title: Ejaculate economics: an experimental test in a moth.
abstract: Increasing evidence shows that spermatogenesis is costly. As a consequence, males should optimize the use of their sperm to maximize their reproductive outputs in their lifetime. However, experimental evidence on this prediction is largely lacking. Here, we examine how a male moth Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) responds to the presence of rivals or additional mates and how such response influences his lifetime reproductive fitness. We show that when rival males are present around a copulating pair, the male ejaculates more sperm to win a sperm competition battle but in such an environment he inseminates fewer females, sires fewer offspring and lives shorter. The opposite is the case when additional females are present during copulation. These findings reveal that elevated reproductive expenditure owing to sperm competition intensity is made at the expense of longevity and future reproduction.
authors.affiliation: Laboratory of Biological Invasion and Ecosecurity, Yunnan University, , Kunming 650091, People's Republic of China.
authors.forename: Jin
authors.initials: J
authors.lastname: Xu
authors.forename: Qiao
authors.initials: Q
authors.lastname: Wang
mesh_terms: D000818:Animals; D004542:Ejaculation; D008297:Male; D009036:Moths / Q000502:physiology*; D012726:Sexual Behavior, Animal; D013094:Spermatozoa / Q000502:physiology*
keywords: Ephestia kuehniella; male lifetime reproductive fitness; sperm allocation; sperm competition intensity