Meeting Abstract
Long-legged flies of the genus Condylostylus (Diptera: Dolichopodidae) are small-sized (~5mm) aerial predators, commonly found in gardens and edges of forests in tropical areas. They keep their legs extended during flight and use them for steering and grabbing their prey. This high maneuverability is further enhanced by their extremely short times of reaction to a visual stimulus. As a result, predatory pursuits in these species are different from those reported previously for other flies and dragonflies. Using high-speed videography and 3D flight pattern reconstruction, we analyzed pursuit flight in Condylostylus spp. The flies were filmed while chasing targets moving in different patterns. We found that during a pursuit, the flies approached their target steadily via reactive navigation. Reactive maneuvering during a pursuit happened within 7-10ms of the target’s steering. We also found that targets moving within 20 cm are usually approached and followed by the flies. Final approach and capture of the target happened only within 6cm of it and in response to target’s evasive maneuvers. In contrast, targets that continued moving in a straight line were observed from that distance until the fly retreated. We discuss this pursuit strategy as a consequence of the specialization of this group of flies in hunting small, fast maneuvering, and swarming insects. Such a strategy where the interest of the predator is maintained by the evasive maneuvering if its target, has never been described before in flies and offers an excellent ground for comparison with aerial predators whose success is based on speed instead of maneuverability.
