By combining a robotic system with a beehive, scientists successfully warmed and resurrected a honeybee colony experiencing a perilous winter condition called chill-coma. Beyond revitalizing the frozen bees on the brink of death, the “robotic beehive” also let researchers monitor heat patterns and map colony activity.
Published in Science Robotics, the new system offers a way for beekeepers and environmental scientists to track hive health while these pollinators face the threat of infection from devastating parasites and suffer from erratic, extreme weather events tied to climate change.
“We envisage that systems like ours could play a role in reducing the huge losses that beekeepers face [of] up to 20% of colonies each winter,” said Rob Mills, corresponding author of the study and scientist with the MOBOTS group at École Polytechnique Fédérale de Lausanne. “Colonies can starve in winter even though they have honey reserves in their hive if they are isolated from that honey by cold, and a robot providing a warm pathway to the honey could open up access.”
What's Bugging Bees?
The Western honeybee, or Apis mellifera, is a keystone species that supports countless natural and agricultural ecosystems through pollination. The insects are also indispensable to the commercial beekeeping industry. Yet, these essential animals are increasingly at risk.
“There are various problems that honeybees can face, such as pathogens or environmental toxins, which may start out affecting one or a few bees but end up impacting a whole colony,” said Mills.
The honeybee’s most famous nemesis is Varroa destructor, a parasitic mite that also carries harmful viruses. Bee colonies under attack by varroa mites become stressed and more susceptible to other dangers, including winter cold.
Since honeybees are cold-blooded, or ectothermic, they bunch together to keep warm over winter. They move collectively in a cluster around the hive to locate and eat stored honey, as well as find the spots that are best insulated from the outside.
“In the core region of the cluster, temperatures are much warmer than in the periphery, creating an optimal microclimate for honeybees within,” explained Donato Romano, scientist at the BioRobotics Institute at Scuola Superiore Sant’Anna, in a Science Robotics Focus discussing the robotic beehive.
Normally when internal hive temperatures drop below 50 degrees Fahrenheit (10 degrees Celsius) bee clusters enter a state called “chill-coma,” in which the bees no longer move or generate their own heat. In weakened colonies – such as those stricken by pests or pestilence – chill-coma can become irreversible and deadly.
Warming the Swarm
To help bees escape chill-coma and prevent colony collapse, Mills and his colleagues built a system made of heat sensors, heating components and a control panel. They designed their device to be easily integrated with many hive types, including box hives often used by commercial beekeepers.
“Unlike previous studies that have altered the temperature surrounding the whole hive to influence bee behavior during winter, our approach involves a focused, gentle temperature stimulus. This slight increase in honeycomb surface temperature can provide thermal energy directly to the bees, reducing their reliance on their own energy reserves by simulating conditions they could naturally generate themselves,” said Martin Stefanec, co-first author of the study and doctoral researcher at Karl-Franzens-Universitat Graz's Institute of Biology.
Adding the technology to an active beehive let the researchers thermally track the cluster’s movement. This newfound access to previously unobtainable data about honeybee thermal activity could be helpful for diagnosing weakened colonies proactively.
“Not only [does] this show colony dynamics never reported before, but also emphasizes that robotics is a powerful tool for exploring biology,” said Rafael Barmak, co-first author of the study and doctoral researcher with the École Polytechnique Fédérale de Lausanne’s MOBOTS group.
Furthermore, by using the device to warm different parts of the nest, the team could control where the colony went, guiding them around the hive to different areas with more resources.
“Our technology also allows us to subtly assist the colony during difficult times, such as guiding them away from areas without honey and towards previously inaccessible reserves,” said Stefanec.
Since the study was carried out during the winter, the scientists were able to catch when a hive of about 4,000 bees fell into chill-coma and resurrect the cluster through heating. Although the queen died in the time between chill-coma’s onset and device activation, the leaderless colony still survived for another two months of winter because of additional thermal assistance. Moving forward, the group hopes to examine how the robotic beehive can assist colonies during in other scenarios.
“We already started to investigate collective behaviors that happen during the summer season,” said Barmak, noting that bees regulate nest temperature to support the health of their baby brood. “Another interesting aspect we would like to study is how the thermal capabilities of our robotic system could be used to detect and treat the almost omnipresent parasite Varroa destructor.”