Painting cows with zebra stripes cuts insect attacks
Cows painted with white stripes showed 20% reduction in fly-repelling behaviour.
Painting cows with zebra-like stripes may be a simple strategy to keep biting flies at bay. There was over 50% reduction in the number of biting flies seen on legs and body of the cows painted with zebra-like stripes compared with cows that were not painted thus.
As a result of reduced biting fly attacks, the cows painted with white stripes showed 20% reduction in fly-repelling behaviour — foot stamping, tail flicking, skin twitching and head throwing. The results were published in the journal PLOS ONE .
Traditionally, pesticides have been used to control biting flies. Very often insects develop resistance against even newly introduced pesticides. In light of this, the environmental-friendly approach to control biting insects becomes appealing.
Several studies carried out earlier have shown that biting flies affect the behaviour of cattle. These flies can reduce grazing, feeding, and bedding down time of cattle and increase the fly-repelling behaviours of cows.
Japanese researchers painted six Japanese black cows with white stripes to resemble the zebra-like pattern. They used two control groups — black cows painted with black stripes and cow that were not painted with any stripes. All three cows were kept side-by-side and tied to a stake in the ground. They observed each cow in the morning and evening with a total of six observations for each cow. All the three cows were observed simultaneously in sunlight or shade during each observation and photo images were taken.
Painting is generally a short-term measure. “The development of more effective techniques to ensure the persistence of black-and-white stripes on livestock during the biting fly season [three-four months] may be necessary in order to apply this method to animal production sites,” they write.
Studies carried out earlier by painting non-animate objects and covering horses with cloth coats with a striped pattern showed that there were far fewer landings of flies when painted with zebra-like stripes.
Earlier studies by several researchers have attributed reduced landing of biting flies to modulation brightness or polarized light. Others have found insects approaching the target faster and failing to decelerate just before making contact with zebra surfaces. The stripes confuse the flies and as result they are unable to control their approach and landing.
If the shoo fits: cows painted with zebra stripes keep flies in line
Painting a cow to look something like a zebra has been found to reduce fly bites by 50%.
Researchers believe painting stripes on to cattle is a world-first and could become an environmentally friendly alternative to pesticides.
The study, published by Japanese scientists in the journal Plos One, found fly attacks were “significantly reduced” by the disguise. The scientists believe the striped pattern confuses the fly’s motion detection and deters the pests.
In what was a five-minute process for each animal, researchers painted white, 4cm to 5cm stripes on six pregnant Japanese black cows. The stripes were drawn freehand, using “commercial waterborne white lacquers” that faded easily.
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The laquered bovines were then observed. Two of the cows were painted with white stripes, two with black stripes and two were left unpainted for a control. The process then repeated so, over nine days, each cow spent three days striped, painted black or unpainted.
Only 55 flies were observed on the zebra cows, compared with 111 on the black-painted cows and 128 on the control cows.
The ersatz zebras were observed to demonstrate only 40 fly-repelling behaviours (such as flicking their tails and shaking their heads) every 30 minutes, compared with 53 and 54 fly-repelling behaviours in the others.
Previous studies have found that flies are less likely to land on horses wearing striped blankets and other objects painted with stripes. But researchers believe this is the first time cattle have been painted and studied in such a way.
“This phenomenon has been explained as modulation brightness or polarized light,” the authors wrote. Previous studies found that stripes confuse a fly’s motion detection, causing them to approach animals at a higher speed, but also to fail to decelerate properly.
The researchers now say more work is needed, both to confirm the link and to develop less labor-intensive ways of ensuring cows remain patterned and zebra-like. If so, it could ease one of the most persistent pest problems that face cattle.
Flies stop cattle from grazing, feeding and sleeping, and can cause “bunching behaviours”, where cattle jostle for space to escape flies, causing heat stress and injury.
“Biting flies are the most damaging arthropod pests of cattle worldwide,” the report said. “The economic impact of biting flies on the United States cattle production was estimated at $2.2bn per year.
“In future the development of more effective techniques to ensure the persistence of black-and white stripes on livestock during the biting fly season (3-4 months) may be necessary.”
