A new argument against cooling by convective air eddies formed above sunlit zebra stripes

Pereszlényi, Ádám; Száz, Dénes; Jánosi, Imre M.; Horváth, Gábor

doi:10.1038/s41598-021-95105-4

Cited by 5 publications

References 18 publications

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Ecological advantage of polarized light pollution: positive effect of a dark lake patch at a canal inflow on habitat of non-biting midges

Egri,

Pereszlényi,

Szekeres

et al. 2023

Limnology

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Dark artificial surfaces reflecting highly and horizontally polarized light usually have negative effects on polarotactic aquatic insects detecting their habitats by the horizontal polarization of water-reflected light. This ecologically disadvantageous phenomenon is called polarized light pollution. We have observed that the water between the concrete walls of a harbour of the Hungarian Lake Balaton is continuously dark from autumn to spring due to the inflow of a canal rich in dissolved humic substances. Using ground-born imaging polarimetry, we demonstrated that this dark water patch reflects light with higher degrees of polarization than the brighter lake water. Our hypothesis was that the stronger horizontally polarized light reflected from the dark water patch is more attractive to swarming, water-seeking and egg-laying non-biting midges (Chironomidae) than the surrounding brighter lake water. With larval samplings, we showed that both the density and the average size of chironomid larvae were significantly larger in the harbour than in the surrounding lake. This finding may represent an ecological advantage of polarized light pollution: polarotactic chironomids are intensely attracted to a strongly and horizontally polarizing, seasonally dark water patch at the canal inflow, where the abundance of larvae increases. It should be taken into consideration that increased larval abundance might result in increased swarming intensity which could affect humans by causing considerable nuisance.

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Ecological advantage of polarized light pollution: positive effect of a dark lake patch at a canal inflow on habitat of non-biting midges

Egri,

Pereszlényi,

Szekeres

et al. 2023

Limnology

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Blood-seeking horseflies prefer vessel-imitating temperature gradients on host-mimicking targets: Experimental corroboration of a new explanation of the visual unattractiveness of zebras to tabanids

Száz

Takacs

Egri

et al. 2023

International Journal for Parasitology

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Sunlit zebra stripes may confuse the thermal perception of blood vessels causing the visual unattractiveness of zebras to horseflies

Takacs

Száz

Vincze

et al. 2022

Sci Rep

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Multiple hypotheses have been proposed for possible functions of zebra stripes. The most thoroughly experimentally supported advantage of zebra stripes is their visual unattractiveness to horseflies (tabanids) and tsetse flies. We propose here a plausible hypothesis why biting horseflies avoid host animals with striped pelages: in sunshine the temperature gradients of the skin above the slightly warmer blood vessels are difficult to distinguish from the temperature gradients induced by the hairs at the borderlines of warmer black and cooler white stripes. To test this hypothesis, we performed a field experiment with tabanids walking on a host-imitating grey test target with vessel-mimicking thin black stripes which were slightly warmer than their grey surroundings in sunshine, while under shady conditions both areas had practically the same temperature as demonstrated by thermography. We found that horseflies spend more time walking on thin black stripes than surrounding grey areas as expected by chance, but only when the substrate is sunlit. This is because the black stripes are warmer than the surrounding grey areas in the sun, but not in the shade. This is consistent with the flies’ well-documented attraction to warmer temperatures and provides indirect support for the proposed hypothesis. The frequent false vessel locations at the numerous black–white borderlines, the subsequent painful bitings with unsuccessful blood-sucking attempts and the host’s fly-repellent reactions enhance considerably the chance that horseflies cannot evade host responses and are swatted by them. To eliminate this risk, a good evolutionary strategy was the avoidance of striped (and spotted) host animals.

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A new argument against cooling by convective air eddies formed above sunlit zebra stripes

Cited by 5 publications

References 18 publications

Ecological advantage of polarized light pollution: positive effect of a dark lake patch at a canal inflow on habitat of non-biting midges

Ecological advantage of polarized light pollution: positive effect of a dark lake patch at a canal inflow on habitat of non-biting midges

Blood-seeking horseflies prefer vessel-imitating temperature gradients on host-mimicking targets: Experimental corroboration of a new explanation of the visual unattractiveness of zebras to tabanids

Sunlit zebra stripes may confuse the thermal perception of blood vessels causing the visual unattractiveness of zebras to horseflies

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