Spermatophore weight and sperm number in the southernmost species of the genus Poecilimon Fischer, 1853 (Orthoptera: Phaneropterinae)

Abstract

Male bushcrickets transfer during copulation edible spermatophores that are consumed by bushcricket females as nutrient sources. They consist of two edible parts; the smaller ampulla that contains the ejaculate and the larger spermatophylax. Both components of the spermatophore and the number of sperm transferred vary greatly in size respectively number between species. This paper examines the relationship between body size and spermatophore components, including sperm number in Poecilimon (Poecilimon) syriacus Brunner von Wattenwyl, 1891 which is known from the southernmost area of the genus distribution. Water content of spermatophylax was found to be about 90% of wet mass. Consistent with many previous studies, the spermatophore components, including dry spermatophylax weight, were positively affected by male body weight, but there was no relationship between body weight and sperm number. A positive relationship between wet spermatophylax weight and ampulla weight supports the ejaculate protection hypothesis. The results of this study suggest that P. syriacus makes a large investment in spermatophylax and ampulla relative to its body size in comparison to other species of the genus Poecilimon.