Evaluating female remating rates in light of spermatophore degradation in Heliconius butterflies: pupal-mating monandry versus adult-mating polyandry

1) Butterflies are frequently used in comparative studies of sexual selection because of their diverse mating systems. In Heliconius, the two major clades in the genus are characterized by contrasting pupal-mating and adult-mating strategies. Adult-mating females are considered to be promiscuous while pupal-mating females are thought to be monandrous. 2) Counting spermatophores in female Lepidoptera is a common method for assessing patterns of female remating. However, in pupal-mating Heliconius butterflies spermatophores can become completely degraded leading to a potential underestimation of female remating rates. 3) We qualitatively characterized the different states of spermatophore degradation, and showed that complete degradation takes approximately three weeks in captive-bred H. erato females. 4) We counted spermatophores and/or assayed spermatophore degradation in >500 Heliconius females across 28 species sampled from natural populations. Among pupal-maters these observations...