This month in the Journal of Experimental Biology, Amanda Lohmann (past UNC undergraduate), Aaron Corcoran (past UNC postdoc) and Tyson Hedrick describe the spatial strategies dragonflies use to chase other fast, agile fliers — in particular, other dragonflies. Previous studies have looked at the paths dragonflies follow when they’re chasing prey (like gnats): while there’s a lot of nuance in what they do, as a simplification we can say that they tend to aim for a point ahead of the prey, so that they intercept it (rather than, for example, flying straight at the prey’s immediate position the entire time). But gnats and other small insects that dragonflies eat aren’t particularly talented fliers. They tend to bumble along and have none of a dragonfly’s speed and agility. The dragonflies don’t have to work very hard to catch them. Lohmann and colleagues were interested in seeing what spatial strategies dragonflies use to chase other fast, agile fliers. To do this, they filmed male dragonflies chasing rival male dragonflies out of their territories. They found that when territorial dragonflies chase invading dragonflies, they follow the same underlying math of the interception pursuit they use to catch prey. However, by making one change – turning a little faster to correct deviations from an efficient interception course – they instead achieve an aggressive, oscillating pursuit path that may serve to show off their flight ability, intimidate the invader, and herd the invader from the territory, all while avoiding the injury that might come from actually colliding with the invader. This finding demonstrates the behavioral precision required for successful pursuit, and it also gives an interesting example of a tiny change in underlying behavior resulting in a major change in observed, functional behavior.

Read the full news story at https://jeb.biologists.org/content/222/11/jeb207126?etoc.
Read the original scientific publication at https://jeb.biologists.org/content/222/11/jeb190884.

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