Response of Bactrocera fruit flies (Diptera: Tephritidae) to phytochemical lures: evolutionary and functional significance

Bactrocera is a speciose genus of tephritid fruit fly that includes internationally important pests of fruit and vegetables. Monitoring and control of these pestiferous species largely dependent on male attractants or lures: the most common male lures are methyl eugenol or raspberry ketone (its synthetic analogue cue lure). Males show strong and positive olfactory and gustatory response to one of these plant-derived chemicals thus used in management through a lure-and-kill approach. Despite their applied importance however, the evolutionary and functional significance of lures in the natural history of Bactrocera flies remain enigmatic. Males that have imbibed the lures commonly have a mating advantage over unfed males, presumably by releasing more attractive pheromone volatiles and subsequent selection by females for copulation. Female benefits for the selection of lure-fed males is unclear with studies concentrating on direct female effects evidence no such benefits. Hence, it has been postulated that the strong lure response is a case of runaway selection, where males receive direct benefits and females receive indirect benefits via ‘sexy sons’.