Ejaculate allocation and female remating in a tropical tephritid fruit fly

Abstract

Males that copulate repeatedly may suffer from reduced sperm stores. However, few studies have addressed sperm depletion from both female and male perspectives. Here, we show that male Anastrepha obliqua (Diptera: Tephritidae) do not ejaculate all available sperm and are left with mature sperm in the seminal vesicles even after copulating as often as three times in half a day. Ejaculate size was not related to male mating history, time elapsed since mating, copulation duration, female thorax length or head width. a repeatability analysis revealed that males were consistent in the amount of sperm they allocated to virgin females. This suggests that males cannot deliver consistent amounts of accessory gland products (AGPs), which are transferred in the ejaculate together with sperm. AGPs are known to inhibit female remating in other insects. results suggest that males strategically allocate similar numbers of sperm among successive mats without exhausting sperm reserves for future encounters, but may suffer from AGP depletion. We discuss the role that differential sperm storage and excess sperm may have in mediating sperm competition and tie our results to the unique natural history of A. obliqua.1 page(s