Bees may have visual capabilities far more diverse than previously thought, with some smaller species displaying visual resolution superior to that of the honey bee. The conclusion results from a new study by researchers at Lund University and Adelaide University, published in the journal Proceedings of the National Academy of Sciences (PNAS).
For decades, the honey bee has been one of the main species used to study insect vision. However, it represents only one of about 20,000 bee species on the planet, and researchers sought to determine whether the visual abilities observed in this species are representative of the others.
To do this, they analyzed the visual abilities of bumblebees and of three species of solitary bees, which live individually rather than forming large colonies led by a queen. By recording the electrical signals produced by light-sensitive cells in the insects’ eyes, the researchers were able to estimate the minimum size of objects they can detect and their visual resolution.
The four species analyzed displayed a visual resolution higher than that observed in the photoreceptor cells of worker honey bees. Among them stood out the small Australian blue-banded bee (Amegilla murrayensis), easily identifiable by the blue or blue-grey bands on the abdomen.
“We were particularly surprised by the fact that the small blue-banded bee could detect objects as well as the drones of honey bees, despite being much smaller,” says Elisa Rigosi, a biology researcher at Lund University.
The drones of honey bees are known for their exceptional visual ability, essential for locating and pursuing queens during mating flights. The fact that a solitary bee much smaller can achieve similar performance suggests that larger eyes are not the only way to achieve higher visual precision.
The researchers also analyzed the relationship between visual performance and the eye structure, including the size of the lenses, the organization of the light-sensitive cells, and how the compound eyes represent visual space. The results indicate that different bee species have developed distinct solutions to achieve high-quality vision.
“There is no single recipe for good vision in bees. Different species have arrived at different combinations of features that allow high visual performance,” explains David O’Carroll, Professor of Biology at Lund University.
The study contributes to a broader understanding of the evolution of vision in bees and other pollinators, also showing how focusing research on a small number of species may overlook important visual capabilities.
The findings may also have applications outside biology. The different solutions developed by evolution to enable precise vision could inspire artificial vision systems and bio-inspired robotics, areas that seek small and energy-efficient sensors capable of detecting and processing visual information.
Steven Wiederman, associate professor at Adelaide University, believes that bee vision is far more diverse than previously thought.
“Honey bees have shaped much of what we know about insect vision, but they are only one of thousands of bee species,” he says.
“By studying a greater diversity of bees, we are discovering that there is no single model for good vision – even very small bees may have extraordinarily sophisticated visual systems,” he concludes.
