Why do florivores prefer hermaphrodites over females in Nemophila menziesii (Boraginaceae)?

Abstract

Although florivores can destroy significant amounts of sexual tissues and indirectly affect pollination, little is known about their preferences, which could shape the evolution of floral traits or defense. In this study, we used a gynodioecious plant Nemophila menziesii, and its main florivore Platyprepia virginalis, to test which floral characteristics are associated with florivory in the field and with florivore choice in the laboratory. Hermaphrodite flowers consistently received more damage than nearby females in the field. In the laboratory setting, florivores also preferred unmanipulated hermaphrodites versus unmanipulated females. Systematic evaluation of hermaphrodite traits, such as corolla size, anther presence, and corolla color, revealed that corolla diameter was the main determinant of florivore preference in this system. Here, we discuss the implications of both pollinator and florivore choice in the evolution of corolla size and sex ratio in gynodioecious species with cytoplasmic male sterility and emphasize the need for more information on the preferences of florivores.