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Why don’t horseflies land on zebras?
Abstract: Stripes deter horseflies (tabanids) from landing on zebras and, while several mechanisms have been proposed, these hypotheses have yet to be tested satisfactorily. Here, we investigated three possible visual mechanisms that could impede successful tabanid landings (aliasing, contrast and polarization) but additionally explored pattern element size employing video footage of horseflies around differently patterned coats placed on domestic horses. We found that horseflies are averse to landing on highly but not on lightly contrasting stripes printed on horse coats. We could find no evidence for horseflies being attracted to coats that better reflected polarized light. Horseflies were somewhat less attracted to regular than to irregular check patterns, but this effect was not large enough to support the hypothesis of disrupting optic flow through aliasing. More likely it is due to attraction towards larger dark patches present in the irregular check patterns, an idea bolstered by comparing landings to the size of dark patterns present on the different coats. Our working hypothesis for the principal anti-parasite features of zebra pelage are that their stripes are sharply outlined and thin because these features specifically eliminate the occurrence of large monochrome dark patches that are highly attractive to horseflies at close distances.
© 2023. Published by The Company of Biologists Ltd.
Publication Date: 2023-02-17 PubMed ID: 36700395PubMed Central: PMC10088525DOI: 10.1242/jeb.244778Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
This research seeks to understand why horseflies are deterred from landing on zebras. The study explores various visual mechanisms involving aliasing, contrast, polarization, and pattern element size. It finds that horseflies prefer not to land on highly contrasting zebra-like stripes and are somewhat less attracted to regular check patterns. It posits that the principal anti-parasite feature of zebra stripes is their sharply defined and thin parameters, which eliminate the occurrence of large dark patches attractive to horseflies.
Exploring Visual Mechanisms
- The researchers studied three potential visual deterrents for horseflies landing on zebras. These included aliasing, where the distinct bars of the zebra’s pattern might confuse or overwhelm the horsefly’s vision; contrast, where the stark black-and-white pattern of the zebra may seem unattractive or disorienting to horseflies; and polarization, where the manner in which the zebra’s coat reflects light might be off-putting to horseflies.
- The researchers also explored pattern element size as a deterrent by recording how horseflies interacted with differently patterned coats placed on domestic horses.
Results and Findings
- The study found that horseflies were hesitant to land on areas with high contrast, such as the stark black-and-white patterns similar to those found on a zebra.
- There was no evidence that horseflies were attracted or repelled by coats that reflected polarized light.
- Horseflies showed a slight aversion to landing on regular check patterns, but this effect was not big enough to support the aliasing hypothesis about the disruption of optic flow.
- It is suggested that this preference may be due to the attraction towards larger dark patches, which were present in irregular check patterns.
- The pattern size seemed to have an impact on horseflies’ attraction; they preferred landing spots with larger dark patches compared to smaller ones.
Conclusion and Hypothesis
- The researchers concluded that the key feature of zebra stripes that deters horseflies is the sharp, narrow boundaries of the stripes.
- This design eliminates large, single-color dark patches, which the study found to be highly attractive to horseflies.
- Hence, the thin and sharply defined stripes of zebras serve as an effective deterrent against horsefly landings.
Cite This Article
APA
Caro T, Fogg E, Stephens-Collins T, Santon M, How MJ.
(2023).
Why don’t horseflies land on zebras?
J Exp Biol, 226(4), jeb244778.
https://doi.org/10.1242/jeb.244778 Publication
Researcher Affiliations
- School of Biological Sciences, 24 Tyndall Avenue, University of Bristol, Bristol BS8 1TQ, UK.
- School of Biological Sciences, 24 Tyndall Avenue, University of Bristol, Bristol BS8 1TQ, UK.
- School of Biological Sciences, 24 Tyndall Avenue, University of Bristol, Bristol BS8 1TQ, UK.
- School of Biological Sciences, 24 Tyndall Avenue, University of Bristol, Bristol BS8 1TQ, UK.
- School of Biological Sciences, 24 Tyndall Avenue, University of Bristol, Bristol BS8 1TQ, UK.
MeSH Terms
- Horses
- Animals
- Equidae / parasitology
- Diptera
Conflict of Interest Statement
Competing interests The authors declare no competing or financial interests.
References
This article includes 27 references
- Blaho M, Egri A, Bahidszki L, Kriska G, Hegedus R, Akesson S, Horvath G. Spottier targets are less attractive to tabanid flies: on the tabanid-repellency of spotty fur patterns.. PLoS One 2012;7(8):e41138.
- Brady J, Shereni W. Landing responses of the tsetse fly Glossina morsitans morsitans Westwood and the stable fly Stomoxys calcitrans (L.) (Diptera: Glossinidae & Muscidae) to black-and-white patterns: a laboratory study. Bull. Entomol. Res. 78, 301-311.
- Britten KH, Thatcher TD, Caro T. Zebras and Biting Flies: Quantitative Analysis of Reflected Light from Zebra Coats in Their Natural Habitat.. PLoS One 2016;11(5):e0154504.
- Bürkner P-C. Advanced Bayesian multilevel modeling with the R package. R Journal 10, 395-411.
- Caro T. Zebra Stripes. Chicago: University of Chicago Press.
- Caro T. Zebra stripes.. Curr Biol 2020 Sep 7;30(17):R973-R974.
- Caro T, Izzo A, Reiner RC Jr, Walker H, Stankowich T. The function of zebra stripes.. Nat Commun 2014 Apr 1;5:3535.
- Caro T, Argueta Y, Briolat ES, Bruggink J, Kasprowsky M, Lake J, Mitchell MJ, Richardson S, How M. Benefits of zebra stripes: Behaviour of tabanid flies around zebras and horses.. PLoS One 2019;14(2):e0210831.
- Caro T, Huang Y, Arkwright M, How MJ. Biting flies and zebra stripes. Sensory Ecology of Disease Vectors pp. 563-603.
- Colvin J, Gibson G. Host-seeking behavior and management of tsetse.. Annu Rev Entomol 1992;37:21-40.
- Egri A, Blahó M, Kriska G, Farkas R, Gyurkovszky M, Akesson S, Horváth G. Polarotactic tabanids find striped patterns with brightness and/or polarization modulation least attractive: an advantage of zebra stripes.. J Exp Biol 2012 Mar 1;215(Pt 5):736-45.
- Egri Á, Blahó M, Sándor A, Kriska G, Gyurkovszky M, Farkas R, Horváth G. New kind of polarotaxis governed by degree of polarization: attraction of tabanid flies to differently polarizing host animals and water surfaces.. Naturwissenschaften 2012 May;99(5):407-16.
- Gibson G. Do tsetse flies see zebras? A field study of the visual response of tsetse to striped targets. Physiol. Entomol. 17, 141-147.
- Hirsch J, Curcio CA. The spatial resolution capacity of human foveal retina.. Vision Res 1989;29(9):1095-101.
- Horváth G. Polarized Light and Polarization Vision in Animal Sciences. Berlin: Springer.
- Horváth G, Szörényi T, Pereszlényi Á, Gerics B, Hegedüs R, Barta A, Åkesson S. Why do horseflies need polarization vision for host detection? Polarization helps tabanid flies to select sunlit dark host animals from the dark patches of the visual environment.. R Soc Open Sci 2017 Nov;4(11):170735.
- Horváth G, Pereszlényi Á, Száz D, Barta A, Jánosi IM, Gerics B, Åkesson S. Experimental evidence that stripes do not cool zebras.. Sci Rep 2018 Jun 19;8(1):9351.
- Horváth G, Pereszlényi Á, Åkesson S, Kriska G. Striped bodypainting protects against horseflies.. R Soc Open Sci 2019 Jan;6(1):181325.
- How MJ, Zanker JM. Motion camouflage induced by zebra stripes.. Zoology (Jena) 2014 Jun;117(3):163-70.
- How MJ, Gonzales D, Irwin A, Caro T. Zebra stripes, tabanid biting flies and the aperture effect.. Proc Biol Sci 2020 Aug 26;287(1933):20201521.
- Kelley LA, Kelley JL. Animal visual illusion and confusion: the importance of a perceptual perspective. Behav. Ecol. 25, 450-463.
- Kojima T, Oishi K, Matsubara Y, Uchiyama Y, Fukushima Y, Aoki N, Sato S, Masuda T, Ueda J, Hirooka H, Kino K. Cows painted with zebra-like striping can avoid biting fly attack.. PLoS One 2019;14(10):e0223447.
- Korner-Nievergelt F, Roth T, Felten SV, Guélat J, Almasi B, Korner-Nievergelt P. Bayesian Data Analysis in Ecology Using Linear Models with R, BUGS, and Stan. Elsevier.
- Melin AD, Kline DW, Hiramatsu C, Caro T. Zebra Stripes through the Eyes of Their Predators, Zebras, and Humans.. PLoS One 2016;11(1):e0145679.
- Sasaki H, Watanabe M, Tawatsin A, Hashiba T. Tabanus iyoensis (Diptera: Tabanidae) avoid white and pattern like zebra stripe traps in comparison with black one on the field studies. Med. Entomol. Zool. 71, 333-336.
- Tibbs AB, Daly IM, Bull DR, Roberts NW. Noise creates polarization artefacts.. Bioinspir Biomim 2017 Dec 28;13(1):015005.
- Waage JK. How the zebra got its stripes: biting flies as selective agents in the evolution of zebra coloration. J. Entomol. Soc. Southern Africa 44, 351-358.
Citations
This article has been cited 1 times.- Ireland HM, Ruxton GD. Zebra stripes: the questions raised by the answers. Biol Rev Camb Philos Soc 2025 Dec;100(6):2660-2680.
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