Importance of Chemical Stimuli in Precopulatory Behaviour of Blackflies Simulium Lineatum Mg. (Diptera: Simuliidae)

Abstract

The importance of chemical stimuli in mate recognition by blackflies Simulium lineatum (Meigen 1984) was analysed. The blocking of male chemoreceptors either by cutting off antennae or treating them with ZnSO₄ had no effect on a male’s approach to a female. However, a female’s dummy was touched significantly more frequently by intact males compared to those with blocked chemoreceptors (i.e. 65% of intact vs. 44% of antennaeless males; 73% of intact males vs. 42% of those treated with ZnSO₄). Attempts of males with blocked chemoreceptors to copulate decreased significantly compared to those of intact ones (i.e. by 35% after antennaectomy and by 45% after treatment with zinc sulphate). Results indicate that in S. lineatum, chemical stimuli are involved in mate recognition, i.e. in this species sex pheromones are present and act at a very close distance. Inhibition of chemoreceptors had no drastic effect on survival of males within an 18-hour period. Some changes in locomotory activity of S. lineatum males indicate that there was no direct influence on precopulatory behaviour.

Keywords:

• Inhibition of chemoreceptors
• female dummy
• sex pheromone
• pheromonal communication