Mating has No Effect on Male Longevity in the MothAmorbia cuneana(Tortricidae)

Abstract

In some insects, males invest heavily in each mating thus reducing the typical sexual imbalance in potential reproductive rates which, in turn, influences the mode and intensity of sexual selection. In Lepidoptera, males invest in mate searching, courtship, ejaculate production and, in some species, in genital spines shed inside the female. Despite this substantial investment, evidence regarding its effect on male survival is contradictory. The effect of successful mating (i.e. copulations resulting in transfer of an ejaculate and deciduous genital spines) on male longevity was experimentally estimated in the moth Amorbia cuneana (Tortricidae), a pest of avocado. Our results do not support the prediction that mating costs result in a reduction in male longevity: virgin (n = 16) and mated (n = 26) males lived a similar number of days. It is hypothesized that reduced mating opportunities have selected for virgin males that are always ready to transfer large ejaculates and thus against the diversion of resources from reproductive tissues to somatic maintenance in unmated males.