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.     

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.     

Morpho蝴蝶结构显色特性研究

M orpho蝴蝶结构显色是结构显色研究中最热门的分支之一,其显色原理主要在于物理光学作用。根据M orpho蝴蝶的表皮微结构,建立了计算模型;利用时域有限差分方法(fin ite d ifference tim e dom a in m ethodFDTD)对结构模型在自然光照射下的结构显色特性进行计算,根据计算结果分析了M orpho蝴蝶的颜色之谜,揭示了其结构显色的原理。计算分析结果与观察结果完全吻合,说明研究方法具有可行性。     

Wavelength-selective and anisotropic light-diffusing scale on the wing of the Morpho butterfly

We have found that cover scales on the wing of the butterfly Morpho didius possess specially designed microscopic structures for wavelength-selective reflection and contribute considerably to the brilliant blue colour of the wing. In addition, the cover scale functions as an anisotropic optical diffuser which diffuses light only in one plane, while it makes the range of reflection narrower in the orthogonal plane. The quantitative analyses for the wavelength-selection mechanism and the peculiar optical diffuser are given and the role of such a special optical effect is discussed from physical and biological viewpoints.     

The predominance of polyunsaturated fatty acids in the butterfly Morpho peleides before and after metamorphosis

We hypothesized that the polyunsaturated fatty acids of the butterfly were probably derived from the diet and that there might be a great loss of body fat during metamorphosis. To substantiate these hypotheses, we analyzed the fatty acid composition and content of the diet, the larva, and the butterfly Morpho peleides. Both the diet and the tissues of the larva and butterfly had a high concentration of polyunsaturated fatty acids. In the diet, linolenic acid accounted for 19% and linoleic acid for 8% of total fatty acids. In the larva, almost 60% of the total fatty acids were polyunsaturated: linolenic acid predominated at 42% of total fatty acids, and linoleic acid was at 17%. In the butterfly, linolenic acid represented 36% and linoleic acid represented 11% of total fatty acids. The larva had a much higher total fatty acid content than the butterfly (20.2 vs. 6.9 mg). Our data indicate that the transformation from larva to butterfly during metamorphosis drastically decreased the total fatty acid content. There was bioenhancement of polyunsaturated fatty acids from the diet to the larva and butterfly. This polyunsaturation of membranes may have functional importance in providing membrane fluidity useful in flight.     

人为干扰对壶瓶山国家级自然保护区蝴蝶物种多样性的影响

为了解人为干扰对壶瓶山国家级自然保护区(以下简称壶瓶山保护区)蝴蝶物种多样性的影响, 调查组于2017-2018年间采用样线法抽取5条样线对壶瓶山保护区的蝴蝶群落进行调查研究, 分析了人为干扰对蝴蝶发生规律的影响, 并比较了壶瓶山保护区中不同程度人为干扰情况下的蝴蝶发生差异。本调查共观测到蝴蝶6,711只, 隶属5科19亚科119属190种, 各样线的优势种主要有宽边黄粉蝶(Eurema hecabe)、东方菜粉蝶(Pieris canidia)、酢浆灰蝶(Pseudozizeeria maha)、宽带凤蝶(Papilio nephelus)等。轻度干扰情况下物种多样性最高, 其次为无干扰条件, 而中度干扰情况下蝴蝶物种多样性最低, 即小规模的耕作-居住环境有利于蝴蝶的聚集, 而增加现有的人为干扰程度或扩大干扰范围, 可致使群落中蝴蝶物种数减少、优势类群数量增加。     

Multifractal Characterization of Butterfly Wings Scales

A lot of insect families have physical structures created by evolution for coloration. These structures are a source of ideas for new bio-inspired materials. The aim of this study was to quantitatively characterize the micromorphology of butterfly wings scales using atomic force microscopy and multifractal analysis. Two types of butterflies, Euploea mulciber (“striped blue crow”) and Morpho didius (“giant blue morpho”), were studied. The three-dimensional (3D) surface texture of the butterfly wings scales was investigated focusing on two areas: where the perceived colors strongly depend on and where they do not depend on the viewing angle. The results highlight a correlation between the surface coloration and 3D surface microtexture of butterfly wings scales.     

The conceptual and practical implications of interpreting diet breadth mechanistically in generalist predatory insects

Seasonal polyphenism in animal colour patterns indicates that temporal variation in selection pressures maintains phenotypic plasticity. Spring generation of the polyphenic European map butterfly Araschnia levana has an orange–black fritillary‐like pattern whilst individuals of the summer generation are black with white bands across the wings. What selects for the colour difference is unknown. Because predation is a major selection pressure for insect coloration, we first tested whether map butterfly coloration could have a warning function (i.e. whether the butterflies are unpalatable to birds). In a following field experiment with butterfly dummies we tested whether the spring form is better protected than the summer form from predators in the spring, and vice versa in the summer. The butterflies were palatable to birds (blue tits Cyanistes caeruleus) and in the field the spring and summer form dummies were attacked equally irrespective of season. Therefore, we found no evidence that the map butterfly is warning‐coloured or that seasonal polyphenism is an adaptation to avian predation. Because insect coloration has multiple functions and map butterfly coloration is linked to morphology, life history and development it is likely that the interplay of several selection pressures explains the evolution of colour polyphenism. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??.     

A model for colour pattern formation in the butterfly wing of Papilio dardanus

The butterfly Papilio dardanus is well known for the spectacular phenotypic polymorphism in the female of the species. We show that numerical simulations of a reaction diffusion model on a geometrically accurate wing domain produce spatial patterns that are consistent with many of those observed on the butterfly. Our results suggest that the wing coloration is due to a simple underlying stripe-like pattern of some pigment-inducing morphogen. We focus on the effect of key factors such as parameter values for mode selection, threshold values which determine colour, wing shape and boundary conditions. The generality of our approach should allow us to investigate other butterfly species. The relationship between these key factors and gene activities is discussed in the context of recent biological advances.     

Hearing in the crepuscular owl butterfly (Caligo eurilochus,Nymphalidae)

Tympanal organs are widespread in Nymphalidae butterflies, with a great deal of variability in the morphology of these ears. How this variation reflects differences in hearing physiology is not currently understood. This study provides the first examination of hearing organs in the crepuscular owl butterfly, Caligo eurilochus. We examined the tuning and sensitivity of the C. eurilochus hearing organ, called Vogel’s organ, using laser Doppler vibrometry and extracellular neurophysiology. We show that the C. eurilochus ear responds to sound and is most sensitive to frequencies between 1 and 4 kHz, as confirmed by both the vibration of the tympanal membrane and the physiological response of the associated nerve branches. In comparison to the hearing of its diurnally active relative, Morpho peleides, C. eurilochus has a narrower frequency range with higher auditory thresholds. Hypotheses explaining the function of hearing in this crepuscular butterfly are discussed.     

宁夏贺兰山自然保护区蝴蝶群落多样性及其环境影响因子

宁夏贺兰山自然保护区蝴蝶群落多样性及其与环境因素的关系,2017年5-9月采用样线法对贺兰山东麓6类生境和不同干扰类型10条样线的蝴蝶群落结构及其多样性季节动态进行调查。共记录蝴蝶5科36属45种,蛱蝶科Nymphalidae的属和物种数最多,为17属19种;凤蝶科Papilionidae最少,仅1属1种。菜粉蝶Pieris rapae、云粉蝶Pontia daplidice、斑缘豆粉蝶Colias erate和小檗绢粉蝶Aporia hippia是该地区的优势种,个体数量分别占总个体数的11.76%、11.63%、11.21%和10.17%。不同生境样线优势类群和常见类群不同。蝴蝶的栖息地偏好与寄主植物有关,蝴蝶的生境分布类型可分为生境广布型、湿润平原型、荒漠半荒漠草原型和山地森林型。蝴蝶群落Shannon-Wiener多样性和丰富度指数以灰榆疏林草地生境最高,优势度最低。各物种在生境内的季节变化趋势与不同生境植被生长季节相关,高峰期为7-8月。不同调查时间蝴蝶的优势种和常见种不同。物种数以7月份调查最多,有33种,占全年调查总物种数的73.33%;5月份调查最少,有20种。蝴蝶群落Shannon-Wiener多样性和丰富度指数以8月份最大,5月份最小。蝴蝶成虫发生类型分为全年发生型、春季型、夏季型和夏秋季型。不同生境和季节发生的优势种可以作为对生境状况进行评估的指示类群。采用CCA分析物种分布与微环境因子的关系,海拔对蝴蝶物种多样性分布格局有显著影响。蝴蝶丰富度与海拔、温度、风速显著正相关。适度干扰有利于蝶类多样性增加,较强的人为干扰会影响蝶类栖息环境,降低蝶类多样性。因此,生境差异性和干扰与蝴蝶群落的物种多样性密切相关,维持贺兰山垂直植被带的生境异质性和保持适度干扰是保护蝴蝶多样性的关键。     

Effects of diet and metamorphosis upon the sterol composition of the butterfly Morpho peleides

Whole body sterol metabolism in insects has seldom been studied. We were able to design an appropriate study at a butterfly farm in Belize. We collected six larvas of butterfly (Morpho peleides), their food (leaves of Pterocarpus bayessii), and their excretions. In addition, six adult butterflies were collected. The sterols of the diet, the larva, and adult butterfly were analyzed by gas-liquid chromatography. The structures of these sterols were identified by digitonin precipitation, GC-MS, and NMR. Four sterols (cholesterol, campesterol, stigmasterol, and sitosterol) and a sterol mixture were found in the food, the body, and the excreta of the larva. The tissue sterol content of the larva was 326 microg. They consumed 276 microg of sterols per day. Their excretion was 185 microg per day as sterols. The total tissue sterol contents of the larva and butterfly were similar, but they had different sterol compositions, which indicated interconversion of sterols during development. There was a progressive increase in the cholesterol content from larva to butterfly and a decrease in the content of sitosterol and other plant sterols, which were likely converted to cholesterol. Our data indicated an active sterol metabolism in butterfly larva. Diet played an important role in determining its sterol composition. During metamorphosis, there was an interconversion of sterols. This is the first paper documenting the fecal sterol excretion in insects as related to dietary intakes.     

Flower colour adaptation in a mimetic orchid

Although the tremendous variability in floral colour among angiosperms is often attributed to divergent selection by pollinators, it is usually difficult to preclude the possibility that floral colour shifts were driven by non-pollinator processes. Here, we examine the adaptive significance of flower colour in Disa ferruginea, a non-rewarding orchid that is thought to attract its butterfly pollinator by mimicking the flowers of sympatric nectar-producing species. Disa ferruginea has red flowers in the western part of its range and orange flowers in the eastern part--a colour shift that we hypothesized to be the outcome of selection for resemblance to different local nectar-producing plants. Using reciprocal translocations of red and orange phenotypes as well as arrays of artificial flowers, we found that the butterfly Aeropetes tulbaghia, the only pollinator of the orchid, preferred both the red phenotype and red artificial flowers in the west where its main nectar plant also has red flowers, and both the orange phenotype and orange artificial flowers in the east, where its main nectar plant has orange flowers. This phenotype by environment interaction demonstrates that the flower colour shift in D. ferruginea is adaptive and driven by local colour preference in its pollinator.     

Convergent evolution of neuroendocrine control of phenotypic plasticity in pupal colour in butterflies

Phenotypic plasticity in pupal colour occurs in three families of butterflies (the Nymphalidae, Papilionidae and Pieridae), typically in species whose pupation sites vary unpredictably in colour. In all species studied to date, larvae ready for pupation respond to environmental cues associated with the colour of their pupation sites and moult into cryptic light (yellow–green) or dark (brown–black) pupae. In nymphalids and pierids, pupal colour is controlled by a neuroendocrine factor, pupal melanization-reducing factor (PMRF), the release of which inhibits the melanization of the pupal cuticle resulting in light pupae. In contrast, the neuroendocrine factor controlling pupal colour in papilionid butterflies results in the production of brown pupae. PMRF was extracted from the ventral nerve chains of the peacock butterfly Inachis io (Nymphalidae) and black swallowtail butterfly Papilio polyxenes (Papilionidae). When injected into pre-pupae, the extracts resulted in yellow pupae in I. io but brown pupae in P. polyxenes. These results suggest that the same neuroendocrine factor controls the plasticity in pupal colour, but that plasticity in pupal colour in these species has evolved independently (convergently).     

Phylogeny and diversification of the cloud forest Morpho sulkowskyi group (Lepidoptera,Nymphalidae) in the evolving Andes

The monophyletic Morpho sulkowskyi butterfly group, endemic of Andean cloud forests, was studied to test the respective contributions of Mio‐Pliocene intense uplift period and Pleistocene glacial cycles on Andean biodiversity. We sampled nine taxa covering the whole geographical range of the group. Two mitochondrial and two nuclear genes were analysed using a Bayesian method. We established a dated phylogeny of the group using a relaxed clock method and a wide‐outgroup approach. To discriminate between two hypotheses, we used a biogeographical probabilistic method. Results suggest that the ancestor of the M. sulkowskyi group originated during the Middle–Late Miocene uplift of the Eastern Cordillera in northern Peru. Biogeographical inference suggests that the M. sulkowskyi and Morpho lympharis clades diverged in the northern Peruvian Andes. The subsequent divergences, from the Late Miocene to the Late Pliocene, should have resulted from a dispersal towards the Northern Andes (M. sulkowskyi clade), after the closure of the West Andean Portal separating the Central and Northern Andes, and a southwards dispersal along the Peruvian and Bolivian Eastern Cordilleras (M. lympharis clade). Only a few divergences occurred at the very end of the Pliocene or during the Pleistocene, a period when the more recent uplifts interfered with Pleistocene glacial cycles.     

Population biology of tropical African butterflies. Sex ratio and genetic variation in Acraea encedon

In Uganda the butterfly, Acraea encedon (L.), occurs in well-defined populations that are largely genetically and ecologically isolated from each other. During the course of a large-scale capture-recapture programme about 18,000 different individuals were marked and released, and from these and many recaptures aspects of the population structure were investigated. Some populations are composed of almost all females while in other populations the sex ratio is normal. In the predominantly female populations many females remain unmated and produce infertile eggs, laying them on plants that are not foodplants and on each other. In such populations there is intense aggregating behaviour. Males live longer than females and each male may mate with several different females. There is evidence for the existence of a self-regulating mechanism in the predominantly female populations in which population size and male frequency are reciprocally dependent. Acraea encedon exists in a large variety of sympatric colour forms, the frequency of which varies from population to population. Some colour forms survive better than others. The hindwing of Acraea encedon has 20 black spots each of which can be absent in any particular butterfly. The relative frequency of missing spots varies from population to population. The ecological genetics of Acraea encedon is discussed in relation to theories of mimicry and polymorphism.     

Butterfly wings: Colour patterns and now gene expression patterns

The particular fascination of butterfly wings for developmental biologists (and others) lies in their spectacular array of colour patterns. The evolutionary and developmental relationships between these patterns have been analysed and we know something of the cell interactions involved in their formation⁽¹⁾. Now butterfly homologues of Drosophila wing-patterning genes have been identified, and their expression patterns offer the first clues to the molecular mechanisms which specify wing colour patterns⁽²⁾.     

Efficiency of Fruit Juice Feeding in Morpho peleides (Nymphalidae, Lepidoptera)

We have described the feeding behavior of the frugivorous butterfly Morpho peleides (Butler 1872) under various conditions and tested its ability to take up fluid from selected natural and artificial food sources in comparison with the nectarvorous Vanessa cardui (Linnaeus 1758). Both nymphalids showed similar probing behavior except for one particular proboscis movement and the fact that M. peleides was unable to feed from Lantana flowers. In 2-min feeding trials, M. peleides imbibed a greater amount of fluid from the food sources, with the most conspicuous difference on rotting banana. Without time restriction, M. peleides gained a significantly greater percentage of body weight from soaked plotting paper, whereas nosignificant difference occurred from tubular artificial flowers. The ability of M. peleides to feed more efficiently from wet surfaces than V. cardui is discussed in context with proboscis morphology.     

Pterin pigments amplify iridescent ultraviolet signal in males of the orange sulphur butterfly, Colias eurytheme

Animal colouration is typically the product of nanostructures that reflect or scatter light and pigments that absorb it. The interplay between these colour-producing mechanisms may influence the efficacy and potential information content of colour signals, but this notion has received little empirical attention. Wing scales in the male orange sulphur butterfly (Colias eurytheme) possess ridges with lamellae that produce a brilliant iridescent ultraviolet (UV) reflectance via thin-film interference. Curiously, these same scales contain pterin pigments that strongly absorb wavelengths below 550 nm. Given that male UV reflectance functions as a sexual signal in C. eurytheme, it is paradoxical that pigments in the wing scales are highly UV absorbing. We present spectrophotometric analyses of the wings before and after pterin removal that show that pterins both depress the amplitude of UV iridescence and suppress a diffuse UV reflectance that emanates from the scales. This latter effect enhances the directionality and spectral purity of the iridescence, and increases the signal's chromaticity and potential signal content. Our findings also suggest that pterins amplify the contrast between iridescent UV reflectance and scale background colour as a male's wings move during flight.     

鸡公山自然保护区蝶类多样性及其影响因素

2019年4-10月,在鸡公山自然保护区的核心区和实验区内不同生境、不同人为干扰程度的区域选取6条样线,对蝶类群落进行了观测研究.共记录蝴蝶3431头,隶属于10科79属127种;其中蛱蝶科Nymphalidae的种类数最多,共23属36种;粉蝶科Pieridae和灰蝶科Lycaenidae为保护区优势科,菜粉蝶Pie...