Darwin was right again—sort of.
- Charles Darwin speculated that wingless insects thrived on windy islands because they weren't blown off the land.
- While the reasoning was slightly faulty, researchers have now proved Darwin's 165-year-old "wind hypothesis."
- This finding is yet another example of how environments shape the animals that inhabit them.
All animals adapt to their environment. Even humans, self-isolating animals that we are, are shaped by our surroundings. Every one of us is interdependent with the environment that we inhabit—it shapes us as much as we shape it.
While the Buddhist notion of interdependence dates back roughly 2,500 years, we didn't understand how profoundly the environment affects biology until Charles Darwin. Now one of his theories, long known as the "wind hypothesis," has been shown to be true. It only took 165 years to verify his observations.
To be fair, the wind isn't the only reason increasing numbers of insects no longer grow wings. But as a new study, published in Proceedings of the Royal Society B, shows, the wind is a major factor in this evolutionary decision.
Not that the world is about to be overrun with unwinged critters. Roughly 95 percent of the world's insect population can fly. After boating around coastal Morocco, Darwin noticed something odd on the island of Madeira: many local beetles (his personal passion) were wingless. He suggested flying beetles would have been blown off the island given the strong winds. He then speculated that apterous (un-winged) beetles were better suited for the environment.
The theory commenced with a bit of a bet between Darwin and his friend, geographical botanist Joseph Dalton Hooker, as explained by lead researcher, Rachel Leihy, a Ph.D. candidate at Monash University's School of Biological Sciences:
"He and the famous botanist Joseph Hooker had a substantial argument about why this happens. Darwin's position was deceptively simple. If you fly, you get blown out to sea. Those left on land to produce the next generation are those most reluctant to fly, and eventually evolution does the rest. Voilà."
Charles Darwin statue
Credit: Christian / Adobe Stock
Monash researchers looked at three decades of data on various insect species living in Antarctica and 28 Southern Ocean islands—including Svalbard, Jan Mayen, Ellef Ringnes, Bathurst, and St. Matthew—and discovered a trend: wind (as well as low air pressure and freezing temperatures) made flight nearly impossible to resident insects. They simply didn't have the energetic resources needed to take to the sky. Better to crawl around and scavenge.
Darwin wasn't completely right. He thought the evolutionary adaptations were due purely to wind throwing insects off the island. But nutrition matters too. Flight consumes a ton of energy. The windier it is, the harder insects have to work. Battling a gale requires an inordinate amount of calories. As the team writes,
"Strong winds can also inhibit normal insect flight activity, thereby increasing the energetic costs of flying or maintaining flight structures. This energy trade-off is more complex than Darwin's single-step displacement mechanism because it requires genetic linkage between traits associated with flight ability, flight propensity, and fecundity or survival."
Still, you have to hand it to the man. During a time when most humans assumed animals were all the result of metaphysical tinkering, Darwin gazed out into nature and connected the dots. His mind has inspired over a century-and-a-half of scientific progress as we continue to build on—and, as this study shows, prove—his theories.
Darwin knew that every animal is the product of its environment, and therefore must respect both its boons and its boundaries. Talk about a lesson we need today. Environments are known to become very hostile to foreign invaders when pushed too hard. Right now, we're courting disaster. Hopefully, we won't wait for evolution to ground our ambitions.
Stay in touch with Derek on Twitter and Facebook. His most recent book is "Hero's Dose: The Case For Psychedelics in Ritual and Therapy."
Mosquitoes can taste your blood using unique sensory abilities. Can we use that to keep them off us?
- A recent study demonstrates that mosquito brains react to the taste of human blood in strange ways.
- Some neurons only activated when presented with all four flavor elements. This is thought to be a unique adaptation.
- The findings may lead to novel ways to prevent mosquito bites.
Female mosquitoes don't usually suck blood—they sustain themselves on nectar, but switch to the red stuff when they need to lay eggs. They work harder to drink blood than nectar, drawing it in with much greater force. How they know the difference between the two has remained unknown, until now.
A new study published in Neuron sheds light on how mosquitoes determine what they're eating and offers a potential solution to their disease spreading ways.
Like many things, it's all a matter of taste.
In a move dubbed a "tour de force" by other scientists involved in mosquito research, the researchers genetically modified mosquitoes so that specific neurons associated with taste lit up florescent tags when activated. They then offered these Franken-mosquitos a variety of tempting drinks to see if they would consume them and, if so, what taste neurons activated.
Sheep's blood was found to appeal to the insects, which consumed it with delight. However, attempts to get them interested in saline or sugar water mixtures that had only single components of blood didn't work, even when the signatures of animals like carbon dioxide or heat (typically used by the parasites as guides towards sources of blood) were added.
To draw them back, the researchers whipped up a blood-like concoction of glucose (sugar), sodium bicarbonate (present in both blood and baking soda), sodium chloride (salt), and adenosine triphosphate, or ATP, a compound that provides energy to cells which is found in all known forms of life. This was a success, and the little parasites flocked to it.
Next, the scientists offered the mosquitoes small tastes of each of the flavor components in the blood mixture to see which neurons reacted. While giving them glucose did not activate any of the neurons associated with the blood-drinking system— perhaps because glucose is also found in nectar—small doses of salt, sodium bicarbonate, and ATP did. Each flavor activated its own set of neurons, similar to how our taste buds react to a specific flavor element.
However, one large cluster of neurons only activated when all four ingredients were present.
According to lead author Veronica Jové, this detection of combinations rather than taste components is a unique adaptation. She explained, "These neurons break the rules of traditional taste coding, thought to be conserved from flies to humans."
And for the curious, the researchers did sample the ATP mixture they prepared in the lab. They didn't taste anything. Presumably, the taste of human blood to mosquitoes is akin to the sight of a flower in all its ultra-violet glory to a honey bee. It's just something we can't sense or hope to grasp. Though, given the sugar and salt element, perhaps to them it is like the sweet and salty flavor of salted caramels or saltwater taffy.
So, can we use this to finally destroy mosquitoes once and for all?
Not quite, but by increasing our understanding of how mosquitoes work, we can figure out how to keep them off us.
Co-author Dr. Leslie B. Vosshall suggests that, just as we give our pets medicine to keep fleas, ticks, and mosquitoes at bay, this discovery may lead to a drug that makes human blood unappealing to mosquitoes for use by those going into infested areas. If they can't taste blood, they may not bite in a way that can spread disease.
Mosquitoes are also known to prefer O type blood over all other types. This study may lead to further ones which help explain why. Additionally, because many neurons did not activate at all when the insects fed on blood or its components, further research will have to investigate if they are associated with still other flavors, or if they are related to the act of feeding on blood in different ways.
Just what every arachnophobe needed to hear.
- A new study suggests some spiders might lace their webs with neurotoxins similar to the ones in their venom.
- The toxins were shown to be effective at paralyzing insects injected with them.
- Previous studies showed that other spiders lace their webs with chemicals that repel large insects.
Everybody knows how spiders catch bugs to eat. They weave a sticky web and wait for something to land in it. These webs are remarkably tough, elastic, and have been the focus of engineers hoping to replicate their properties for years. It all seems rather straightforward, as trap setting goes.
But in a twist that will send a chill down the spine of arachnophobes, a new study suggests that some spiderwebs assure their prey won't get away by adding neurotoxins to their webs.
Just what we needed to know before walking into another spider web
The study, published in the Journal of Proteome Research, was carried out by Biochemical Ecologist Mario Palma of the University of São Paulo State, their Ph.D. student, Franciele Esteves, and their colleagues. They focused on the webs of the striking T. clavipes, also known as the Banana Spider.
These spiders are orb weavers, known for their complex and often large webs. They can have up to seven glands that produce silk for various purposes, including catching prey, shielding themselves, protecting their eggs, mating rituals, and making webbing to walk on.
The researchers examined the spiders' various web producing glands. This revealed a spectrum of neurotoxin-like proteins not dissimilar to those found in the spider's venom present on the silk. On the web, these proteins are suspended in oily, fatty acids.
Following up on this discovery, they tested the proteins' effectiveness on insects. Most of those test subjects were paralyzed less than a minute after exposure, and a few died. These experiences relied on the injection of the proteins rather than on absorption but did demonstrate their capacity. Further tests showed that the fatty acids the proteins reside in could allow them to enter the body of prey insects.
Previous studies demonstrated that some spiders can add certain chemicals to their webs to repel larger insects which could cause the spider trouble. So, the idea that some spiders are adding another chemical to the mix, this time to cause paralysis, isn't too far-fetched.
However, some scientists aren't so sure about all this. They call for further study into the mechanism of action to demonstrate that these proteins cause paralysis and rule out potential other applications.
So, those of you who like animal facts can take pride in knowing that spider webs sometimes have poison in them to stun their prey. Those of you who are terrified of spiders can fear the same information. Either way, walking into a spider web just got even less pleasant.
Certain water beetles can escape from frogs after being consumed.
- A Japanese scientist shows that some beetles can wiggle out of frog's butts after being eaten whole.
- The research suggests the beetle can get out in as little as 7 minutes.
- Most of the beetles swallowed in the experiment survived with no complications after being excreted.
In what is perhaps one of the weirdest experiments ever that comes from the category of "why did anyone need to know this?" scientists have proven that the Regimbartia attenuata beetle can climb out of a frog's butt after being eaten.
The research was carried out by Kobe University ecologist Shinji Sugiura. His team found that the majority of beetles swallowed by black-spotted pond frogs (Pelophylax nigromaculatus) used in their experiment managed to escape about 6 hours after and were perfectly fine.
"Here, I report active escape of the aquatic beetle R. attenuata from the vents of five frog species via the digestive tract," writes Sugiura in a new paper, adding "although adult beetles were easily eaten by frogs, 90 percent of swallowed beetles were excreted within six hours after being eaten and, surprisingly, were still alive."
One bug even got out in as little as 7 minutes.
Sugiura also tried putting wax on the legs of some of the beetles, preventing them from moving. These ones were not able to make it out alive, taking from 38 to 150 hours to be digested.
Naturally, as anyone would upon encountering such a story, you're wondering where's the video. Thankfully, the scientists recorded the proceedings:
The Regimbartia attenuata beetle can be found in the tropics, especially as pests in fish hatcheries. It's not the only kind of creature that can survive being swallowed. A recent study showed that snake eels are able to burrow out of the stomachs of fish using their sharp tails, only to become stuck, die, and be mummified in the gut cavity. Scientists are calling the beetle's ability the first documented "active prey escape." Usually, such travelers through the digestive tract have particular adaptations that make it possible for them to withstand extreme pH and lack of oxygen. The researchers think the beetle's trick is in inducing the frog to open a so-called "vent" controlled by the sphincter muscle.
"Individuals were always excreted head first from the frog vent, suggesting that R. attenuata stimulates the hind gut, urging the frog to defecate," explains Sugiura.
For more information, check out the study published in Current Biology.
Declining bee populations could lead to increased food insecurity and economic losses in the billions.
Bees have endured a disastrous half-century. In the winter of 2018, U.S. beekeepers reported losing 37.7 percent of their honeybee colonies. It was the largest die-off reported since the Bee Informed Partnership began its survey in 2006, yet in that decade, average winter losses of managed colonies were 28.7 percent. That's near twice the historic rate and part of a 50-year trend of declining species richness in wild bees and other pollinators.
That's bad news for the bees and also anyone who depends on the food generated through their labor. That is, all of us. According to the USDA, approximately 35 percent of the world's food crops depend on animal pollinators to reproduce, with some scientists estimating that "one out of every three bites of food we eat exists because of animal pollinators."
That many crops depend on pollination to reproduce is well-established; however, how much pollination proves a limiting factor to crop yield is less understood. If wild bee and managed honeybee populations continue to decline, will the amount of food available to feed us decline, too? That's the question a Rutgers-led team of researchers sought to answer.
From bee to farm to table
A bar graph showing the percentage of pollination limitation for the seven crops studied.
The research team selected seven crops to study: apples, almonds, pumpkins, watermelons, sweet cherries, tart cherries, and highbush blueberries. These were chosen because each is highly dependent on insect pollination for reproduction. The researchers then established a nationwide study across 131 U.S. and British Columbia farms. They selected only commercial farms in top-producing states—for example, Michigan and Oregon farms for blueberries. This way, their sample would represent the conditions and farming practices in which a majority of these crops are grown.
After collecting data on pollinator visitation rates and crop production, the researchers measured the data through three statistical models. They also analyzed the contribution differences between wild bees and managed honeybees as well as the economic value of the bees' service.
"We found that many crops are pollination-limited, meaning crop production would be higher if crop flowers received more pollination. We also found that honey bees and wild bees provided similar amounts of pollination overall," Rachael Winfree, a professor in the Department of Ecology, Evolution, and Natural Resources at Rutgers University-New Brunswick and the study's senior author, said in a release. "Managing habitat for native bee species [and] stocking more honey bees would boost pollination levels and could increase crop production."
Of the crops studied, apples, blueberries, sweet cherries, and tart cherries were hit hardest when pollination decreased. Watermelon and pumpkin yields weren't as limited by pollinators, possibly because these crops sport fewer blooms and flower in summer when the weather is less inclement. Almonds proved the outlier as the crop is the earliest bloomer yet not pollination limited. The researchers speculate that this is due to the almond industry's intense reliance on managed honeybees.
"Our findings show that pollinator declines could translate directly into decreased yields or production for most of the crops studied, and that wild species contribute substantially to pollination of most study crops in major crop-producing regions," the researchers write.
For the seven crops studied, the researchers estimate the annual production value of pollinators to be more than $1.5 billion. They also found that wild bee species provided comparable pollination, even for crops in agriculturally intensive regions.
Their findings were published in the most recent Proceedings of the Royal Society B: Biological Sciences.
Ecological and edible incentives
A protester shows a handful of bees that died by pesticides. The protest was held during the Bayer AG shareholder meeting in 2019.
(PhooMaja Hitiji/Getty Images)
The concern extends beyond these seven. Crops such as coffee, avocados, lemons, limes, and oranges are also highly dependent on pollinators and may prove pollination limited. If declining bee populations are tied to such yields, it could mean barer supermarket shelves and increased prices. While that may only be an annoyance to some, to poor and vulnerable communities who already struggle to secure salubrious, affordable food, such a deficit would present another barrier to the vital micronutrients necessary for a healthy life and diet.
Unfortunately, the threats to bees are numerous. Parasites, agrochemicals, monoculture farming, and habitat degradation all play a role, and neither stressor works in isolation. Sublethal exposure to neonicotinoids, an insecticide, can cause impairments in bees, while monoculture farming serves up a monotonous and unhealthy floral buffet. Both impede bees' immune systems, rendering them vulnerable to parasites such as Varroa destructor, a mite that can transmit debilitating viruses as it feeds on bees' fat bodies. And all of these stressors will likely be inflamed by climate change in the years to come.
Some have proffered mechanical solutions, such as Japan's National Institute of Advanced Industrial Science and Technology where technicians are developing robotic bees. These micro-drones are covered in gelled horsehair and have successfully cross-pollinated Japanese lilies. Other experiments include pollen sprays. However, the large-scale viability of tech-centric solutions seems questionable. After all, wild bees currently perform their ecological services pro bono and are as effective as managed honeybees. Any technological solution implemented in their absence would add to the agricultural costs and likely increase prices anyway.
Ecological amelioration will be necessary. To combat habitat fragmentation and strengthen biodiversity, many cities are implementing green-way strategies. For example, the Dutch city of Utrecht has decked its bus stop roofs with plants and grasses to create bee and butterfly shelters, while other cities are looking to foster bee-friend roadsides. And government initiatives incentivize farmers and landowners to adopt bee-friendly management practices. These solutions aren't only a matter of ecological conservation but also food security and public health.