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

Blaho M, Herczeg T, Kriska G, Egri A, Szaz D, Farkas A, Tarjanyi N, Czinke L, Barta A, Horvath G - PLoS ONE (2014)

Bottom Line: Since rough (matt) surfaces depolarize the reflected light, one of the ways of reducing polarized light pollution is to make matt the concerned surface.On the basis of these, our two novel findings are that (a) matt car-paints are highly polarization reflecting, and (b) these matt paints are not suitable to repel polarotactic insects.Thus, changing shiny black car painting to matt one is a disadvantageous fashion fad concerning the reduction of polarized light pollution of black vehicles.

View Article: PubMed Central - PubMed

Affiliation: Environmental Optics Laboratory, Department of Biological Physics, Physical Institute, Eötvös University, Budapest, Hungary.

ABSTRACT
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. Since rough (matt) surfaces depolarize the reflected light, one of the ways of reducing polarized light pollution is to make matt the concerned surface. Consequently, matt black/grey cars may not induce polarized light pollution, which would be an advantageous feature for environmental protection. To test this idea, we performed field experiments with horizontal shiny and matt black car-body surfaces laid on the ground. Using imaging polarimetry, in multiple-choice field experiments we investigated the attractiveness of these test surfaces to various water-leaving polarotactic insects and obtained the following results: (i) The attractiveness of black car-bodies to polarotactic insects depends in complex manner on the surface roughness (shiny, matt) and species (mayflies, dolichopodids, tabanids). (ii) Non-expectedly, the matt dark grey car finish is much more attractive to mayflies (being endangered and protected in many countries) than matt black finish. (iii) The polarized light pollution of shiny black cars usually cannot be reduced with the use of matt painting. On the basis of these, our two novel findings are that (a) matt car-paints are highly polarization reflecting, and (b) these matt paints are not suitable to repel polarotactic insects. Hence, the recent technology used to make matt the car-bodies cannot eliminate or even can enhance the attractiveness of black/grey cars to water-leaving insects. Thus, changing shiny black car painting to matt one is a disadvantageous fashion fad concerning the reduction of polarized light pollution of black vehicles.

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Mayflies attracted en masse to shiny black cars due to the highly and horizontally polarized light reflected from the car-body.(A, B) Mass-swarming Ephemerella hendrickson. (C) Egg-laying Ephemera danica. (D) Thousands of mass-swarming female Ephoron virgo mayflies landed on a windscreen, onto which they laid their yellow egg batches. Photos A and B were taken by Dr. Rebecca Allen (Michigan State University, USA), while photos C and D originate from Dr. György Kriska (Eötvös University, Budapest, Hungary).
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pone-0103339-g001: Mayflies attracted en masse to shiny black cars due to the highly and horizontally polarized light reflected from the car-body.(A, B) Mass-swarming Ephemerella hendrickson. (C) Egg-laying Ephemera danica. (D) Thousands of mass-swarming female Ephoron virgo mayflies landed on a windscreen, onto which they laid their yellow egg batches. Photos A and B were taken by Dr. Rebecca Allen (Michigan State University, USA), while photos C and D originate from Dr. György Kriska (Eötvös University, Budapest, Hungary).

Mentions: Shiny car-bodies attract water-leaving insects [1]–[3], because the hood, roof and boot reflect horizontally polarized light [4], [5], and these insects are lured to this optical signal since they detect water by means of the horizontal polarization of water-reflected light [6]–[19]. This positive polarotaxis induced by the reflection polarization of artificial surfaces is the main reason for polarized light pollution [20]. Thus, shiny black cars are typical sources of polarized light pollution [4], [21], a spectacular consequence of which can be seen in Fig. 1 showing mass-swarming mayflies attracted to shiny black cars. The mayflies in Fig. 1 laid their egg batches (each containing 6000-9000 eggs) onto car-bodies, and these eggs perish quickly due to dehydration. Ephoron virgo (Ephemeroptera: Polymitarcyidae; Fig. 1D) is not only endangered [22], but also a highly protected mayfly species in Europe [23].


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

Blaho M, Herczeg T, Kriska G, Egri A, Szaz D, Farkas A, Tarjanyi N, Czinke L, Barta A, Horvath G - PLoS ONE (2014)

Mayflies attracted en masse to shiny black cars due to the highly and horizontally polarized light reflected from the car-body.(A, B) Mass-swarming Ephemerella hendrickson. (C) Egg-laying Ephemera danica. (D) Thousands of mass-swarming female Ephoron virgo mayflies landed on a windscreen, onto which they laid their yellow egg batches. Photos A and B were taken by Dr. Rebecca Allen (Michigan State University, USA), while photos C and D originate from Dr. György Kriska (Eötvös University, Budapest, Hungary).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4116178&req=5

pone-0103339-g001: Mayflies attracted en masse to shiny black cars due to the highly and horizontally polarized light reflected from the car-body.(A, B) Mass-swarming Ephemerella hendrickson. (C) Egg-laying Ephemera danica. (D) Thousands of mass-swarming female Ephoron virgo mayflies landed on a windscreen, onto which they laid their yellow egg batches. Photos A and B were taken by Dr. Rebecca Allen (Michigan State University, USA), while photos C and D originate from Dr. György Kriska (Eötvös University, Budapest, Hungary).
Mentions: Shiny car-bodies attract water-leaving insects [1]–[3], because the hood, roof and boot reflect horizontally polarized light [4], [5], and these insects are lured to this optical signal since they detect water by means of the horizontal polarization of water-reflected light [6]–[19]. This positive polarotaxis induced by the reflection polarization of artificial surfaces is the main reason for polarized light pollution [20]. Thus, shiny black cars are typical sources of polarized light pollution [4], [21], a spectacular consequence of which can be seen in Fig. 1 showing mass-swarming mayflies attracted to shiny black cars. The mayflies in Fig. 1 laid their egg batches (each containing 6000-9000 eggs) onto car-bodies, and these eggs perish quickly due to dehydration. Ephoron virgo (Ephemeroptera: Polymitarcyidae; Fig. 1D) is not only endangered [22], but also a highly protected mayfly species in Europe [23].

Bottom Line: Since rough (matt) surfaces depolarize the reflected light, one of the ways of reducing polarized light pollution is to make matt the concerned surface.On the basis of these, our two novel findings are that (a) matt car-paints are highly polarization reflecting, and (b) these matt paints are not suitable to repel polarotactic insects.Thus, changing shiny black car painting to matt one is a disadvantageous fashion fad concerning the reduction of polarized light pollution of black vehicles.

View Article: PubMed Central - PubMed

Affiliation: Environmental Optics Laboratory, Department of Biological Physics, Physical Institute, Eötvös University, Budapest, Hungary.

ABSTRACT
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. Since rough (matt) surfaces depolarize the reflected light, one of the ways of reducing polarized light pollution is to make matt the concerned surface. Consequently, matt black/grey cars may not induce polarized light pollution, which would be an advantageous feature for environmental protection. To test this idea, we performed field experiments with horizontal shiny and matt black car-body surfaces laid on the ground. Using imaging polarimetry, in multiple-choice field experiments we investigated the attractiveness of these test surfaces to various water-leaving polarotactic insects and obtained the following results: (i) The attractiveness of black car-bodies to polarotactic insects depends in complex manner on the surface roughness (shiny, matt) and species (mayflies, dolichopodids, tabanids). (ii) Non-expectedly, the matt dark grey car finish is much more attractive to mayflies (being endangered and protected in many countries) than matt black finish. (iii) The polarized light pollution of shiny black cars usually cannot be reduced with the use of matt painting. On the basis of these, our two novel findings are that (a) matt car-paints are highly polarization reflecting, and (b) these matt paints are not suitable to repel polarotactic insects. Hence, the recent technology used to make matt the car-bodies cannot eliminate or even can enhance the attractiveness of black/grey cars to water-leaving insects. Thus, changing shiny black car painting to matt one is a disadvantageous fashion fad concerning the reduction of polarized light pollution of black vehicles.

Show MeSH
Related in: MedlinePlus