Finding of a sex pheromone source by gypsy moths released in the field

Abstract

“Moths display some of the most striking examples of long-distance chemical communication in the animal kingdom”¹. Recent theories of how the male moths find a distant female have invoked steering by two different directional cues: (1) gradients of odour concentration in the air, used in ‘aerial odour-trail following’, and (2) the wind, used in ‘odour-modulated anemotaxis’^2–7. Laboratory evidence has favoured the latter theory as well as contradicting the earlier radiation theories^8–11, but the issue could not be settled without recording in the field the flight track of a male moth and, simultaneously, the track of the odour plume. This has now been done with gypsy moths and wind-borne bubbles, confirming theory (2) and showing in addition that cross-wind casting itself contributes to a moth's progressive approach to the odour source, an unexpected consequence of the way odours are dispersed by the wind¹².