The division of labor is very strict in a beehive. The same applies to periods of rest: honey bees sleep with other members of their professional group, as researchers from the University of Würzburg’s Biocenter have discovered.
The activities in a bee colony are highly organized. The insects adhere to a strict division of labor: cleaning combs, feeding the brood and the queen, producing wax and building combs, keeping watch in front of the hive, foraging for nectar and pollen – each of these tasks is carried out by a specific “professional group”.
A forager bee has clamped itself between two combs using its head and the end of its abdomen so it can sleep. This image comes from a hive and was taken using an endoscope with an infrared light.
(Photo: Hobos team)
But what is the situation with periods of sleep and rest? Do these merely represent a lack of activity, where the bees simply do nothing in the location they happen to be in at that time? Or does the bee colony also exhibit sleep behavioral patterns that are specific to their professional groups? This is exactly what happens, as biologists Barrett Klein, Martin Stiegler, Arno Klein, and Jürgen Tautz from the universities of Würzburg and Wisconsin – La Crosse (USA) report in the journal PLoS ONE.
Inside workers sleep in the middle
Young bees that work inside generally sleep in empty cells close to the middle of the hive, usually in the breeding area. They have several sleep periods daily, spread over day and night. “The breeding area is a bustling place around the clock,” says Jürgen Tautz, “so empty cells there presumably offer the least chance of being disturbed while sleeping.”
When bees switch from inside to outside service, their sleep periods are gradually delayed. Tautz explains: “The older the bees become, the less they sleep. As forager bees, they demonstrate a clear day-night rhythm to their sleeping behavior. They then generally sleep outside cells and closer to the edge of the combs. There they are likely to be largely undisturbed at night.”
Initial findings about sleeping insects
Sleep in insects: The door to this research field was opened in 1983. At that time, German zoologist Walter Kaiser presented new findings about honey bees, and Swiss researcher Irene Tobler published a comparable paper about cockroaches.
The fact that non-vertebrates also demonstrate a genuine sleep behavior came as such a surprise back then that many scientists were reticent in their response, as Tautz explains. Würzburg bee researcher Martin Lindauer had found early indications as far back as 1952: During continuous day-night observations of individual forager bees, he noted that they were “idle” at night especially.
“Over time, more and more similarities have emerged between sleep in bees and sleep in humans,” says Tautz. While initially bee sleep was only detected in phases of immobility, scientists later identified periods of sleep of varying depth as well in the flying insects. As in humans, sleep deprivation in bees also reduces their ability to learn and communicate.
Biological function remains unclear
Also common to both is the fact that, like in humans, many questions remain unanswered regarding the biological function that sleep has in bees. Various explanations have admittedly been proposed by the scientific community, but none of them is universally recognized. One hypothesis assumes, for example, that the organism regenerates itself during sleep. Another regards sleep as an energy-saving measure, and a third suggests that during sleep the brain separates important from unimportant information, meaningfully committing the former to memory.
Beehive is monitored online
The Würzburg research team is keen to conduct further studies to find out more about how bees sleep. Tautz’s team will use a variety of tools, including the Hobos system (Hobos stands for “Honeybee Online Studies”): This monitors the activity in a beehive online around the clock using various sensor and measuring techniques, and the values can be retrieved on the Internet: http://www.hobos.de
New sleep posture discovered
Using Hobos, the Würzburg researchers have now also discovered a previously unknown sleep posture in bees: The insects clamp themselves between two combs using their head and the end of their abdomen and leave their antennae and legs dangling relaxed. They can remain completely motionless in this position for up to 30 minutes. Otherwise, bees sleep by simply squatting in one place with their antennae hanging down.
Barrett Klein, Martin Stiegler, Arno Klein, Jürgen Tautz: "Mapping sleeping bees within their nest: spatial and temporal analysis of worker honey bee sleep", PLoS ONE 2014, July 16
Prof. Dr. Jürgen Tautz, Biocenter at the University of Würzburg, T +49 (0)931 31-84319, firstname.lastname@example.org
Robert Emmerich | Julius-Maximilians-Universität Würzburg
An evolutionary heads-up – The brain size advantage
22.05.2015 | Veterinärmedizinische Universität Wien
Endocrine disrupting chemicals in baby teethers
21.05.2015 | Goethe-Universität Frankfurt am Main
Physicists have developed an innovative method that could enable the efficient use of nanocomponents in electronic circuits. To achieve this, they have developed a layout in which a nanocomponent is connected to two electrical conductors, which uncouple the electrical signal in a highly efficient manner. The scientists at the Department of Physics and the Swiss Nanoscience Institute at the University of Basel have published their results in the scientific journal “Nature Communications” together with their colleagues from ETH Zurich.
Electronic components are becoming smaller and smaller. Components measuring just a few nanometers – the size of around ten atoms – are already being produced...
Development and implementation of an advanced automobile parking navigation platform for parking services
To fulfill the requirements of the industry, PolyU researchers developed the Advanced Automobile Parking Navigation Platform, which includes smart devices,...
The world's first electrical car and passenger ferry powered by batteries has entered service in Norway. The ferry only uses 150 kWh per route, which...
On Tuesday, 19 May 2015 the research icebreaker Polarstern will leave its home port in Bremerhaven, setting a course for the Arctic. Led by Dr Ilka Peeken from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) a team of 53 researchers from 11 countries will investigate the effects of climate change in the Arctic, from the surface ice floes down to the seafloor.
RV Polarstern will enter the sea-ice zone north of Spitsbergen. Covering two shallow regions on their way to deeper waters, the scientists on board will focus...
Nanoengineers at the University of California, San Diego developed a gel filled with toxin-absorbing nanosponges that could lead to an effective treatment for skin and wound infections caused by MRSA (methicillin-resistant Staphylococcus aureus), an antibiotic-resistant bacteria. This "nanosponge-hydrogel" minimized the growth of skin lesions on mice infected with MRSA - without the use of antibiotics. The researchers recently published their findings online in Advanced Materials.
To make the nanosponge-hydrogel, the team mixed nanosponges, which are nanoparticles that absorb dangerous toxins produced by MRSA, E. coli and other...
20.05.2015 | Event News
18.05.2015 | Event News
12.05.2015 | Event News
22.05.2015 | Materials Sciences
22.05.2015 | Information Technology
22.05.2015 | Materials Sciences