A reappraisal of insect flight towards a distant point source of wind-borne odor

Abstract

This communication reappraises the behavioral evidence concerning insect flight toward a point source of wind-borne odor in the light of meteorological information not yet considered in this context. The horizontal tracks of puffs of smoke from a generator in the open air were videorecorded and found to continue along nearly straight lines from the source for at least 25 m, while the shifting wind direction caused the plume formed by the succession of puffs to "snake" to and fro. It is inferred from this and much previous work that within such a distance the wind will be aligned on the source of any wind-borne odor wherever the odor can be detected. This being so, a strategy of finding the odor source by flying roughly upwind on meeting the odor, but holding station against the wind with or without casting across it on losing the odor (odor-modulated anemotaxis), seems likely to be highly adaptive, whereas a strategy of flying along the plume ("odor-trail following") seems unlikely since it would often take the flier in "wrong" directions and would be more disrupted by turbulence.

Host-Tree Chemistry Affecting Colonization in Bark Beetles

“…The optomotor anemotaxis mechanism for orientating to pheromone sources proposed for insects, especially moths (David et al, 1982;Baker, 1989), also appears to function in bark beetles (Choudhury and Kennedy, 1980). In this theory, a bark beetle attempts to fly directly upwind when in contact with a packet of pheromone-laden air of the plume, but casts (flies from side to side with respect to the source) when contact is lost.…”

Variable wind directions and anemotactic strategies of searching for an odour plume

“…The latter condition may seem not to be fulfilled, because variation in wind direction causes the odour plume to meander and 'snake' (David et al 1982). However it has been established by atmospheric physicists (Pasquill 1974 is carried away from the source in a relatively straight line for a considerable distance while the plume as a whole may be snaking to and fro across wind.…”

“…However it has been established by atmospheric physicists (Pasquill 1974 is carried away from the source in a relatively straight line for a considerable distance while the plume as a whole may be snaking to and fro across wind. The snake is not the path of the wind: the plume snakes simply because the wind direction varies (Murlis and Jones 1981 ;David et al 1982).…”

From where are insects recruited? A new model to interpret catches of attractive traps

“…This effect increased with distance to the traps (O È strand et al, 2001). As the plantation in the present study was quite dense, it seems reasonable that more males were recaptured at increasing wind speeds because, at weaker wind speeds, the pheromone plume trajectories are less likely to be aligned with wind direction (David et al, 1982), especially in a forest (Elkinton et al, 1987).…”