Measuring Behavior 2005: Braks et al.

3-D flight track analysis of mosquito orientation to oviposition cues

M.A.H. Braks, J. Bau and R.T. Cardé

Department of Entomology, University of California, Riverside, CA, USA

Female mosquitoes use a combination of sensory modalities to find and determine the suitability of oviposition sites. Wind-borne odorants appear to be particularly important in this process. The odors promoting egg laying have been classified as attractants, arrestants, and stimulants, whereas those that inhibit egg laying have been termed deterrents and repellents. A number of potential semiochemicals for Culex species are already known, including the ‘egg raft pheromone’ as well as compounds identified from the headspace above water from suitable oviposition sites. The chemical ecology studies for identifying these semiochemicals have largely depended on bioassays measuring endpoint behaviors, that is, did a given odor increase or decrease the number of eggs deposited. As a consequence, limited information is available on the role of these or the identity of other semiochemicals involved in the orientation of mosquitoes to a suitable oviposition site. Such information is essential for the improvement of gravid traps commonly used in arboviral surveillance and control programs.

To examine orientation maneuvers of mosquitoes, 3-D video recording and analysis systems were developed. Individual mosquitoes were released downwind of a turbulent odor plume and their behavior was recorded with two video cameras, one from the side and one from the bottom of the 1.5 m wind tunnel. The two camera views were synchronized with an Event & Video Control Unit (Peak Performances Technologies Inc.), overlaid and recorded on one videotape. Each flight track was digitized and its 3-D flight coordinates were obtained with Motus (Peak Performances Technologies Inc.) at 30 Hz and the relevant flight parameters were calculated. Custom-made programs in Visual Basic® were employed to analyze the flight tracks.

Paper presented at Measuring Behavior 2005 , 5^th International Conference on Methods and Techniques in Behavioral Research, 30 August - 2 September 2005, Wageningen, The Netherlands.