Wavelength-specific negatively phototactic responses of the burrowing mayfly larvae Ephoron virgo.

Mayflies are typically negatively phototactic during larval development, whereas the adults possess positive phototaxis. However, no extensive research has been done into the wavelength dependence of phototaxis in any mayfly larvae. We measured the repellency rate of Ephoron virgo larvae to light as a function of wavelength in the 368-743 nm spectral range.

Spectral sensitivity transition in the compound eyes of a twilight-swarming mayfly and its visual ecological implications.

Aquatic insect species that leave the water after larval development, such as mayflies, have to deal with extremely different visual environments in their different life stages. Measuring the spectral sensitivity of the compound eyes of the virgin mayfly () resulted in differences between the sensitivity of adults and larvae. Larvae were primarily green-, while adults were mostly UV-sensitive.

Polarization neutral point pairs of the solar corona and the lunar disc observed during the total solar eclipse on 11 August 1999 in Hungary.

During the total solar eclipses on 11 August 1999 in Kecel (Hungary) and on 29 March 2006 in Side (Turkey), two Hungarian groups performed full-sky imaging polarimetric measurements of the eclipsed sky. They observed the spatiotemporal change of the celestial polarization pattern and detected three polarization neutral points as well as two points with maximal polarization of the sky. Parallel to these studies, the polarization pattern in front of the lunar disc, the solar corona, and the surrounding sky have also been measured.

Bioreplicated coatings for photovoltaic solar panels nearly eliminate light pollution that harms polarotactic insects.

Many insect species rely on the polarization properties of object-reflected light for vital tasks like water or host detection. Unfortunately, typical glass-encapsulated photovoltaic modules, which are expected to cover increasingly large surfaces in the coming years, inadvertently attract various species of water-seeking aquatic insects by the horizontally polarized light they reflect. Such polarized light pollution can be extremely harmful to the entomofauna if polarotactic aquatic insects are trapped by this attractive light signal and perish before reproduction, or if they lay their eggs in unsuitable locations.

Horsefly reactions to black surfaces: attractiveness to male and female tabanids versus surface tilt angle and temperature.

Tabanid flies (Diptera: Tabanidae) are attracted to shiny black targets, prefer warmer hosts against colder ones and generally attack them in sunshine. Horizontally polarised light reflected from surfaces means water for water-seeking male and female tabanids. A shiny black target above the ground, reflecting light with high degrees and various directions of linear polarisation is recognised as a host animal by female tabanids seeking for blood.

How does the water springtail optically locate suitable habitats? Spectral sensitivity of phototaxis and polarotaxis in .

Optical detection of horizontally polarized light is widespread among aquatic insects. This process usually occurs in the UV or blue spectral ranges. Recently, it was demonstrated that at least one collembolan species, the water springtail () also possesses positive polarotaxis to horizontally polarized light.

Striped bodypainting protects against horseflies.

Bodypainting is widespread in African, Australian and Papua New Guinean indigenous communities. Many bodypaintings use white or bright yellow/grey/beige stripes on brown skin. Where the majority of people using bodypainting presently live, blood-sucking horseflies are abundant, and they frequently attack the naked brown regions of the human body surface with the risk of transmitting the pathogens of dangerous diseases.

Method to reduce motion artifacts of sequential imaging polarimetry: long enough exposures minimize polarization blurs of wavy water surfaces.

Researchers studying the polarization characteristics of the optical environment prefer to use sequential imaging polarimetry, because it is inexpensive and simple. This technique takes polarization pictures through polarizers in succession. Its main drawback is, however, that during sequential exposure of the polarization pictures, the target must not move, otherwise so-called motion artifacts are caused after evaluation of the polarization pictures.

Method to improve the survival of night-swarming mayflies near bridges in areas of distracting light pollution.

Numerous negative ecological effects of urban lighting have been identified during the last decades. In spite of the development of lighting technologies, the detrimental effect of this form of light pollution has not declined. Several insect species are affected including the night-swarming mayfly : when encountering bridges during their mass swarming, these mayflies often fall victim to artificial lighting.

Polarization sensitivity in Collembola: an experimental study of polarotaxis in the water-surface-inhabiting springtail Podura aquatica.

The ventral eye of the water-surface-inhabiting springtail Podura aquatica has six ommatidia with horizontal and vertical microvilli and perceives light from the ventral, frontal and frontodorsal regions, whereas the dorsal eye possesses two upward-looking ommatidia with vertical microvilli. The ventral eye may detect water by its polarization sensitivity, even if the insect is resting with its head slightly tipped down on a raised surface. The polarization sensitivity and polarotaxis in springtails (Collembola) have not been investigated.

Mayflies are least attracted to vertical polarization: A polarotactic reaction helping to avoid unsuitable habitats.

Like other aquatic insects, mayflies are positively polarotactic and locate water surfaces by means of the horizontal polarization of water-reflected light. However, may vertically polarized light also have implications for the swarming behaviour of mayflies? To answer this question, we studied in four field experiments the behavioural responses of Ephoron virgo and Caenis robusta mayflies to lamps emitting horizontally and vertically polarized and unpolarized light. In both species, unpolarized light induces positive phototaxis, horizontally polarized light elicits positive photo- and polarotaxis, horizontally polarized light is much more attractive than unpolarized light, and vertically polarized light is the least attractive if the stimulus intensities and spectra are the same.

Lamp-lit bridges as dual light-traps for the night-swarming mayfly, Ephoron virgo: interaction of polarized and unpolarized light pollution.

Ecological photopollution created by artificial night lighting can alter animal behavior and lead to population declines and biodiversity loss. Polarized light pollution is a second type of photopollution that triggers water-seeking insects to ovisposit on smooth and dark man-made objects, because they simulate the polarization signatures of natural water bodies. We document a case study of the interaction of these two forms of photopollution by conducting observations and experiments near a lamp-lit bridge over the river Danube that attracts mass swarms of the mayfly Ephoron virgo away from the river to oviposit on the asphalt road of the bridge.

Seasonality and daily activity of male and female tabanid flies monitored in a Hungarian hill-country pasture by new polarization traps and traditional canopy traps.

Blood-sucking female tabanid flies cause serious problems for animals and humans. For the control of tabanids, the knowledge about their seasonality and daily activity is of great importance. Earlier, only traditional traps capturing exclusively female tabanids have been used to survey tabanid activity.

Unexpected attraction of polarotactic water-leaving insects to matt black car surfaces: mattness of paintwork cannot eliminate the polarized light pollution of black cars.

The horizontally polarizing surface parts of shiny black cars (the reflection-polarization characteristics of which are similar to those of water surfaces) attract water-leaving polarotactic insects. Thus, shiny black cars are typical sources of polarized light pollution endangering water-leaving insects. A new fashion fad is to make car-bodies matt black or grey.

Phototaxis and polarotaxis hand in hand: night dispersal flight of aquatic insects distracted synergistically by light intensity and reflection polarization.

Based on an earlier observation in the field, we hypothesized that light intensity and horizontally polarized reflected light may strongly influence the flight behaviour of night-active aquatic insects. We assumed that phototaxis and polarotaxis together have a more harmful effect on the dispersal flight of these insects than they would have separately. We tested this hypothesis in a multiple-choice field experiment using horizontal test surfaces laid on the ground.

Orientation with a Viking sun-compass, a shadow-stick, and two calcite sunstones under various weather conditions.

It is widely accepted that Vikings used sun-compasses to derive true directions from the cast shadow of a gnomon. It has been hypothesized that when a cast shadow was not formed, Viking navigators relied on crude skylight polarimetry with the aid of dichroic or birefringent crystals, called "sunstones." We demonstrate here that a simple tool, that we call "shadow-stick," could have allowed orientation by a sun-compass with satisfying accuracy when shadows were not formed, but the sun position could have reliably been estimated.

Stripes disrupt odour attractiveness to biting horseflies: battle between ammonia, CO₂, and colour pattern for dominance in the sensory systems of host-seeking tabanids.

As with mosquitoes, female tabanid flies search for mammalian hosts by visual and olfactory cues, because they require a blood meal before being able to produce and lay eggs. Polarotactic tabanid flies find striped or spotted patterns with intensity and/or polarisation modulation visually less attractive than homogeneous white, brown or black targets. Thus, this reduced optical attractiveness to tabanids can be one of the functions of striped or spotty coat patterns in ungulates.

A new tabanid trap applying a modified concept of the old flypaper: linearly polarising sticky black surfaces as an effective tool to catch polarotactic horseflies.

Trapping flies with sticky paper sheets is an ancient method. The classic flypaper has four typical characteristics: (i) its sticky paper is bright (chamois, light yellow or white), (ii) it is strip-shaped, (iii) it hangs vertically, and (iv) it is positioned high (several metres) above ground level. Such flypapers, however, do not trap horseflies (tabanids).

Cavemen were better at depicting quadruped walking than modern artists: erroneous walking illustrations in the fine arts from prehistory to today.

The experts of animal locomotion well know the characteristics of quadruped walking since the pioneering work of Eadweard Muybridge in the 1880s. Most of the quadrupeds advance their legs in the same lateral sequence when walking, and only the timing of their supporting feet differ more or less. How did this scientific knowledge influence the correctness of quadruped walking depictions in the fine arts? Did the proportion of erroneous quadruped walking illustrations relative to their total number (i.

Spottier targets are less attractive to tabanid flies: on the tabanid-repellency of spotty fur patterns.

During blood-sucking, female members of the family Tabanidae transmit pathogens of serious diseases and annoy their host animals so strongly that they cannot graze, thus the health of the hosts is drastically reduced. Consequently, a tabanid-resistant coat with appropriate brightness, colour and pattern is advantageous for the host. Spotty coats are widespread among mammals, especially in cattle (Bos primigenius).

New kind of polarotaxis governed by degree of polarization: attraction of tabanid flies to differently polarizing host animals and water surfaces.

Aquatic insects find their habitat from a remote distance by means of horizontal polarization of light reflected from the water surface. This kind of positive polarotaxis is governed by the horizontal direction of polarization (E-vector). Tabanid flies also detect water by this kind of polarotaxis.

How can horseflies be captured by solar panels? A new concept of tabanid traps using light polarization and electricity produced by photovoltaics.

Horseflies (Diptera: Tabanidae) can cause severe problems for humans and livestock because of the continuous annoyance performed and the diseases vectored by the haematophagous females. Therefore, effective horsefly traps are in large demand, especially for stock-breeders. To catch horseflies, several kinds of traps have been developed, many of them attracting these insects visually with the aid of a black ball.

Polarotactic tabanids find striped patterns with brightness and/or polarization modulation least attractive: an advantage of zebra stripes.

The characteristic striped appearance of zebras has provoked much speculation about its function and why the pattern has evolved, but experimental evidence is scarce. Here, we demonstrate that a zebra-striped horse model attracts far fewer horseflies (tabanids) than either homogeneous black, brown, grey or white equivalents. Such biting flies are prevalent across Africa and have considerable fitness impact on potential mammalian hosts.

No evidence for behavioral responses to circularly polarized light in four scarab beetle species with circularly polarizing exocuticle.

The strongest known circular polarization of biotic origin is the left-circularly polarized (LCP) light reflected from the metallic shiny exocuticle of certain beetles of the family Scarabaeidae. This phenomenon has been discovered by Michelson in 1911. Although since 1955 it has been known that the human eye perceives a visual illusion when stimulated by circularly polarized (CP) light, it was discovered only recently that a stomatopod shrimp is able to perceive circular polarization.

Polarotaxis in non-biting midges: female chironomids are attracted to horizontally polarized light.

Non-biting midges (Chironomidae, Diptera) are widely distributed aquatic insects. The short-living chironomid adults swarm in large numbers above water surfaces, and are sometimes considered a nuisance. They are vectors of certain bacteria, and have a key-role in benthic ecosystems.