By zeroing in on individual comb cells in honeybee hives, researchers have captured highly detailed footage of the insects, offering valuable insights into bee behavior that has remained largely hidden inside the hive, including rare behaviors that have never been recorded.
The study, published March 17 in PLOS ONE, provides the first digital footage repository of bee behaviors that, while largely known to scientists and beekeepers, had not been filmed well before, instead being described through illustrations or written accounts.
"This study has a unique design, since it is not focused on a problem or something specifically that has not been described before," said first author Paul Siefert, a research assistant at Goethe University Frankfurt's Bee Research Institute Oberursel. "Since there is no platform or study that I know of that uses video-based descriptions of within-hive behaviors, we made 18 videos with 35 minutes duration available for beekeepers, the scientific community and the general public."
While honeybees live in large aggregate hives, the function of the hive relies on complex individual behaviors, orchestrated by hosts of pheromones. Bees are divided into several different castes that determine their behavior and function in the hive, giving them one of the highest levels of social complexity in the animal kingdom.
And while it is relatively easy to observe and analyze the behavior of forager bees, which gather nectar from flowers outside the hive, it is much more difficult to observe behavior inside the hive, as attempts to set up and photograph bees can disrupt these behaviors.
While this study is not the first attempt to digitally record bee behavior, it is a leap in sophistication over previous efforts by scientists. Siefert explained to The Academic Times that the most recent example of a similar study he found was from 1987, when the technology was not available for high-quality recordings or wide sharing of video data.
Siefert and his colleagues at the Bee Research Institute have been making a more modern attempt to digitize bee behavior over the last few years with a sophisticated new filming technique. The method involves focusing on individual comb cells and rotating the hive frames 90 degrees relative to the camera to get a profile view of the bees entering and exiting the cells. The whole method depends on a special glass observation hive, where the team housed a group of about 3,000 bees and a single queen, a small population by bee standards.
"I also did a ton of research and pre-experiments about suitable lighting conditions to record through glass and avoid reflections, and about the complementary camera and its objective," Siefert said. "Furthermore, I compared and tested software and hardware components for long-term video recordings of [satisfactory] quality."
While their previous work with this technique focused on the effect of insecticides on nursing behavior, in this study, the researchers analyzed social behavior of the bees. Their results photographically confirmed known bee behaviors, such as using wax to remodel comb, caring for the brood, grooming each other and behaviors involved in storing pollen and nectar. They also observed several behaviors that had not been recorded in bees, including mouth-to-mouth feeding and unusual patterns of pollen movement.
"I observed a couple of behaviors that I knew existed, but had never seen before," Siefert said. "Others I did not expect to see, such as when pollen was pushed into to the cell by the same forager that unloaded it. This is usually done by housekeeping bees, not foragers."
While Siefert maintains that his study "has a dominant methodological component," he does hope that the resources his team has generated will prove useful for scientists studying bee behavior and toxicology, as well as for educators.
"A primary goal is to educate the public and, in turn, raise awareness about the insect and pollinator decline," he said. "In Europe we have more than 75% decline in total flying insect biomass over the last 27 years. Insects are important for plant pollination and are the basic food resources of many vertebrates."
And, as a passionate entomologist, Siefert believes his footage will help people see bees in a new light.
"Beware," he said, "you will definitely fall in love with honeybees if you observe them closely. How can they be so intelligent?"
The study, "Honey bee behaviours within the hive: Insights from long-term video analysis," published March 18 in PLOS ONE, was authored by Paul Siefert, Nastasya Buling, and Bernd Grünewald, Goethe University Frankfurt.