Mating Behaviour of the Queensland Fruit Fly, Dacustryoni (Diptera: Tephritidae), in Field Cages

The behaviour leading to mating in Dacus tryoni was studied in a field cage containing a peach tree. The behaviour in the field cage was similar to that which has been observed in nature. Under natural lighting conditions mating was entirely limited to a period of about half an hour as the light intensity fell at dusk, sexual activity beginning about 10 min before the official sunset time. All males in the cage aggregated into a loose flying swarm which soon settled on the windward side of the tree. Within the settled swarm each male defended a small area on a leaf where he stridulated and released pheromone. Females flew into the aggregation singly. Each female landed near a male and then walked up beside him. The male's behaviour did not change until the female entered his visual field. Then mounting occurred immediately and stable copulation was achieved within a few seconds. The relationship of the aggregation to the aerial swarming habit of many Diptera is discussed.