Close-distance courtship of laboratory reared Bactrocera tryoni (Diptera: Tephritidae)

Abstract

Close-range courtship behaviours are a critical element of a species' biology but, if rapid, can often be overlooked. Beyond male chemical and audio calling, close-range courtship interactions leading to copulation in the Queensland fruit fly Bactrocera tryoni are unknown; this may be due to a true absence or because they have been overlooked and not previously investigated. We sought to resolve the close-range courtship sequence of B. tryoni and construct an ethogram of identified behaviours. Close-range video recordings of B. tryoni courtship were taken during the dusk mating window and an ethogram constructed by combining all observed behaviours which led to successful copulation and unsuccessful copulation. While the previously well-recognised male wing fanning behaviour was documented, a number of other behaviours were identified for the first time in B. tryoni courtship, including female ovipositor extension, and both male and female synchronous supination, face-to-face contact, and fore- and hind leg interactions. Analyses showed that the total duration of male synchronous supination, but not the number of occurrences, differed significantly between successful and unsuccessful males. Male foreleg interaction with the female abdomen was significantly different in both total duration and total number of occurrences between successful and unsuccessful males. The results reinforce data obtained from other Bactrocera species of simplified courtship sequences in these flies in comparison with other tephritid genera, but nevertheless courtship is more complex than previously recognised.