Visual approach computation in feeding hoverflies
Abstract
On warm sunny days female hoverflies are often observed feeding from a wide range of wild and cultivated flowers. In doing so, hoverflies serve a vital role as alternative pollinators, and suggested to be the most important after bees and bumblebees. Unless the flower hoverflies are feeding from is large, they do not readily share the space with other insects, but instead opt to leave. We have used high-speed videography followed by 3D reconstruction of flight trajectories to quantify how female Eristalis hoverflies respond to approaching bees, wasps and two different hoverfly species. We found that in 94% of the interactions the occupant female left the flower when approached by another insect. We found that compared to spontaneous take-offs, the occupant hoverfly's escape response was performed at ∼3 times higher speed (spontaneous take-off at 0.2±0.05 m/s compared with 0.55±0.08 m/s when approached by another Eristalis). The hoverflies tended to take off upward and forward, while taking the incomer's approach angle into account. Intriguingly, we found when approached by wasps that the occupant Eristalis took off at a higher speed and when the wasp was further away. This suggests that feeding hoverflies may be able to distinguish these predators, demanding impressive visual capabilities. Our results, including quantification of the visual information available before occupant take-off, provide important insight into how freely behaving hoverflies perform escape responses from competitors and predators (e.g. wasps) in the wild.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jan 01, 2018
- Source ID
- 10.1242/jeb.177162
Entities
People
- Karin Nordström
- Malin Thyselius
- Paloma T Gonzalez-Bellido
- Trevor J Wardill
Organizations
- Air Force Office of Scientific Research
- Australian Research Council
- Biotechnology and Biological Sciences Research Council
- Flinders University
- Signhild Engkvists Stiftelse
- Stiftelsen Längmanska Kulturfonden
- University of Cambridge
- Uppsala University