Posts tagged honeybees
Articles and news from the latest research reports.
Bee dance points the way
QBI scientists at The University of Queensland have found that honeybees use the pattern of polarised light in the sky invisible to humans to direct one another to a honey source.
The study, conducted in Professor Mandyam Srinivasan’s laboratory at the Queensland Brain Institute, a member of the Australian Research Council Centre of Excellence in Vision Science (ACEVS), demonstrated that bees navigate to and from honey sources by reading the pattern of polarised light in the sky.
“The bees tell each other where the nectar is by converting their polarised ‘light map’ into dance movements,” Professor Srinivasan said.
“The more we find out how honeybees make their way around the landscape, the more awed we feel at the elegant way they solve very complicated problems of navigation that would floor most people – and then communicate them to other bees,” he said.
The discovery shines new light on the astonishing navigational and communication skills of an insect with a brain the size of a pinhead.
The researchers allowed bees to fly down a tunnel to a sugar source, shining only polarised light from above, either aligned with the tunnel or at right angles to the tunnel.
They then filmed what the bees ‘told’ their peers, by waggling their bodies when they got back to the hive.
“It is well known that bees steer by the sun, adjusting their compass as it moves across the sky, and then convert that information into instructions for other bees by waggling their body to signal the direction of the honey,” Professor Srinivasan said.
“Other laboratories have shown from studying their eyes that bees can see a pattern of polarised light in the sky even when the sun isn’t shining: the big question was could they translate the navigational information it provides into their waggle dance.”
The researchers conclude that even when the sun is not shining, bees can tell one another where to find food by reading and dancing to their polarised sky map.
In addition to revealing how bees perform their remarkable tasks, Professor Srinivasan says it also adds to our understanding of some of the most basic machinery of the brain itself.
Professor Srinivasan’s team conjectures that flight under polarised illumination activates discrete populations of cells in the insect’s brain.
When the polarised light was aligned with the tunnel, one pair of ‘place cells’ – neurons important for spatial navigation – became activated, whereas when the light was oriented across the tunnel a different pair of place cells was activated.
The researchers suggest that depending on which set of cells is activated, the bee can work out if the food source lies in a direction toward or opposite the direction of the sun, or in a direction ninety degrees to the left or right of it.
(Source: qbi.uq.edu.au)
Honey bees may have only a fraction of our neurons—just under a million versus our tens of billions—but our brains aren’t so different. Take sidedness. The human brain is divided into right and left sides—our right brain controls the left side of our body and vice versa. New research reveals that something similar happens in bees. When scientists removed the right or left antenna of honey bees, those insects with intact right antennae more quickly recognized bees from the same hive, stuck out their tongues (showing willingness to feed), and fended off invaders. Bees with just their left antennae took longer to recognize bees, didn’t want to feed, and mistook familiar bees for foreign ones. This suggests, the team concludes today in Scientific Reports, that bee brains have a sidedness just like ours do. The researchers also think that right antennae might control other bee behavior, like their sophisticated, mysterious "waggle dance" to indicate food. But there’s no buzz for the left-antennaed.
You may need a cup of coffee to kick start the day but it seems honeybees also get their buzz from drinking flower nectar containing caffeine.
Publishing in Science, researchers have shown that caffeine improves a honeybee’s memory and could help the plant recruit more bees to spread its pollen.
In tests honeybees feeding on a sugar solution containing caffeine, which occurs naturally in the nectar of coffee and citrus flowers, were three times more likely to remember a flower’s scent than those feeding on just sugar.
Study leader Dr Geraldine Wright, Reader in Neuroethology at Newcastle University, explained that the effect of caffeine benefits both the honeybee and the plant: “Remembering floral traits is difficult for bees to perform at a fast pace as they fly from flower to flower and we have found that caffeine helps the bee remember where the flowers are.
“In turn, bees that have fed on caffeine-laced nectar are laden with coffee pollen and these bees search for other coffee plants to find more nectar, leading to better pollination.
“So, caffeine in nectar is likely to improve the bee’s foraging prowess while providing the plant with a more faithful pollinator.”
In the study, researchers found that the nectar of Citrus and Coffea species often contained low doses of caffeine. They included ‘robusta’ coffee species mainly used to produce freeze-dried coffee and ‘arabica’ used for espresso and filter coffee. Grapefruit, lemons, pomelo and oranges were also sampled and all contained caffeine.
Co-author Professor Phil Stevenson from the Royal Botanic Gardens, Kew and the University of Greenwich’s Natural Resources Institute said: “Caffeine is a defence chemical in plants and tastes bitter to many insects including bees so we were surprised to find it in the nectar. However, it occurs at a dose that’s too low for the bees to taste but high enough to affect bee behaviour.”
The effect of caffeine on the bees’ long-term memory was profound with three times as many bees remembering the floral scent 24 hours later and twice as many bees remembering the scent after three days.
Typically, the nectar in the flower of a coffee plant contains almost as much caffeine as a cup of instant coffee. Just as black coffee has a strong bitter taste to us, high concentrations of caffeine are repellent to honeybees.
Dr Wright added: “This work helps us understand the basic mechanisms of how caffeine affects our brains. What we see in bees could explain why people prefer to drink coffee when studying.”
Dr Julie Mustard, a contributor to the study from Arizona State University, explains further: “Although human and honeybee brains obviously have lots of differences, when you look at the level of cells, proteins and genes, human and bee brains function very similarly. Thus, we can use the honeybee to investigate how caffeine affects our own brains and behaviours.”
This project was funded in part by the Insect Pollinators Initiative which supports projects aimed at researching the causes and consequences of threats to insect pollinators and to inform the development of appropriate mitigation strategies.
Population declines among bees have serious consequences for natural ecosystems and agriculture since bees are essential pollinators for many crops and wild flowering species. If declines are allowed to continue there is a risk to our natural biodiversity and on some crop production.
Professor Stevenson said: “Understanding how bees choose to forage and return to some flowers over others will help inform how landscapes could be better managed. Understanding a honeybee’s habits and preferences could help find ways to reinvigorate the species to protect our farming industry and countryside.”
To bee an art critic, choosing between Picasso and Monet
Honeybees are also discerning art critics, according to scientists from UQ’s Queensland Brain Institute, the UQ School of Psychology and the Federal University of Sao Carlos, Brazil.
The study, published in the Journal of Comparative Physiology A, found honeybees had remarkable visual learning and discrimination abilities that extended beyond simple colours, shapes or patterns.
QBI researcher Dr Judith Reinhard said honeybees had a highly developed capacity for processing complex visual information, and could distinguish landscape scenes, types of flowers, and even human faces.
“This suggests that in spite of their small brain, honeybees have a highly developed capacity for processing complex visual information, comparable in many respects to vertebrates,” she said.
Dr Reinhard and her team investigated whether this capacity extended to complex images that humans distinguish on the basis of artistic style, including Impressionist paintings by Monet and Cubist paintings by Picasso.
“We were able to show that honeybees learned to simultaneously discriminate between five different Monet and Picasso paintings, and that they did not rely on luminance, colour, or spatial frequency information,” she said.
When presented with novel paintings of the same style, the bees demonstrated an ability to generalise, suggesting they could differentiate Monet from Picasso by extracting and learning the characteristic visual information inherent in each style.
“Our study suggests that discrimination of artistic styles is not a higher cognitive function that is unique to humans, but simply due to the capacity of animals – from insects to humans – to extract and categorise the visual characteristics of complex images,” Dr Reinhard said.
Honeybees can bite as well as sting; venom could be anesthetic
Honeybees have defensive weapons at both ends of their bodies, Greek and French researchers have found: They can not only sting their enemies, as has long been known, but they can also bite them, injecting a venom that paralyzes invaders. The venom might be useful as an anesthetic in humans and other animals, the researchers speculate, and a British company has already patented the application and conducted preliminary tests suggesting that the venom works much like the well-known lidocaine.
The discovery was inadvertent. A team led by biologist Alexandros Papachristoforou of the Aristotle University of Thessaloniki in Greece was studying ways to control wax moths. The moths are a serious problem for beekeepers, invading hives, consuming wax and pollen and often destroying the honeycomb. Using natural products on the moths, the researchers tried 2-heptanone, which is produced naturally by the bees. At first, the team thought exposure to the chemical killed the wax moths. “However, on closer inspection, we realized that the wax moths were merely anesthetized for a period of one to nine minutes,” Papachristoforou said. “This was quite unexpected, so our scientific team set up a series of rigorous experiments to find out what was really happening and came up with our remarkable discovery.”
Their findings were published in the online journal Plos One.
Worker honeybees shuttling between foraging and nursing tasks have been found to switch huge groups of genes on and off in their brains for each job. This shows for the first time that different behaviours can have specific gene patterns. The discovery could have implications for how our own behaviour influences which genes are switched on in our brains and bodies.