Meeting Abstract
Male moths locate females by navigating along a plume of her pheromone, often flying 100s of meters en route. As the first male to find a calling female is apt to be her mate, this can be termed “a race to find the female” and it is assumed to be under strong selective pressure for efficiency and rapidity. Locating a distant, odor-linked resource involves two strategies. First, contact the outer envelope of the odor plume. When wind direction is relatively invariant, the plume stretches out and then a strategy may favor crosswind flights, although upwind and downwind paths may be optimal when wind direction shifts over 60 degrees. Alternatively, the path may be random with respect to the direction of wind flow, with periodic changes in direction as in a Lévy Walk or a Random Walk. After first odor detection, a second strategy follows where moths navigate along the plume by heading upwind when odor is detected with crosswind casting to re-establish contact if the plume is lost. These mechanisms are well established from wind-tunnel manipulations. This orientation path is not straightforward in nature, because atmospheric turbulence fragments the plume creating large odor gaps. Further, a shifting wind direction can lead the responder out of the plume. One way to explore which strategies are optimal for enabling initial plume contact and subsequent plume tracking is through simulation modeling of plume dispersal and flight strategies. Our simulations suggest that search strategies similar to Lévy Walks are most apt to result in quick plume contact. While a searching trajectory aimed predominately crosswind performed almost as well in certain conditions, downwind trajectories did not prove as successful. These results are in accord with the behavior of moths flying in the field.
