Bumblebees thrive in the city but struggle on the farm
News and notes about science
The bumblebees of London may be faring better than their relatives in the English countryside, suggests a study published recently in Proceedings of the Royal Society B.
“We’re not saying from this that urban areas are the solution to bumblebee declines or that urban areas are the ideal habitat,” said Ash Samuelson, a graduate student at Royal Holloway University of London in Britain and lead author of the study. “But given the choice of two unnatural situations, they’re actually able to exploit that city environment, which is very different to what they evolved in.”
Bumblebees are important pollinators for flowers and crops that benefit from their vibrating pollination style. But pesticides, disease and habitat loss are wiping out all types of bees, worldwide. People have noticed more bumblebees buzzing around cities. Samuelson wanted to know if bees were simply traveling to cities when agricultural fields ran out of food or if they actually were surviving better there and having more babies.
Some biologists have suggested that cities may provide refuge for bees.
But there were reasons to think urban living wasn’t great for the bees. Some flowers in cities may be prettier to people than they are rewarding or attractive to bumblebees. Competition with other pollinators can be tough. Crowds are dangerous: parasites are found more heavily on bumblebees in urban areas.
So Samuelson’s team collected more than 100 wild, foraging queen bees and took them back to the lab to build colonies. Then they transplanted the colonies to 38 different sites.
Compared to those placed in cities and villages, colonies placed in agricultural fields produced fewer reproductive offspring and fewer workers, and their queens died sooner. Their colonies, which broke down faster than city and village colonies, also had fewer nutrient reserves.
But even more remarkable was that suburban colonies were no better off than city colonies.
Perhaps modern farm life — with fewer floral resources and potentially more pesticides — may be too stressful for the bees.
The new research offers a relief and a warning: It is positive that bumblebees can exploit city resources, but agricultural fields of the future should be more bee friendly. That may require extra landscaping for farms; research has shown that planting wildflowers or flowering hedgerows near crop fields can help restore pollinator habitat and foraging opportunities.
— Joanna Klein
Japanese spacecraft reaches target, but touchdown is still ahead
Here’s the mission for Japan’s Hayabusa2 spacecraft in a nutshell: Fly to a carbon-rich asteroid between the orbits of Earth and Mars, study it for a year and a half and then bring back some pieces for additional study on Earth.
The Hayabusa2 was launched in 2014. On June 27, it reached its target, and is now some miles above Ryugu, an asteroid about half a mile wide. The Japanese astronomers studying it say it has the shape of a top or even an abacus bead.
Ryugu, as dark as coal, is a carbonaceous asteroid, meaning it is full of carbon molecules known as organics including possibly amino acids, the building blocks of proteins. Such molecules are not always associated with biology and can form from chemical reactions in deep space, but asteroids could have seeded Earth with the organic matter that led to life.
If it stays on schedule, by the end of July, Hayabusa2 will descend within 3.1 miles of Ryugu’s surface to measure the gravity field around the asteroid. In September or October, Hayabusa2 is to make its first “touchdown operation” on the asteroid.
At that point, it may deploy one or more of the three tiny rovers it is carrying. It may also deploy a European-built lander then.
Then it’ll take a hiatus in November and December, because the sun will be directly between Ryugu and Earth, blocking communications.
After that, the spacecraft will make a couple more touchdowns, as well as dropping a copper projectile into the asteroid to create a crater. That will allow the spacecraft to collect some material from beneath the surface.
At the end of 2019, Hayabusa2 is to leave the asteroid and head back to Earth. As it flies by in 2020, it’ll drop off a capsule with the asteroid samples.
— Kenneth Chang
The real killer of Pompeii’s ‘unluckiest man’
He was known across the internet as “Pompeii’s Unluckiest Man.” But the story that spread about his demise may have been greatly exaggerated, a new finding suggests.
In May, archaeologists uncovered the remains of a man who had been seemingly crushed by a flying boulder while fleeing from the eruption of Mount Vesuvius in A.D. 79. Only his skeletal legs and lower torso protruded from beneath the 600-pound block.
At the time, the team reported that a volcanic cloud had launched a stone door jamb toward the man, decapitating him.
But further digging has unearthed the man’s intact skull with his mouth wide open (and full of teeth), suggesting he was not crushed by a volcanic projectile. The skull and the man’s upper torso and arms were found about 3 feet nearly directly below the rest of the body and the gigantic stone. The team said they knew the bones belonged to the same person because of their proximity to each other and because the two halves matched up.
“The death of the victim arrived not because of the block falling on the skull,” said Massimo Osanna, director of the Pompeii archaeological site. “Our new hypothesis is that he died from asphyxiation from the pyroclastic flow.”
The team had already determined that the man, thought to be around 35 years old, had a physical defect that caused him to limp. It is possible the disability slowed him down, making him more vulnerable to the incoming noxious gas and ash. He was one of about 2,000 known victims from the eruption.
The team thinks the upper part of the man’s torso became separated from the lower half sometime from 1748 and 1815 when Naples was under the control of the Bourbon dynasty. During this time, archaeologists often dug tunnels into the ash. Osanna and his team thinks the excavators may have dug a tunnel beneath the skeleton that eventually collapsed, causing the skull and upper torso to fall.
The team is not sure when the block fell over the body. One hypothesis is that the man was in or near a building during the eruption when he suffocated and died. The walls — and the large stone block — may have collapsed at the same time or later and fallen over the deceased body.
— Nicholas St. Fleur
As space aliens go, Oumuamua is kind of a dud
It came from outer space, zooming through the solar system at 50 miles a second last October: a lazily spinning reddish cigar-shaped rock named Oumuamua.
It was an interstellar something, but what, exactly? Some astronomers turned radio telescopes on it just in case it was an alien spaceship, but it was silent.
Astronomers had long considered that interstellar debris might invade the solar system from time to time, in the form of icy chunks spit from the rocky disks forming faraway planets — that is to say, as interstellar comets. And they would come in on weird orbits like Oumuamua did.
But Oumuamua never lit up like a comet on its passage past the sun and through our realm, and so astronomers concluded that it was an alien asteroid.
Now, however, the same team that discovered Oumuamua has concluded that it was a comet after all.
The key to this conclusion comes from an analysis of Oumuamua’s trajectory as measured by a variety of telescopes by Marco Micheli of the European Space Agency’s SSA-NEO Coordination Centre, in Frascati, Italy. Micheli found that the gravity of the sun and planets was not the only force acting on the little wanderer. Something else was pushing the object away from the sun.
Such “nongravitational” forces caused by the outgassing of gas and dust are characteristic of comets.
Unlike asteroids, which are mostly rock, comets are sometimes called “dirty snowballs,” conglomerations of various kinds of ices along with rock and dust. When they get close to the sun, these ices vaporize, carrying gas and dust into a cloud around the comet nucleus. The gas shoots up in little geysers or jets, that act like the thrusters on a spacecraft.
As Micheli explained in an email, these jets are typically on the sunward side of the comet. So as a typical comet approaches the sun, the jets cause a braking effect so the comet falls a bit more slowly than it would if only gravity was pulling it toward the sun.
The astronomers only observed Oumuamua on the outward part of its journey, when it was going away from the sun, however. As Micheli said, “the object is receding from the sun and slowing down, and the outgassing effect acts in the opposite direction, and speeds it up a bit.”
That is exactly what Oumuamua seems to have done, according to Micheli’s analysis.
— Dennis Overbye
Using DNA mapping to find salvation for bigleaf maples
Forests are disappearing. Maps show shrinking woodlands all over the world. Even trees coveted for their wood that are protected from logging are chopped down.
Worried about such deforestation, environmental advocates are driving a project to create a DNA database of populations of the bigleaf maple tree on the West Coast. The eventual goal is to use DNA mapping to combat the thriving black markets for timber in tropical countries that are plagued by illegal logging.
“We are taking leaf tissue from the maple trees and taking samples along the entire length of the species range from Southern California to British Columbia,” said Meaghan Parker-forney, a science officer with the World Resources Institute, a nonprofit group that promotes environmental sustainability and is working on the monthslong initiative.
The DNA database is an experimental project for Norway, which is jointly funding the effort with the U.S. Forest Service’s international program. Norway hopes to see whether such a database is feasible in places like Indonesia and Peru, where illegal logging is rampant.
Using volunteers from Adventure Scientists, a nonprofit organization that specializes in outdoor data collection, the World Resources Institute has recorded different populations of the bigleaf maple, and the unique characteristics of each population.
Environmental advocates hope that DNA databases could be used for legal cases. Several people in the United States have been convicted of illegal logging using DNA evidence. Genetic markers can indicate whether a tree was logged from a protected location.
“If someone came to us and told us their wood came from Washington state and it in fact did not, we would be able to say if the wood they were declaring came from a legal location, or we could say that in fact that is not where it came from,” Parker-forney said.
Collecting the DNA is fairly simple. Volunteers are trained online by Adventure Scientists and use an app to log information in the field. Nineteen volunteers have collected DNA samples for the tree project.
— Sandra E. Garcia