Copula duration and sperm economy in the large thistle aphid, Uroleucon cirsii (Hemiptera: Aphididae)

Abstract

Experiments on copula duration indicate that the nature of mate competition and sperm storage in the large thistle aphid, Uroleucon cirsii (L.), differs from that in the well-studied yellow dung fly, Scatophaga stercoraria (L.). Unlike the situation in the dung fly, second copulas are shorter on average than first copulas for both individual males and females. This suggests that male aphids have a limited amount of sperm at their disposal and that the females capacity to store sperm is limited as could be expected when males were not able to displace sperm from former copulas.