased with elevation and these differences persisted in a common environment. Full-sibling analysis revealed high heritability for males but only intermediate heritability for females. The correlation between ventral and dorsal melanization showed significant elevational and sex-specific differences. In males the two traits were highly correlated, whereas in females the strength of the correlation decreased with increasing elevation. We conclude that uncoupling of ventral and dorsal melanization has evolved in females but not in males and discuss possible mechanisms underlying uncoupling.     

Colour pattern homology and evolution in Vanessa butterflies (Nymphalidae: Nymphalini): eyespot characters

Ocelli are serially repeated colour patterns on the wings of many butterflies. Eyespots are elaborate ocelli that function in predator avoidance and deterrence as well as in mate choice. A phylogenetic approach was used to study ocelli and eyespot evolution in Vanessa butterflies, a genus exhibiting diverse phenotypes among these serial homologs. Forty‐four morphological characters based on eyespot number, arrangement, shape and the number of elements in each eyespot were defined and scored. Ocelli from eight wing cells on the dorsal and ventral surfaces of the forewing and hindwing were evaluated. The evolution of these characters was traced over a phylogeny of Vanessa based on 7750 DNA base pairs from 10 genes. Our reconstruction predicts that the ancestral Vanessa had 5 serially arranged ocelli on all four wing surfaces. The ancestral state on the dorsal forewing and ventral hindwing was ocelli arranged in two heterogeneous groups. On the dorsal hindwing, the ancestral state was either homogenous or ocelli arranged in two heterogeneous groups. On the ventral forewing, we determined that the ancestral state was organized into three heterogeneous groups. In Vanessa, almost all ocelli are individuated and capable of independent evolution relative to other colour patterns except for the ocelli in cells ?1 and 0 on the dorsal and ventral forewings, which appear to be constrained to evolve in parallel. The genus Vanessa is a good model system for the study of serial homology and the interaction of selective forces with developmental architecture to produce diversity in butterfly colour patterns.     

Respiratory system of the primitive moth Micropterix calthella (Linnaeus) (Lepidoptera : Micropterigidae)

The 1st thoracic spiracular atrium is closed by anterior and posterior muscle fibres extending between its dorsal and ventral wall. The 2nd thoracic spiracle has only a single (anterior) closing lip, movable by a muscle inserting on the wall below the spiracular aperture; this configuration may be a lepidopteran ground-plan autapomorphy. There are functional spiracles on abdominal segments I – VII, each with a closing “bow” and “lever”. There are intrinsic occlusor muscles in all abdominal spiracles and the 1st spiracle has an extrinsic (ventral) dilator. Dorsal dilator muscles or ligaments are absent. A dorsal and a ventral tracheal trunk extend from the 1st thoracic spiracle into the head; the latter supplies the mouthparts and the antenna; there is no connection between the dorsal and ventral cephalic trunk systems. There is a single series of lateral connectives between the spiracles of each side. There is a ventral tracheal commissure in both pterothoracic segments, but none in the prothorax. In each pterothoracic segment an anterior and a posterior tracheal arch give off branches to the wing and anastomose with each other on their downwards course into the leg. Wing tracheation is greatly reduced. The anterior and posterior tracheae of each wing are independent of each other. There is a dorsal commissure in abdominal segment VIII; ventral abdominal commissures are lacking in Micropterix, although present in other micropterigid genera. The terminalia are partly supplied from tracheae arising in segment VII. Air sacs occur in the tibiae only. Phylogenetic aspects of holometabolan tracheation patterns are discussed.     

Homologies in the colour patterns of the genus Charaxes (Lepidoptera: Nymphalidae)

The phylogenetically and morphologically diverse patterns of Charaxes can be reduced to a simple set of pattern elements which can be homologized throughout the genus. At least five types of correspondence (homologies) exist among pattern elements: those between (1) species, (2) forewing and hindwing, (3) dorsal and ventral wing surface, (4) serial wing-cells, and (5) individual pattern elements within a single wing-cell. Differences in Charaxes colour patterns result from the distortion, elaboration, enlargement, reduction or loss of individual pattern elements. Further variation is often the result of dislocation of pattern elements from their serial homologues in neighbouring wing-cells, and fusion of individual pattern elements to create larger areas of colour. The type of analysis presented in this paper should be broadly applicable within the Lepidoptera and may prove useful in studying the systematics of colour patterns and the evolution of the developmental system that gives rise to them.     

Females show greater changes in wing colour with latitude than males in the green‐veined white butterfly,Pieris napi (Lepidoptera: Pieridae)

In butterflies, wing colour may simultaneously be under sexual selection in the context of mating selection and natural selection in the context of thermoregulation. In the present study, we collected mated females of the green‐veined white butterfly (Pieris napi) from locations spanning 960 km of latitude across Fennoscandia, and investigated sex‐specific latitudinal wing colour variation in their offspring raised under identical conditions. We measured wing colour characteristics, including reflectance at wavelengths 300–700 nm and the degree of wing melanization. At all latitudes, females reflected more light in the short wavelengths (< 400 nm) and less in the long wavelengths (> 450 nm), and they were more melanized than males. However, female wing colour varied more with latitude than that of males. Among females, long wavelength reflectance decreased, whereas short wavelength reflectance and melanization increased, towards the north. By contrast, among males, latitudinal variation was found only in the ventral hindwing melanization. These results are consistent with the idea that the balance between natural and sexual selection acting on wing colour changes with latitude differently in males than females. The dark wing colour of females in the north may be a thermoregulatory adaptation, although males may be constrained from evolving the dark dorsal wing colour favoured by natural selection because of constant sexual selection across latitudes. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??.     

The expanding alloscutal cuticle in adults of the argasid tick Argas (Persicargas) robertsi (Acari: Ixodoidea)

The extensible cuticle of Argas (P.) robertsi is tuberculate and deeply folded when the tick is unfed but expands rapidly during feeding. During this expansion the epicuticle becomes less convoluted and the underlying endocuticle stretches but there is no significant alteration in thickness. However, the stretched cuticle has taken on a more open structure. Increase in surface area is restricted to a blister-like expansion because of an inextensible lateral suture which separates the dorsal and ventral surfaces. The cuticle is very hydrophobic, contains 9.9% chitin in the female and 8.9% in the male and the cuticular proteins are largely basic. The cuticle has similar properties to that of the ixodid tick Boophilus microplus but differs from it in fine structure. These differences appear to be related to the time sequence of cuticle synthesis and deposition and to the cycle of expansion and contraction which takes place each time A. (P.) robertsi feeds.     

Anatomy of the extrinsic gut musculature of Gammarus minus (Crustacea: Amphipoda)

Inserting on the buccal and esophageal foregut of Gammarus minus are numerous pairs of serially arranged dorsal dilator muscles, a single pair of lateral muscles, and two pairs of posterior muscles. Muscles of the cardiac stomach include three dorsal sets, a single pair associated with the pterocardiac ossicles, and two pairs inserting on the ventral aspect. A single pair of muscles inserts on the lateral aspect of the pyloric stomach. The extrinsic muscles of the foregut originate from exoskeletal apodemes of the cephalothoracic cuticle, sockets of the mandible, and a maxillary bridge that lies just ventral to the cardiac stomach. The extrinsic musculature of the hindgut is restricted to the rectal region and consists of paired dorsal and ventral series in an X-configuration. A single unpaired muscle inserts on the ventral midline. Extrinsic muscles of the hindgut originate from the integument of the last pleonic segment. The general arrangement of extrinsic gut muscles in G. minus is similar but not identical to that of other amphipods studied. However, the pattern is quite different from that of other malacostracans.     

Structure of the green lacewing tympanal organ (Chrysopa carnea,neuroptera)

Small swellings near the base of the radial vein in each fore wing of the green lacewing, Chrysopa carnea, resemble typical insect tympanal organs, but some important differences are apparent. The swellings are bounded dorsally and laterally by thick cuticle and ventrally by thin, membranous cuticle. The ventral membrane is formed by a single, thin sheet of exocuticle with flattened hypodermis internally, but lacks the tracheal component that forms part of the tympanum in the typical insect tympanal organ. The portion of the membrane beneath each swelling is rippled while proximally it is smooth. In contrast to typical insect tympanal organs, the swellings in C. carnea are largely fluid-filled since an unexpanded trachea runs through each organ. A distal and a proximal chordotonal organ composed of typical chordotonal sensory units are associated with each swelling. The distal organ contains from five to seven units while the proximal organ is composed of from 18 to 20 units. Each sensory unit is composed of three readily identifiable cells. Distally, an attachment cell unites with the membrane and is contiguous with the scolopale cell, which surrounds the dendrite of the bipolar neuron. On the basis of the morphological evidence, one would not expect these swellings to function as sound receptors. However, the results of physiological and behavioral experiments, presented elsewhere, show that these organs are receptors for ultrasound.     

Structural or pigmentary? Origin of the distinctive white stripe on the blue wing of a Morpho butterfly

A few species of Morpho butterflies have a distinctive white stripe pattern on their structurally coloured blue wings. Since the colour pattern of a butterfly wing is formed as a mosaic of differently coloured scales, several questions naturally arise: are the microstructures the same between the blue and white scales? How is the distinctive whiteness produced, structurally or by means of pigmentation? To answer these questions, we have performed structural and optical investigations of the stripe pattern of a butterfly, Morpho cypris. It is found that besides the dorsal and ventral scale layers, the wing substrate also has the corresponding stripe pattern. Quantitative optical measurements and analysis using a simple model for the wing structure reveal the origin of the higher reflectance which makes the white stripe brighter.     

Tissue remodeling during maturation of the Drosophila wing

The final step in morphogenesis of the adult fly is wing maturation, a process not well understood at the cellular level due to the impermeable and refractive nature of cuticle synthesized some 30 h prior to eclosion from the pupal case. Advances in GFP technology now make it possible to visualize cells using fluorescence after cuticle synthesis is complete. We find that, between eclosion and wing expansion, the epithelia within the folded wing begin to delaminate from the cuticle and that delamination is complete when the wing has fully expanded. After expansion, epithelial cells lose contact with each other, adherens junctions are disrupted, and nuclei become pycnotic. The cells then change shape, elongate, and migrate from the wing into the thorax. During wing maturation, the Timp gene product, tissue inhibitor of metalloproteinases, and probably other components of an extracellular matrix are expressed that bond the dorsal and ventral cuticular surfaces of the wing following migration of the cells. These steps are dissected using the batone and Timp genes and ectopic expression of alphaPS integrin, inhibitors of Armadillo/beta-catenin nuclear activity and baculovirus caspase inhibitor p35. We conclude that an epithelial-mesenchymal transition is responsible for epithelial delamination and dissolution.     

Bursicon signaling mutations separate the epithelial-mesenchymal transition from programmed cell death during Drosophila melanogaster wing maturation

Following eclosion from the pupal case, wings of the immature adult fly unfold and expand to present a flat wing blade. During expansion the epithelia, which earlier produced the wing cuticle, delaminate from the cuticle, and the epithelial cells undergo an epithelial–mesenchymal transition (EMT). The resulting fibroblast-like cells then initiate a programmed cell death, produce an extracellular matrix that bonds dorsal and ventral wing cuticles, and exit the wing. Mutants that block wing expansion cause persistence of intact epithelia within the unexpanded wing. However, the normal progression of chromatin condensation and fragmentation accompanying programmed cell death in these cells proceeds with an approximately normal time course. These observations establish that the Bursicon/Rickets signaling pathway is necessary for both wing expansion and initiation of the EMT that leads to removal of the epithelial cells from the wing. They demonstrate that a different signal can be used to activate programmed cell death and show that two distinct genetic programs are in progress in these cells during wing maturation.     

嗅觉和视觉在中华微刺盲蝽对马缨丹定向行为中的作用

对马缨丹(Lantana camara)、黄花马缨丹(Lantana camara cv.‘Flava')和紫花马缨丹(Lantanamontevidensis)花序上中华微刺盲蝽(Campylomma chinensis)的密度调查结果表明,中华微刺盲蝽在3种颜色马缨丹花序上的分布与花序颜色无关(偏相关系数为0.240,P=0.147,n=40),但与花序中的黄胸蓟马数量和花序中小花数的偏相关系数分别为0.512(P＜0.0001,n=0)和0.451(P＜0.0001,n=40),达到极显著水平.中华微刺盲蝽对不同颜色粘卡的试验也表明,该盲蝽寻找植物寄主时,视觉刺激并不起作用.四臂嗅觉仪的试验结果表明,中华微刺盲蝽对马缨丹的气味有强烈的趋向作用.采用固相微萃取和气相-质谱联用技术分析表明,3种马缨丹花序的挥发物有7种相同的化学成分.     

Transformations of epithelial monolayers during wing development of Manduca sexta

The two epithelial monolayers of the insect wing undergo striking morphogenetic changes during the course of adult development, but the exact interactions between these monolayers were not evident until the ultrastructure of the cells was carefully examined. The interaction of the dorsal monolayer with the ventral monolayer continually changes as the two initially separate monolayers first lose their pupal basal laminae and then come together along a sharp interface to form microtubule-associated junctions. As blood space between the two monolayers expands 2 days later, new adult basal laminae and cuticle form. Concomitantly the epithelial cells stretch along their apicobasal axes to create a thin cellular M layer halfway between the dorsal and ventral surfaces of the wing that represents the site where connections between the monolayers are maintained at specialized basal junctions. The elongated processes of each monolayer that make up this M layer first fasciculate and then span the space separating the two monolayers, but only at relatively widely-spaced intervals. During later stages of adult development, dense aggregates of microtubules appear in these epithelial processes and presumably contract as cells dramatically shorten along their apicobasal axes during expansion of the wing. Examination of the ultrastructure of the developing adult wing has revealed how certain cellular events can account for the mechanics of cuticle and wing expansion after adult emergence.     

Location,morphology and histology of sex pheromone glands of the female gypsy moth, Lymantria dispar (L.)

Scanning electron microscopy, histology and a male wing fanning bioassay were used in this study to locate the sex pheromone-producing glands of the female gypsy moth, Lymantria dispar. When exposed to female sex pheromone, adult males exhibit a strong wing fanning behaviour prior to take off. We found that adult males showed positive response to calling females and to tissue extract from both dorsal and ventral portions of the intersegmental membrane between 8th and 9th-abdominal segments. A typical male response usually starts with elevation of antennae, movement of head in different directions, walking, wing fanning and onset of search flight. Histological and scanning electron microscopic studies suggested that the sex pheromone glands are located on the dorsal and ventral aspects of the intersegmental membrane. The glands appear as two highly convoluted integumentary areas with hypertrophied glandular epidermal cells.     

Mariambera,a new genus of Orthocladiinae from Brazil (Insecta: Diptera,Chironomidae)

The genus Mariambera is erected based on the males of M. amazonica n. sp. from Amazonas and M. mariae n. sp. from Minas Gerais. The new genus is easily recognized by the distinctive anal point which has a rounded dorsal lobe with microtrichia and a triangular ventral lobe with very strong, marginal setae, in combination with bare eyes and wing membrane, squama with setae, antenna without strong apical seta, and apparently few, short, very weak, hair-like acrostichals in anterior 1/3 of scutum.     

The cell biology of Drosophila wing metamorphosis in vitro

Summary We have examined the metamorphosis of the wing imaginal disc of Drosophila during culture in vitro in the continuous presence of 20-hydroxy ecdysone (0.1 g/ ml). We find that the sequence of cellular changes in the wing blade during culture closely match those occurring in situ, involving two periods at which the dorsal and ventral surfaces are joined only by cell processes containing trans-alar microtubule arrays. Good pupal and imaginal cuticle secretion is found in this system.     

Structure of the cuticle of the alpine weta,Hemideina maori (Saussure) (Orthoptera: Stenopelmatidae)

Sclerotized cuticle segments from the thorax, dorsal abdomen, and ventral abdomen of the alpine, weta Hemideina maori (Saussure) (Orthoptera: Stenopelmatidae) were examined by light microscopy and by scanning and transmission electron microscopy. An epicuticle, exocuticle (outer and inner), mesocuticle, endocuticle, and deposition layer are present in transverse sections. The epicuticle is further composed of a cuticulin layer and inner epicuticle, the latter being finely laminated and containing narrow wax canals that terminate below the cuticle surface. Openings to dermal gland ducts are visible on the surface as are large setae and smaller sensory pegs. Frozen fractured cuticle reveals the presence of horizontal ducts or channels that run laterally within the cuticle. The structure of weta cuticle is compared with that of the common house cricket and arthropods in general.