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But how exactly do stripes do this? Now scientists can rule out a theory, according to a new study published Tuesday in the Proceedings of the Royal Society Journal.
The researchers looked into the nature of the disorienting effect of flies and ruled out the hypothesis that a common optical illusion known as the “openness effect” has a role in dazzling them.
“Not only will these exciting studies bring us closer to understanding one of the world’s most iconic and photogenic species, but they will be of great interest to farmers trying to reduce the damage caused by fly bites and even horse clothing businesses in general, ”Tim Caro, co-lead author of the study and professor at the School of Biological Sciences at the University of Bristol, said in a statement.
Dear and his colleague Martin How, a researcher from Bristol, put zebra-print coats on domestic horses for their research, a good alternative to studying zebras in the wild.
Tabanid horseflies could not slow down to land on horses wearing the striped coats, previous studies revealed, and sometimes flew in front of masquerading animals or bumped into them rather than landing.
This time, the researchers observed the behavior of the flies around the horses wearing gray coats, striped coats and checkered coats, learning that the flies “avoided landing on, flew closer and did not approach too. near striped and plaid rugs “compared to gray, according to Study.
Scientists examined whether the openness effect – the optical illusion that causes us to see the scratches on a barber pole as moving upward rather than just rotating – was a disorienting factor experienced by flies.
“Our results show that this effect does not work – based on the behavior of flies around patterned coats – because if it did, the flies should land on tiles but not on stripes. Checks cannot. replicate the barber pole effect in the eye or brain of a fly, “Caro told CNN.
“It must be something else,” he said.
The performance of the plaid coats was unexpected.
“This suggests that there is nothing special about the stripes per se to prevent horse flies from landing, but it must be the stark contrast between the different elements of the coat,” Caro told CNN.
Future research will focus on the most effective coat patterns and on a better understanding of the role of pattern size and contrast in deterring flies.
Evolution and protection against flies
Protection against horseflies is currently the most widely recognized hypothesis as to why zebras have stripes.
“Horseflies in Africa carry deadly diseases to members of the horse family – the equines. The pressure not to be bitten by these flies is therefore very strong, ”explained Caro.
“Evolution will refine coat shaping based on what is most effective in preventing flies from landing – given the developmental constraints of how patterns develop in utero. Our research and that of our colleagues show that the stripes do this job very well, ”added Caro.
The fact that zebras almost continuously wag their tails and give off a scent that flies also dislike supports the idea that these animals are particularly affected by flies, Caro argued.
“Very few mammals have developed sharp repeating stripes suggesting that zebras suffer particularly severely from horse flies and the diseases they carry,” he told CNN.
Horseflies in the United States
Domestic horses also suffer from horsefly bites, and Sonja Swiger, associate professor in the Department of Entomology at Texas A&M University, said “the consequences are quite serious.”
Tabanid horseflies have a different anatomy than other blood-sucking insects like mosquitoes, which have a needle-like mouth that can penetrate the skin.
“They have very large, jagged mouthparts. They have to punch a hole in the skin for the blood to start flowing, and then they drink it,” Swiger explained.
The “disorderly eating habit” of tabanides causes pain and discomfort in animals such as horses and cattle, and exposes them to the transmission of diseases, including equine infectious anemia.
Horseflies are found across the United States, but are more prevalent in warmer climates, Swiger said. Southern states can have two generations of horseflies each year, while in northern regions there will usually only be one, she explained.
Containing horseflies is “almost impossible,” according to Swiger.
Chemical pesticides are not helpful because flies usually bite once a day, not giving pesticides enough time to be effective. A blanket or coat is an effective tool, and for this reason, the Bristol scientists’ study is exciting and promising, Swiger said.
Do horseflies bite humans? While we’re not their first choice, they do, Swiger said. On your next day on the farm or on a horseback excursion, you may want to wear striped or checkered patterns yourself. You will be stylish and potentially bite-free.
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