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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

Horváth, Gábor; Szörényi, Tamás; Perészlenyi, ; Gerics, Balázs; Hegedüs, Ramón; Barta, András and Åkesson, Susanne LU (2017) In Royal Society Open Science 4(11).
Abstract

Horseflies (Tabanidae) are polarotactic, being attracted to linearly polarized light when searching for water or host animals. Although it is well known that horseflies prefer sunlit dark and strongly polarizing hosts, the reason for this preference is unknown. According to our hypothesis, horseflies use their polarization sensitivity to look for targets with higher degrees of polarization in their optical environment, which as a result facilitates detection of sunlit dark host animals. In this work, we tested this hypothesis. Using imaging polarimetry, we measured the reflection–polarization patterns of a dark host model and a living black cow under various illumination conditions and with different vegetation backgrounds. We focused... (More)

Horseflies (Tabanidae) are polarotactic, being attracted to linearly polarized light when searching for water or host animals. Although it is well known that horseflies prefer sunlit dark and strongly polarizing hosts, the reason for this preference is unknown. According to our hypothesis, horseflies use their polarization sensitivity to look for targets with higher degrees of polarization in their optical environment, which as a result facilitates detection of sunlit dark host animals. In this work, we tested this hypothesis. Using imaging polarimetry, we measured the reflection–polarization patterns of a dark host model and a living black cow under various illumination conditions and with different vegetation backgrounds. We focused on the intensity and degree of polarization of light originating from dark patches of vegetation and the dark model/cow. We compared the chances of successful host selection based on either intensity or degree of polarization of the target and the combination of these two parameters. We show that the use of polarization information considerably increases the effectiveness of visual detection of dark host animals even in front of sunny–shady–patchy vegetation. Differentiation between a weakly polarizing, shady (dark) vegetation region and a sunlit, highly polarizing dark host animal increases the efficiency of host search by horseflies.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Horseflies, Imaging polarimetry, Parasite–host interaction, Polarization vision, Tabanids, Visual ecology
in
Royal Society Open Science
volume
4
issue
11
publisher
Royal Society
external identifiers
  • scopus:85033579383
  • wos:000416787500018
ISSN
2054-5703
DOI
10.1098/rsos.170735
language
English
LU publication?
yes
id
1b9c1dbd-5542-455b-9454-87b86c55406e
date added to LUP
2017-11-20 10:45:11
date last changed
2018-02-20 03:00:14
@article{1b9c1dbd-5542-455b-9454-87b86c55406e,
  abstract     = {<p>Horseflies (Tabanidae) are polarotactic, being attracted to linearly polarized light when searching for water or host animals. Although it is well known that horseflies prefer sunlit dark and strongly polarizing hosts, the reason for this preference is unknown. According to our hypothesis, horseflies use their polarization sensitivity to look for targets with higher degrees of polarization in their optical environment, which as a result facilitates detection of sunlit dark host animals. In this work, we tested this hypothesis. Using imaging polarimetry, we measured the reflection–polarization patterns of a dark host model and a living black cow under various illumination conditions and with different vegetation backgrounds. We focused on the intensity and degree of polarization of light originating from dark patches of vegetation and the dark model/cow. We compared the chances of successful host selection based on either intensity or degree of polarization of the target and the combination of these two parameters. We show that the use of polarization information considerably increases the effectiveness of visual detection of dark host animals even in front of sunny–shady–patchy vegetation. Differentiation between a weakly polarizing, shady (dark) vegetation region and a sunlit, highly polarizing dark host animal increases the efficiency of host search by horseflies.</p>},
  articleno    = {170735},
  author       = {Horváth, Gábor and Szörényi, Tamás and Perészlenyi,  and Gerics, Balázs and Hegedüs, Ramón and Barta, András and Åkesson, Susanne},
  issn         = {2054-5703},
  keyword      = {Horseflies,Imaging polarimetry,Parasite–host interaction,Polarization vision,Tabanids,Visual ecology},
  language     = {eng},
  month        = {11},
  number       = {11},
  publisher    = {Royal Society},
  series       = {Royal Society Open Science},
  title        = {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},
  url          = {http://dx.doi.org/10.1098/rsos.170735},
  volume       = {4},
  year         = {2017},
}