Aggressive Behavior and Territoriality in the Olive Fruit Fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae): Role of Residence and Time of Day

Bactrocera oleae is a worldwide olive fruit pest. In late afternoon males form swarms on the windward side of trees. Within the swarm, each male occupies a leaf and aggressively excludes male conspecifics before starting courtship displays. Females display aggressive interactions each other too, particularly when they are in close proximity of oviposition sites. In this research, the aggressive behavior displayed by both sexes was quantified. Aggressions were composed by wing waving, fast running towards the opponent, pouncing and boxing on the head and thorax of the foe. High-speed videos highlighted that the parameters characterizing the aggressions did not strongly differ between sexes and between residents and intruders. Resident flies won more combats, both in male-male and female-female aggressive interactions. In both sexes, aggressions were more frequent in the late morning than in the afternoon. Among males, aggressions could be functional to maintain single leaf territories in which each fly can perform courtship displays. Through aggressions females could gain and maintain single oviposition sites. Lastly, by favorable fight outcomes B. oleae could also get access to food sources on olive leaves and fruits.