Aggregation pheromone released from the palps of feeding female Phlebotomus papatasi (Psychodidae)

Experiments with 2 feeding chambers: 1 new, the other having been used previously for feeding, showed that an aggregation and feeding pheromone had been secreted onto the chamber membranes by engorging females. Of the different extracts from parts of females or males tested, only the female palps and mouth parts exhibited pheromonal activity. The reaction to the pheromone was shown to be olfactory, and the pheromone itself is volatile. Reaction to the pheromone was dependent on chamber temperature. Pheromone-baited chambers at 28°C elicited a high response and the specific reaction to the pheromone was eliminated at 36°C. Large vacuolated cells in the 3rd and 4th segments and in Newstead's organ in the palps of females are suggested as a source of the pheromone.