Three additional but more speculative points may be made in closing. A “leave” was when the fly made a direct and accelerating flight away from the host ending out of the camera’s field of view. Probing was defined as lowering the head and thorax thereby tilting the abdomen up vertically or obliquely. Also shown are mean landings per minute and hours being filmed. In contrast, zebras tail-flicked more frequently than horses ( respectively, F1, 9.597 = 48.461, p < 0.0001 controlling for individual equid and temperature), and in response to flies, they were less likely to remain stationary (Ns = 147, 285 video clips respectively, 85.0% vs 100% respectively) and instead walked away briskly (10.2% vs 0%) or ran away from flies (4.8% vs 0%) (Chi square = 44.94, df = 1, p < 0.0001, combining these move away categories). https://doi.org/10.1371/journal.pone.0210831.g002. Scientists have proposed more than a dozen ideas to explain why zebras evolved stripes. Davis Department of Wildlife, Fish and Conservation Biology. All rights Reserved. Red arrows indicate direction of flight. Read: To lions, zebras are mostly gray That leaves the fly idea. In retrospect, the failure to find differences in approach towards striped and unstriped objects is unsurprising because tabanids are thought to use odour rather than visual cues to locate hosts at a distance [26] and only switch to vision when close up.

The antennae are longer than most other beetles' antennae, and can even be longer than their body. Finally, there are no thermoregulatory benefits to striping based on controlled experiments using water drums [4], infrared photography of free-living herbivores [3] and logical argument in regards to flank striping [8]. Data Availability: All relevant data are in the paper and its Supporting Information files. But a recent study showed that water drums cloaked in zebra pelts heat up just as much as those covered in normal horse skins. The flies attacked all the horses’ uncovered heads at the same rate. 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. When helpless cows are the victims of fly bites, it stings the humans who own them, too. In addition to stripes preventing landing attempts, we found that when a tabanid did land, it spent less time on a zebra than on a horse and was less likely to probe for a blood meal per landing. The water-based paint faded within a few days, so while it's a less invasive solution than a pesticide-laced ear tag, it's a short-term one. Figure B. Blue arrows show the end position of the approach and start position of the leave phases of flight. Make like a zebra to avoid insect bites, scientists say While unpainted cows and cows with black stripes endured upward of 110 bites in 30 minutes, the … AAAS is a partner of HINARI, AGORA, OARE, CHORUS, CLOCKSS, CrossRef and COUNTER. Submit a letter to the editor or write to [email protected].
Aeres University of Applied Sciences, Almere, Netherlands, Affiliation I think it’s a great piece of work.”. “March flies and other biting flies have huge eyes and vision is important for finding animals to bite and suck their blood,” he said. But the scientists from Britain and California sought to examine that question by studying both horses and zebras at the Hill Livery in Britain, which works with zoos in Europe on conservation for zebras. Compared to horses, flies approached zebras more quickly in terms of speed (median 13.21 [interquartile range 5.04] pix/frame vs. 17.76 [26.9] pix/frame respectively; Mann-Whitney U test, W = 289; p = 0.017) but their tortuosities were similar (1.19 [0.57] vs. 1.07 [0.48] respectively; W = 540; p = 0.18). That rates of stamping, nibbling and scratching were greater for horses but not significantly so may reflect the fact that the latter two sets of behaviours often followed fly departures rather than being instigated by them. In 2014, Caro and his colleagues showed that striped horses—three zebra species and the African wild ass with thin stripes on its legs—tend to live in regions with lots of horseflies. They are often large and agile in flight, and the females bite animals, including humans, to obtain blood. “It’s one of those pieces of research that you say, ‘why hasn’t someone done this before? Something’s clearly throwing them off, but the details are still a mystery. Yes

Striping is also a species specific trait and also under partial genetic control (as witnessed by mother-offspring striping similarities, for example, TC pers obs). Unfortunately, detailed observations of biting flies in the vicinity of live zebras have so far been unavailable but such information would help elucidate the stage at which stripes exert an effect on host seeking by biting flies. Analyses revealed that environmental variables showed fewer significant effects on the behaviour of tabanids than we expected. By comparing these two species, as well as horses that were comically cloaked in zebra-striped coats, the team found fresh evidence for what Caro thinks is the only plausible explanation for the striking stripes: They evolved to deter bloodsucking flies. Many functional hypotheses on the striped pattern of zebras were generated in scientific researches, such as camouflage, confusion of predators, signaling to conspecifics, thermoregulation, and avoidance of biting flies [ 1 ]. 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. Yes Study 1 revealed no significant difference in the rates at which tabanids circled zebras or horses ( respectively, F1, 9.291 = 0.879, p = 0.372 controlling for individual equid and wind speed; Table Ba in S1 File). Another hypothesis says that the black stripes heat up faster than the white ones, setting up circulating air currents that cool the zebras. Rates of tabanids landing. Horses and zebras were always kept in separate but adjacent fields and were both observed and videoed on the same days. If UV attracted flies, we would expect many flies on the white coat, intermediate numbers on the striped coat, and few on the black coat. All it takes to repel pests is a new paint job, researchers say. Only five flies landed on the horses dressed in zebra coats during a 30-minute period, whereas more than 60 touched down on those in the solid black and solid white coats in the same time period. Specifically, most sorts of twitching were greater in horses than in zebras (shoulder twitching respectively, F1, 9.141 = 13.173, p = 0.005 controlling for individual equid and windspeed; withers respectively, F1, 9.548 = 19.948, p = 0.001 controlling for individual equid and windspeed, belly respectively, F1, 8.694 = 11.300, p = 0.009 controlling for individual equid and maximum wind gusts; total skin twitching respectively, F1, 9.435 = 26.474, p = 0.001 controlling for individual equid and windspeed). “This phenomenon has been explained as modulation brightness or polarized light,” the authors wrote. To exclude any possible influence of host odour or differential movement in attracting tabanids, we compared the number of tabanids touching and landing on both sides of different coloured cloth coats placed sequentially in random order on seven horses (study 2). Then, focusing attention on those tabanids that actually landed properly, we recorded the number of times that a fly walked over the pelage, or probed for a source of blood. Table Bb. Zebras have a bold black-and-white striped pattern on their body surface. Instead, there is an emerging consensus among biologists that the primary function of contrasting black and white stripes on the three species of zebras is to thwart attack from tabanids, and possibly glossinids, stomoxys and other biting muscoids based on laboratory and field experiments with striped materials [3, 9–12] and on comparative evidence [13]. Either they miss and overshoot the zebras, or they bump into the hides and bounce off. From a distance, the flies were equally attracted to both horses and zebras, with the same number of insects hovering around both types of animals. Help preserve this vital resource. The scientists believe the striped pattern confuses the fly’s motion detection and deters the pests. All rights reserved. Moreover, flies often simply bumped into zebras but fail to land or fly away: data from study 1 showed that a significantly greater proportion of tabanids touched zebras as compared to horses ( respectively, F1, 8.027 = 5.659, p = 0.045 controlling for individual equid and solar radiation) whereas, conversely, a significantly lower proportion landed on zebras than on horses ( respectively, F1, 7.813 = 47.172, p < 0.0001 controlling for individual equid and maximum wind gusts), almost one third fewer on average. Blue stars show points of contact or landings on the equid. This may have been because we did not go out to the farm when the weather was wet or windy, so all our data are from calm weather conditions. 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. A few weeks after Biden was first elected to the U.S. Senate, his wife and 1-year-old daughter were killed in an automobile accident while Christmas shopping. Since fly activity around equids could have been influenced by weather conditions (e.g. PLoS ONE 14(2): We want to hear what you think about this article. Researchers believe painting stripes on to cattle is a world-first and could become an environmentally friendly alternative to pesticides.