Observations on the mating behavior of the alfalfa blotch leafminer, Agromyza frontella (Rondani) (Diptera: Agromyzidae), and evidence of a female sex pheromone.
The mating behaviour of Agromyza frontella was studied in the laboratory at 20°C, 60% RH and LD 14:10. Adults mated on the day of emergence, with no periodicity during the photophase. The host plant, lucerne, was essential for mating to occur, its presence affecting female receptivity rather than male copulatory behaviour. Males tended to enter a stationary phase once they were near a female, before undertaking a final approach. This resulted in male aggregations around females, and under such conditions males exhibited a characteristic wing vibrating behaviour. The latter was considered to be mainly a male-male signal. The majority of females which mated exhibited ovipositor pumping behaviour that stimulated male approach, but this behaviour was not essential to attract males. The presence of a cuticular sex pheromone is suggested. Hexane extracts of whole virgin females applied to male cadavers increased the time males spent on the plant, the number of contacts with treated cadavers, the incidence of attempted copulations and wing vibrating behaviour compared to untreated male cadavers. It is concluded that females control copulation in A. frontella and both semiochemical and visual cues are important in eliciting male mating behaviour.