Orientation-dependent photonic bandgaps in gold-dust weevil scales and their titania bioreplicates.

The scales of the gold-dust weevil are green because of three-dimensional diamond-type chitin-air photonic crystals with an average periodicity of about 430 nm and a chitin fill fraction of about 0.44. A single scale usually contains one to three crystallites with different lattice orientations.

Elucidating nanostructural organization and photonic properties of butterfly wing scales using hyperspectral microscopy.

Biophotonic nanostructures in butterfly wing scales remain fascinating examples of biological functional materials, with intriguing open questions with regard to formation and evolutionary function. One particularly interesting butterfly species, (Lycaenidae: Theclinae), develops wing scales that contain three-dimensional photonic crystals that closely resemble a single gyroid geometry. Unlike most other gyroid-forming butterflies, develops discrete gyroid crystallites with a pronounced size gradient hinting at a developmental sequence frozen in time.

Opponent processing in the retinal mosaic of nymphalid butterflies.

The eyes of nymphalid butterflies, investigated with incident illumination, show colourful facet reflection patterns-the eye shine-which is uniform or heterogeneous, dependent on the species. Facet colours suggest that the ommatidia contain different sets of photoreceptors and screening pigments, but how the colours and the cell characteristics are associated has not been clearly established. Here, we analyse the retinae of two nymphalids, , which has a uniform eyeshine, and a species with a heterogeneous eye shine, using single-cell recordings, spectroscopy and optical pupillometry.

Simple and complex, sexually dimorphic retinal mosaic of fritillary butterflies.

Butterflies have variable sets of spectral photoreceptors that underlie colour vision. The photoreceptor organization may be optimized for the detection of body coloration. Fritillaries (Argynnini) are nymphalid butterflies exhibiting varying degrees of sexual dimorphism in wing coloration.

Red-green opponency in the long visual fibre photoreceptors of brushfoot butterflies (Nymphalidae).

In many butterflies, the ancestral trichromatic insect colour vision, based on UV-, blue- and green-sensitive photoreceptors, is extended with red-sensitive cells. Physiological evidence for red receptors has been missing in nymphalid butterflies, although some species can discriminate red hues well. In eight species from genera and , we found a novel class of green-sensitive photoreceptors that have hyperpolarizing responses to stimulation with red light.

Neural mechanism of spatio-chromatic opponency in the Drosophila amacrine neurons.

Visual animals detect spatial variations of light intensity and wavelength composition. Opponent coding is a common strategy for reducing information redundancy. Neurons equipped with both spatial and spectral opponency have been identified in vertebrates but not yet in insects.

The red admiral butterfly's living light sensors and signals.

We studied the wing colouration and the compound eyes of red admiral butterflies with optical methods. We measured reflectance spectra of the wing and scales of Vanessa atalanta and modelled the thin film reflectance of the wing membrane and blue scales. We utilized the eyeshine in the compound eye of Vanessa indica to determine the spectral and polarisation characteristics of its optical sensor units, the ommatidia.

Diffusive structural colour in .

Nature's nanostructures can bring about vivid and iridescent colours seen in many insects, notably in beetles and butterflies. While the intense structural colours can be advantageous for display purposes, they may also be appealing to predators and therefore constitute an evolutionary disadvantage. Animals often employ absorption and scattering in order to reduce the directionality of the reflected light and thereby enhance their camouflage.

Horsefly object-directed polarotaxis is mediated by a stochastically distributed ommatidial subtype in the ventral retina.

The ventral compound eye of many insects contains polarization-sensitive photoreceptors, but little is known about how they are integrated into visual functions. In female horseflies, polarized reflections from animal fur are a key stimulus for host detection. To understand how polarization vision is mediated by the ventral compound eye, we investigated the band-eyed brown horsefly using anatomical, physiological, and behavioral approaches.

Compound eyes of the small white butterfly Pieris rapae have three distinct classes of red photoreceptors.

The two subspecies of the small white butterfly, the European Pieris rapae rapae and the Asian P. r. crucivora, differ in wing colouration.

The giant butterfly-moth Paysandisia archon has spectrally rich apposition eyes with unique light-dependent photoreceptor dynamics.

The palm borer moth Paysandisia archon (Burmeister, 1880) (fam. Castniidae) is a large, diurnally active palm pest. Its compound eyes consist of ~ 20,000 ommatidia and have apposition optics with interommatidial angles below 1°.

Classical lepidopteran wing scale colouration in the giant butterfly-moth .

The palm borer moth (Castniidae; giant butterfly-moths) has brown dorsal forewings and strikingly orange-coloured dorsal hindwings with white spots surrounded by black margins. Here, we have studied the structure and pigments of the wing scales in the various coloured wing areas, applying light and electron microscopy and (micro)spectrophotometry, and we analysed the spatial reflection properties with imaging scatterometry. The scales in the white spots are unpigmented, those in the black and brown wing areas contain various amounts of melanin, and the orange wing scales contain a blue-absorbing ommochrome pigment.

Red-shift of spectral sensitivity due to screening pigment migration in the eyes of a moth, .

Background: We have found that the spectral sensitivity of the compound eye in the summer fruit tortrix moth () differs in laboratory strains originating from different regions of Japan. We have investigated the mechanisms underlying this anomalous spectral sensitivity.

Methods: We applied electrophysiology, light and electron microscopy, opsin gene cloning, mathematical modeling, and behavioral analysis.

A fast multispectral light synthesiser based on LEDs and a diffraction grating.

Optical experiments often require fast-switching light sources with adjustable bandwidths and intensities. We constructed a wavelength combiner based on a reflective planar diffraction grating and light emitting diodes with emission peaks from 350 to 630 nm that were positioned at the angles corresponding to the first diffraction order of the reversed beam. The combined output beam was launched into a fibre.

Four photoreceptor classes in the open rhabdom eye of the red palm weevil, Rynchophorus ferrugineus Olivier.

The red palm weevil (RPW) is a severe palm pest with high dispersal capability. Its visual sense allows it to navigate long distances and to discriminate among differently colored traps. We investigated the RPW compound eyes with anatomical and electrophysiological methods.

A cute and highly contrast-sensitive superposition eye - the diurnal owlfly Libelloides macaronius.

The owlfly Libelloides macaronius (Insecta: Neuroptera) has large bipartite eyes of the superposition type. The spatial resolution and sensitivity of the photoreceptor array in the dorsofrontal eye part was studied with optical and electrophysiological methods. Using structured illumination microscopy, the interommatidial angle in the central part of the dorsofrontal eye was determined to be Δϕ=1.

Spatial reflection patterns of iridescent wings of male pierid butterflies: curved scales reflect at a wider angle than flat scales.

The males of many pierid butterflies have iridescent wings, which presumably function in intraspecific communication. The iridescence is due to nanostructured ridges of the cover scales. We have studied the iridescence in the males of a few members of Coliadinae, Gonepteryx aspasia, G.

Spectral reflectance properties of iridescent pierid butterfly wings.

The wings of most pierid butterflies exhibit a main, pigmentary colouration: white, yellow or orange. The males of many species have in restricted areas of the wing upper sides a distinct structural colouration, which is created by stacks of lamellae in the ridges of the wing scales, resulting in iridescence. The amplitude of the reflectance is proportional to the number of lamellae in the ridge stacks.

An expanded set of photoreceptors in the Eastern Pale Clouded Yellow butterfly, Colias erate.

We studied the spectral and polarisation sensitivities of photoreceptors of the butterfly Colias erate by using intracellular electrophysiological recordings and stimulation with light pulses. We developed a method of response waveform comparison (RWC) for evaluating the effective intensity of the light pulses. We identified one UV, four violet-blue, two green and two red photoreceptor classes.

Photoreceptor responses of fruitflies with normal and reduced arrestin content studied by simultaneous measurements of visual pigment fluorescence and ERG.

We have simultaneously measured the electroretinogram (ERG) and the metarhodopsin content via fluorescence in white-eyed, wild-type Drosophila and the arrestin2 hypomorphic mutant (w(-);arr2 (3)) at a range of stimulus wavelengths and intensities. Photoreceptor response amplitude and termination (transition between full repolarization and prolonged depolarizing afterpotential, PDA) were related to visual pigment conversions and arrestin concentration. The data were implemented in a kinetic model of the rhodopsin-arrestin cycle, allowing us to estimate the active metarhodopsin concentration as a function of effective light intensity and arrestin concentration.

Rhabdom constriction enhances filtering by the red screening pigment in the eye of the Eastern Pale Clouded yellow butterfly, Colias erate (Pieridae).

Here we report the remarkable anatomy of the eye of the Eastern Pale Clouded yellow butterfly, Colias erate. An ommatidium of C. erate bears nine photoreceptors, R1-9, which together form a tiered and fused rhabdom.

Probing the mechanism of exocytosis at the hair cell ribbon synapse.

Hearing relies on faithful synaptic transmission at the ribbon synapse of cochlear inner hair cells (IHCs). Postsynaptic recordings from this synapse in prehearing animals had delivered strong indications for synchronized release of several vesicles. The underlying mechanism, however, remains unclear.