Seek and you shall find – bees remain excellent searchers even when sick
Scientists have found that honeybees exhibit a characteristic flight pattern to explore their surroundings, even when affected by disease.
Honeybees learn the position of landmarks around their hive as they explore, which helps them find their way to rewarding flower patches and home again. When they first venture outside the hive, or when a beekeeper moves them to a new location, honeybees perform ‘orientation flights’ to explore and to identify landmarks efficiently. These orientation flights have an interesting property: the bees alternate between smaller movements of local exploring and occasional longer flights that bring them new areas – a characteristic pattern of exploration known as a ‘Levy flight’, also exhibited by turtles, basking sharks and human hunter-gatherers.
Scientists have shown that honeybee orientation flights stick to this movement pattern, even when the insects were infected with two diseases. To track the flights, the researchers used a harmonic radar with tiny transponders stuck to the bees’ bodies. Scientists carried out the work Rothamsted Research, which receives strategic funding from BBSRC, alongside colleagues from Queen Mary University of London, University of Sussex, University of Exeter and Martin-Luther University in Germany. The team published their study Optimal search patterns in honeybee orientation flights are robust against emerging infectious diseases today in the journal Scientific Reports.
Honeybees are important as pollinators of fruits and vegetables and of wild flowers, but are affected by several diseases. They can cover areas up to 300km squared in search of flowers. To find out more about how disease affects the bees’ movement, the researchers compared healthy bees with those infected either with a microscopic gut parasite called Nosema, or with the deformed wing virus that is spread by varroa mites. Using harmonic radar, they tracked 78 bees as they performed orientation flights.
Although diseased bees still exhibit the characteristic Levy flight pattern, the infections reduced their flying abilities. Bees with Nosema infection flew only half as far as healthy ones, covering just a third of the area, though their flight speeds were similar. Deformed wing virus had little effect on the distances the bees flew. However, the fact that diseases don’t alter exploring behaviour in the same way as, for instance, the time that bees allocate to different tasks, may have a basis in the structure of the bees’ brains.
Dr Stephan Wolf, lead author of the study, said: “These remarkably robust searching abilities indicate that these are not learned but rather are hardwired in the bees, making them robust against pathogens and possibly other stressors and allowing these bees to still contribute to their colony”.
Tags: bees disease funding research Rothamsted Research press release