Pheromone dialects in European turnip moths Agrotis segetum

Female pheromone gland extracts from cultures of Agrotis segetum (Schiff.), originating from Sweden, France, Hungary and England were analysed for pheromone components and precursors (fatty acids). The pheromone blends were similar in the moths from the Swedish, English and Hungarian populations, whereas the French diverged with a much higher amount of (Z)-5-decenyl acetate relative to the homologous pheromone components (Z)-7-dodecenyl acetate and (Z)-9-tetradecenyl acetate. The frequency of receptor cells sensitive to (Z)-5-decenyl acetate on male antennae, was also highest in the French insects. In correspondence with the earlier reported behavioural significance of (Z)-5-decenyl acetate in the French turnip moth, this is indicative of a French pheromone dialect. The biosynthetic basis for the shift in pheromone production as well as ecological and evolutionary implications of the findings are discussed