Mating Behavior and Spermatophore Characteristics in Two Closely Related Bushcricket Species of the Genus Phonochorion (Orthoptera: Phaneropterinae)

Abstract

Bushcrickets comprise an important group of model organisms, which are intensively studied to understand the evolution of mating behavior. During the mating process, the male bushcricket transfers a costly and edible spermatophore consisting of two parts to the female. This unique behavior makes bushcricket species appropriate study organisms for investigating spermatophore size variations across entire bushcricket family (Tettigoniidae). The functions of the spermatophylax and the ampulla, which constitute the spermatophore, have been addressed in many studies. Although the costs and benefits of mating for male and female bushcrickets may vary depending on species, there are some common evolutionary traits. In the present study, mating behaviors and spermatophore characteristics of two endemic bushcricket species, Phonochorion uvarovi and P. artvinensis, distributed at the high altitudes of the Ka double dagger kar Mountains, northeastern Turkey, were examined. The data on two closely related species belonging to the genus of Phonochorion show that they have different reproductive investments in terms of spermatophore and sperm numbers in spite of similar habitat and nutritional preferences. P. artvinensis had a larger spermatophore, spermatophylax and ampulla, but transferred fewer sperm. Male age and weight had a significant effect on spermatophore, spermatophylax and ampulla investments in P. uvarovi while only male weight was a significant factor in P. artvinensis. A positive relationship between the spermatophylax and the ampulla weights in both species supports the ejaculate protection hypothesis in the Phonochorion species. Even though further studies on Phonochorion should be conducted to provide a more clear comparison with other groups in the barbitistine, this study demonstrates that both P. uvarovi and P. artvinensis make little spermatophore investment relative to their body size in comparison to other barbitistines.