title: A Novel Interception Strategy in a Miniature Robber Fly with Extreme Visual Acuity.
abstract: Our visual system allows us to rapidly identify and intercept a moving object. When this object is far away, we base the trajectory on the target's location relative to an external frame of reference [1]. This process forms the basis for the constant bearing angle (CBA) model, a reactive strategy that ensures interception since the bearing angle, formed between the line joining pursuer and target (called the range vector) and an external reference line, is held constant [2-4]. The CBA model may be a fundamental and widespread strategy, as it is also known to explain the interception trajectories of bats and fish [5, 6]. Here, we show that the aerial attack of the tiny robber fly Holcocephala fusca is consistent with the CBA model. In addition, Holcocephala fusca displays a novel proactive strategy, termed "lock-on" phase, embedded with the later part of the flight. We found the object detection threshold for this species to be 0.13°, enabled by an extremely specialized, forward pointing fovea (∼5 ommatidia wide, interommatidial angle Δφ = 0.28°, photoreceptor acceptance angle Δρ = 0.27°). This study furthers our understanding of the accurate performance that a miniature brain can achieve in highly demanding sensorimotor tasks and suggests the presence of equivalent mechanisms for target interception across a wide range of taxa. VIDEO ABSTRACT.
authors.affiliation: Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB3 2EG, UK; Eugene Bell Center for Regenerative Biology and Tissue Engineering, MBL, 7 MBL Street, Woods Hole, MA 02543, USA. Electronic address: tjw79@cam.ac.uk.
authors.forename: Trevor J
authors.initials: TJ
authors.lastname: Wardill
authors.affiliation: Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB3 2EG, UK.
authors.forename: Samuel T
authors.initials: ST
authors.lastname: Fabian
authors.affiliation: Leader Heights Animal Hospital, 199 Leaders Heights Road, York, PA 17402, USA.
authors.forename: Ann C
authors.initials: AC
authors.lastname: Pettigrew
authors.affiliation: Computational Physics, Zernike Institute for Advanced Materials, University of Groningen, Groningen 9747 AG, the Netherlands.
authors.forename: Doekele G
authors.initials: DG
authors.lastname: Stavenga
authors.affiliation: Centre for Neuroscience, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia.
authors.forename: Karin
authors.initials: K
authors.lastname: Nordström
authors.affiliation: Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB3 2EG, UK; Eugene Bell Center for Regenerative Biology and Tissue Engineering, MBL, 7 MBL Street, Woods Hole, MA 02543, USA. Electronic address: ptg25@cam.ac.uk.
authors.forename: Paloma T
authors.initials: PT
authors.lastname: Gonzalez-Bellido
mesh_terms: D000818:Animals; D004175:Diptera / Q000502:physiology*; D009039:Motion Perception; D011597:Psychomotor Performance; D014792:Visual Acuity
keywords: flight; interception strategy; invertebrate; moving target; predation; retina; spatial resolution; tracking; vision