WILLIS, M.A.: Odor-modulated navigation in flying insects

Many organisms, ranging from bacteria, through nematodes, to insects, fish and mammals, use air- or water-borne plumes of odor molecules to locate distant unseen resources. Remarkably, the movement tracks that many species produce when tracking odors have a very similar side-to-side zigzag shape. While this similarity does not necessarily indicate similar underlying mechanisms, it does suggest that there may be something fundamentally �good’ about this approach to tracking chemical plumes. The pheromone-modulated flight of male moths searching for receptive females is amongst the best known system to study olfactory navigation. The biological model we study is the moth Manduca sexta, in which both males and females use air-borne odor plumes to locate critical resources from long distances. Tracking an odor plume through a complex and changing environment is arguably the most challenging behavior that these animals perform, in part because they do so while flying. This requires the individuals to generate stable locomotion in a fluid medium, and then, using visual, mechanosensory and olfactory information, determine the wind speed and direction, their own speed and steering and, most importantly, maneuver to maintain contact with the wind-borne odor. Olfactory orientation in moths is a particularly good system to study the mechanisms underlying this behavior because it has been studied across a broad-range of organizational levels: from single neuron responses to different odorants to using computer simulation and robotic approaches to understand control algorithms underlying plume tracking behavior. Our recent results span many of these organizational levels and add to our current understanding of odor-guided orientation. Supported by: DARPA contract #N66001-98-C-8628 and ONR/DARPA grant #N00014-98-1-0823.