Don't shoo, fly. Pesky insects vital to the planet, study says.
To many, they're just nuisances, but houseflies, fruit flies and other maligned flying insects are major migratory players that deserve further study, according to new research that calls them a 'vital' part of global ecosystems.
The analysis looks at the order Diptera, which includes more than 125,000 species of what the insect world calls 'true flies.' Despite their abundance and diversity, the researchers write in the journal Biological Reviews, the flies' migratory behavior is not as well studied as that of more 'charismatic' insects such as butterflies.
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National Geographic
21-04-2025
- National Geographic
‘Sharktopus' wasn't the first. These animals also hitchhike on other animals.
Cockroaches that catch a ride on ants. Grasshoppers that climb aboard sheep. Hitchhiking animals are more common than you think. A classic example of phoresy, the remora uses a modified fin that latches onto larger animals like a suction cup. Here three remoras (Remora brachyptera) ride a Chilean devil ray (Mobula tarapacana) off the coast of Santa Maria Island, Azores. Photograph By Jordi Chias, Nature Picture Library Spend enough time in nature, and you will see some weird stuff—from orcas swimming around wearing salmon like hats to wombats pooping cubes. But when Rochelle Constantine saw a nine-foot-long mako shark jet past her research vessel in the Hauraki Gulf off New Zealand with a huge, orange octopus globbed onto its head, she knew she was witnessing something new. 'It was just one of those lucky days,' says Constantine, a marine ecologist at the University of Auckland in New Zealand. While sharks and octopuses may seem like animals that live in the same habitat—the ocean—Constantine says that each occupies very different areas. Mako sharks, for instance, are known for spending most of their time in the mid-water, while the New Zealand octopus is a benthic species, living nearly its entire life on the seafloor. 'So it just makes no sense how these two things found each other,' says Constantine. The researchers observed the duo for about 10 minutes and ultimately decided to nickname them the 'sharktopus'. Eventually, the odd couple swam off. Their fate remains unknown. From scuba diving to set-jetting 'We just let them go on their way,' says Constantine. The octopus-shark duo surprised both scientists and laypeople alike, but the behavior of one animal riding another is well known in biology. It's called phoresy, and it mostly occurs in smaller animals, especially insects and other invertebrates, that can't disperse as well on their own. Octopuses aren't known to practice phoresy, though with all those suckers, they seem especially equipped to do so. 'I guess the things that they might hitchhike on—seals, sea lions, dolphins, and sharks—you know, all of those animals eat octopus,' says Constantine. Animals typically don't practice phoresy with their natural predators, making sharktopus even more mysterious. Phoresy occurs all over the animal kingdom While animals occasionally come into contact with each other through happenstance or accident, phoresy serves a purpose. For example, plenty of creatures rely on hitchhiking to find mates or complete part of their life cycle. 'Dispersal is a key trait and affects things like gene flow and population structure,' says Andrew Bartlow, an ecologist at the Los Alamos National Laboratory in New Mexico. That means that getting from one place to another comes with big stakes for the animal and its ecosystem. In 2020, Bartlow published a review study of phoresy in the journal Biological Reviews. After scouring the scientific literature, he and his coauthor, Salvatore Agosta, found observations of phoresy in at least 13 phyla, 25 classes, and 60 orders of animals. All of which suggests that hitchhiking behavior has evolved many different times across the tree of life. Some classic examples include fish known as remoras, which use a fin modified into a sucker to latch onto larger animals, such as whale sharks, and barnacles that can be found securely fastened to the skin of whales or the shells of sea turtles. (Watch a bold little bird snatch a remora off of the world's largest fish.) But there are also cockroaches that ride ants, copepods that ride jellyfish, fairy shrimp that ride trout, water fleas that ride wild boar, millipedes that ride birds, sea anemones that ride crabs, and grasshoppers that ride sheep. Not to mention mites, which make up the vast majority scientific knowledge on phoresy. 'There are so many mites,' says Bartlow. Hitchhiking has its risks Catching a lift on a much larger animal has its tradeoffs. Imagine being a pseudoscorpion—a tiny arachnid the size of a pinhead. Unlike their scorpion cousins, pseudoscorpions lack venomous tails, but they do have similar-looking claws which they sometimes use to cling to larger insects, like the harlequin beetle. By grabbing hold of these beetles, pseudoscorpions don't just get a free ride to a new neighborhood—they receive targeted delivery, as the beetles they associate with are freshly transformed adults, who are themselves in search of newly fallen ficus trees, where they lay their eggs. What's more, each beetle can carry multiple pseudoscorpions while in flight, which means the morning commute is also a great place for pseudoscorpions to find mates. Males will even do battle with each other on the backs of these beetles, knocking rivals off whenever they get a chance. And once one male has monopolized the ride, he can woo any females aboard and even begin the process of fertilizing their eggs. Pseudoscorpions are known to hitch rides on larger flying insects, like harlequin beetles. Photograph By Andrés Better Pseudoscorpions, like this Chthonius ischnocheles from the United Kingdom, are tiny arachnids that have scorpion-esque claws. But for the pseudoscorpions who get knocked off in flight? They'll likely be stranded who knows where. The jungles where these animals live are vast, and full of hungry mouths. 'The risks are quite enormous,' says Bartlow. And the same risks apply to mites riding a migrating bird, or crustaceans known as ostracods riding a frog from bromeliad plant to bromeliad plant—fall off at the wrong time, and you might wind up in a habitat you cannot survive in. 'Using frogs as a mode of transport is beneficial because it allows microorganisms to reach environments where they can survive,' says Alan Pedro de Araújo, an evolutionary ecologist at State Department of Education in Goiás, Brazil. 'Alternatively, they can be d by wind or rainwater, but these methods are highly random and unreliable,' he says. 'Without frogs, the success of their migration would be significantly reduced. The dark side of phoresy Phoresy is extremely common among mites. Here flower mites are visible on the beak of an Ecuadorian hillstar hummingbird (Oreotrochilus chimborazo), as it drinks nectar from a flower. The mites use the hummingbird as transport to move from flower to flower, where they feed on nectar and flower tissues. Photograph By Jim Clare, Nature Picture Library Even with as many examples as Bartlow managed to find, he says there are probably tons more waiting to be discovered. For instance, the ocean seems to be underrepresented in observations of phoresy, likely because it's much more difficult for scientists to study what happens below the waves. Scientists are also still trying to understand how phoresy works. For example, in some species, the relationship between the rider and its host can veer towards the macabre. 'Some barnacles are more parasitic than others,' says Bartlow. Likewise, when freshwater mussel larvae latch onto the gills of the fish who will carry them upstream, the baby mussels also begin to leach nutrients from their hosts, like tiny vampires. 'These things are on a spectrum,' explains Bartlow. But ultimately, scientists suspect phoresy can lead down an evolutionary path toward parasitism. As for the so-called sharktopus, the jury is still out on exactly how or why the cephalopod might have found its onto the Mako shark's noggin and whether this example truly counts as phoresy or a chance encounter. Even after a few weeks of media attention and people coming out of the woodwork to offer similar stories on social media, Constantine says they're no closer to solving the mystery. 'There's been a huge amount of media around us,' says Constantine. 'There is not one single explanation for what we've seen.'
Washington Post
12-04-2025
- Washington Post
Don't shoo, fly. Pesky insects vital to the planet, study says.
To many, they're just nuisances, but houseflies, fruit flies and other maligned flying insects are major migratory players that deserve further study, according to new research that calls them a 'vital' part of global ecosystems. The analysis looks at the order Diptera, which includes more than 125,000 species of what the insect world calls 'true flies.' Despite their abundance and diversity, the researchers write in the journal Biological Reviews, the flies' migratory behavior is not as well studied as that of more 'charismatic' insects such as butterflies.
Yahoo
21-10-2024
- Yahoo
Flies with shorter eye-stalks act aggressively because females are less attracted to them
In the stalk-eyed fly world, it's the males with longer eyestalks that get the females. Not only do the females prefer males with longer antennae dotted eye-stalks, but other males are also less likely to fight with these more well-endowed flies. However, some males will always have short eyestalks due to a copy of the X chromosome that causes the eyestalks to be smaller. While investigating why this genetic mutation hasn't disappeared–despite generations of sexual selection–a team of scientists found that the flies might be compensating for their shorter eyestalks with more aggression. The findings are detailed in a study published October 21 in the journal Frontiers in Ethology. 'These driving X chromosomes are pretty interesting because they are an example of how parts of our genetic code aren't necessarily working together, but have their own selfish interests,' study co-author and State University of New York–Geneseo biologist Josephine Reinhardt said in a statement. 'This is an extreme example, but simply carrying one of these selfish chromosomes impacts so many parts of these animals' biology, even their behavior.' Gene drives and dueling flies Stalk-eyed flies is a catchall term for the insects in the fly family Diopsidae and order Diptera. They are typically found among low-lying vegetation in humid areas, generally near rivers and streams. They are only about a centimeter long and feed on decaying animals and plants. Two types of X chromones are present in stalk-eyed flies. The one carrying the mutation for short eyestalks is a driving X chromosome, or more specifically, a meiotic driver. This means that it carries alleles which are over-represented in a male's sperm, so it is much more likely to be passed on to the next generation. 'The driving X chromosome has a huge natural advantage because it passes itself on more than the fair 50-50 'coin flip' rule of genetics that most of us learned in high school biology,' said Reinhardt. 'Up to 100% of a male's offspring end up inheriting the X and therefore are female. Because of this, we might assume the X will keep increasing in the population and even cause extinction. Since that hasn't happened, we're interested in understanding what other traits could counteract that advantage.' To defend their access to mates, male stalk-eyed flies generally use intimidating physical displays and fighting. They will also display more aggression against other flies with similarly-sized eyestalks As a way to test whether the flies carrying the driving X are more aggressive, the team on this study used populations of flies carrying either type of X chromosome–the one that always results in flies with shorter eye stalks and the one that does not. They also matched up competitors with similar eyestalks, recorded their contests, and analyzed their behavior. The fighting behaviors were more common when the two flies had more closely matched eyestalk sizes. These aggressive actions were also seen more often in male flies with the driving X. The males that deployed more of these fighting behaviors were also more likely to win in these contests. Males with the driving X chromosome were also more likely to come out victorious when they engaged in more fighting than displaying. 'When fighters are mismatched, fights tend to end quickly, with the smaller male retreating,' Reinhardt said. 'When a male with the driving X chromosome is fighting a male with similar-sized eyestalks, he is more aggressive. But because driving X males are on average smaller, it is likely still a disadvantage.' Mating opportunities According to the team, this feisty behavior might explain why the flies with short eyestalks were able to mate. Since longer eyestalks signal a larger body size and potentially more dangerous foe, the flies with shorter eyestalks will typically retreat from contests with these bigger flies. However, if males with the driving X chromosome are more aggressive or fail to accurately assess the threat from other males, they might choose to compete with males with longer eyestalks. This then brings them into contact with the females that are initially attracted to their opponent. While this extra aggression is potentially dangerous, it may also give the flies access to mating opportunities that they otherwise wouldn't. Still, this can't fully counterbalance sexual selection. The team's modeling of the spread of the driving X suggests it might explain why the shorter eyestalks haven't taken over. The females still prefer males with longer eyestalks, keeping the variant's frequency low. 'I would say that this study is an initial finding,' said Reinhardt. 'A larger study might be done in which we specifically test for the increase in high-intensity behavior that we saw here in a larger sample. In addition, this is a laboratory study, so it is not totally clear how well it would apply to field behavior.' The study also didn't test female flies. If the driving X chromosome is what directly increases aggression, it might impact females. However, if it's an indirect effect to do with the eyestalk size, the driving X chromosome might not affect the females.
