Defense of Oviposition Sites by Female Oriental Fruit Flies (Diptera: Tephritidae)

Abstract

Field observations revealed that females of the oriental fruit fly, Bactrocera dorsalis (Hendel), defended oviposition sites on mangos (Mangifera indica L.) against conspecific females. In most encounters, females simply lunged at opponents and chased them off the fruit without physical contact. However, head-butting and pushing were observed in about 10% of the contests. Body size was a key determinant of fighting success, with larger females winning 85% of the encounters. In a field experiment, arrivals, oviposition, and aggression of females were compared between intact vs. sliced peaches. Similar numbers of females landed on the two classes of fruits, but a greater proportion of alighting females oviposited on sliced peaches than intact peaches. The adaptive function of female territoriality is discussed in light of these findings.