Zebra stripes repel horseflies...how can we use this information?
by Louisa Amirault
Biologist Gábor Horváth and his colleagues have come up with a new explaination as to why zebras have their crazy black and white stripes. Afterall, it's not like they use their pattern for camouflage. In the Journal of Experimental Biology, the team published their discovery that zebra stripes are the least attractive hide pattern to tabanids...aka HORSEFLIES!
Horváth and his team conducted their study in a horsefly-infested horse farm near Budapest. First, they tested how attractive these nasty insects found black and white striped patterns by varying the width, density and angle of the stripes and the direction of polarization of the light that they reflected. They found that the patterns attracted fewer flies as the stripes became narrower, with the narrowest stripes attracting the fewest horseflies.
Next, the team then tested the attractiveness of white, dark and striped horse models. They suspected that the striped horse would attract an intermediate number of flies between the white and dark models, because they already knew that horseflies are more attracted to dark colors than white... and the zebra has both. They were surprised to find that the striped model was the least attractive of all.
When the team measured the stripe widths and polarization patterns of light reflected from real zebra hides, they found that the zebra's pattern correlated well with the patterns that were least attractive to horseflies.
"We conclude that zebras have evolved a coat pattern in which the stripes are narrow enough to ensure minimum attractiveness to tabanid flies (horseflies)," says the team and they add, "The selection pressure for striped coat patterns as a response to blood-sucking dipteran parasites is probably high in this region [Africa]."
The fact that zebra embryos start off dark and the white stripes develop before birth is supporting evidence to the idea that these stripes are part of nature's protection plan. The painful bites and annoying nature of the horsefly tends to distract grazing animals from grazing, so it makes sense. Though nature didn't bless the zebra with a hide that blends into the dusty plains or enormous size to stomp large predators, it made them less appealing to the blood suckers. I'd take that gift!
So, how does this study impact the horse industry? Well, equine clothing manufacturers may be designing a zebra patterned fly sheet as you read this. We can deck our horses out in zebra sheets, wraps, halters and halter fuzzies this spring and summer. Maybe put some zebra striping on the water buckets and the barn roof? What, too much? Well, after the plethora of horse flies last summer, I'm willing to try anything including covering my horses with greasy zebra stripes made from Swat ointment.
So, maybe you will try to use this new research to justify your love of animal prints or maybe not. Eitherway, it's interesting research. Maybe we can convince the great minds of biology to conduct a similar experiment on leopard appaloosas.
Data source: The Journal of Experimental Biology. The original article was written by Kathryn Knight. for further info on this study, please visit the above link.