Mating behavior and female receptivity in a <scp>Japanese</scp> mason bee <i>Osmia taurus</i> ( <scp>Hymenoptera: Megachilidae</scp> )

Abstract The genus Osmia is a promising model for studying sexual selection due to its elaborate mating behavior. However, detailed investigations of mating behavior in Japanese Osmia species remain limited. This study describes the mating behavior of the Japanese mason bee Osmia taurus and examines female receptivity under different conditions to provide foundational data for future research. Mating in O. taurus consisted of three distinct phases: precopulatory (mean ± SD = 277.4 ± 289.3 s), copulatory (17.5 ± 4.4 s) and post‐copulatory (3,501.8 ± 1,606.7 s), with a notably prolonged post‐copulatory phase. Female receptivity declined with age; over 60% of 0‐day‐old virgin females mated, whereas no mating occurred in 2–3‐day‐old virgins. Additionally, females lost receptivity immediately after a single mating and did not regain it even after 7–9 days, strongly suggesting monandry. The results also indicate a rapid decline in female attractiveness after mating, suggesting changes in pheromonal communication. These findings highlight the importance of using newly emerged females in mating experiments and raise intriguing questions about the evolutionary and physiological mechanisms underlying the rapid loss of female receptivity in this species.