Dogfighting bees perform aerial combat right at researcher’s front door

Jackson has made a career studying the complex flight behaviors of birds. But when he moved into a new home in Virginia, it was the bees on his porch that caught his eye. He noticed swarms of purplish-black bees -- eastern carpenter bees (Xylocopa virginica) -- hard at work constructing complex nests in the wooden beams of his house. While most people dismiss these insects as home-destroying pests, Jackson has pegged these little drillers as an important study animal for understanding how animals fly.

Carpenter bees intrigue Jackson for their defensive "dogfighting" behaviors. The insects occasionally engage birds or small mammals, but most interactions involve defense against other carpenter bees, who can lay eggs in the other bees' tunnels and mooch off their competitor's metabolic investment.

A defender bee will carefully size-up its opponent and then either chase it away or engage in a grapple, dragging the bee to the ground where other defenders can gang up and finish it off.

Jackson wanted to learn more about these aerobatic melees, and the bees' small size made them ideal for study using simple consumer-grade equipment.

To record the aerial dogfighting events, Jackson used three GoPro cameras to record a flight zone about the size of a single-car garage, enabling him to precisely capture the rapid and complex maneuvers of the brawling bees. This work was done just outside his house in Charlottesville, Virginia, in an area frequently traveled by the bees.

"We're really getting the biomechanics and performance in totally natural settings, which hasn't been done much before, especially in flying animals like bees," he says.

Observation of a volume like this might only capture a few wing beats of a bird in flight, but can tell a much grander story when it comes to insect combat.

So far, Jackson and his students have been able to closely analyze 80 minutes of video, yielding a rich data set of nearly 600 flight paths, with some unexpected twists and turns. Intuitively, it would seem that during aerial combat, the fighter who can fly faster and turn sharper would have the clear advantage over their foe. Most people have seen this demonstrated by birds chasing one another in the air (or by plucky starfighters attacking space stations).

"However," notes Jackson, "a good number of carpenter bee chases occurred at very low speed." In other words, not the "usual" behavior for fights and pursuits between flying animals.

Jackson has seen that two bees will engage in a delicate sparring match as they hover, survey, and make very subtle movements. Eventually the attacker will either leave or make a break for the tunnels, forcing the defender to surrender or move to intercept.

"It's not top speed that wins every time. Clearly something else is going on." Jackson suggests that the insects may be performing a sort of aerial fencing match, which could not have been detected using traditional recording techniques. There has been an increased push in the scientific community toward understanding the intricacies of aerial combat in nature, and Jackson's work provides an important tool for conducting the critical research to uncover the answers.

By developing an effective and affordable system for conducting field studies, Jackson hopes to unravel this bee behavioral quandary and also to enable other scientists to conduct their own studies of dynamic flight behaviors in completely natural settings, a relative rarity in the lab-dominated world of science.

Jackson presented his research at the 2016 annual meeting of the Society for Integrative and Comparative Biology in Portland, Oregon.