Attraction and electrophysiological response of Bactrocera jarvisi adults to conspecific volatile emissions from rectal glands

Bactrocera jarvisi (Diptera: Tephritidae) is a moderate insect pest distributed across northern Australia and recorded from wild and commercial hosts. Fruit flies commonly use pheromones to attract mates, and sex pheromones have been extensively studied for some species. However, little is known about the volatiles emitted by B. jarvisi. In this study, we evaluated the attraction of virgin males and females to rectal gland volatiles of same and opposite sex conspecifics in a Y-tube olfactometer. Also, by using a combined gas chromatographic-electroantennographic detection (GC-EAD/EPD) we evaluated the response of antennae (EAD) and maxillary palps (EPD) of males and females to the rectal gland volatiles of same and the opposite sex. Behavioural bioassays showed that males were significantly more attracted to females’ rectal gland than to the control, whereas females did not show any preference for males’ rectal gland over the control. Neither males nor females showed any preference for the rectal gland volatiles of same sex conspecifics over the control. GC-EAD results showed that three volatile compounds present in females’ rectal gland elicited repeatable antennal responses from females and males. Rectal gland volatiles of males did not elicit an antennal response in either females or males. Maxillary palps of B. jarvisi adults were not found to be electrophysiologically responsive to the volatile compounds present in the rectal glands of either sex. Our findings suggest that, unlike most fruit fly species, in which males produce sex pheromones to attract females, in B. jarvisi females release volatiles to attract males.