Pre-winter copulation enhances overwintering success of Orius females (Heteroptera: Anthocoridae)

The majority of insects that overwinter in the adult stage copulate post-winter. Some such insects copulate not only post-winter, but also pre-winter and/or during winter. In Orius species, only females overwinter. As they have no chance to copulate post-winter, they do so pre-winter. We expected pre-winter copulation to be associated with increased survival of females during overwintering; therefore, we tested the effects of pre-winter copulation on winter survival in females of three Orius species, O. sauteri, O. nagaii and O. strigicollis. Under semi-field conditions, clear differences in overwintering survival were observed between copulated and virgin females in the late overwintering period. Overwintering success of copulated females was higher than that of virgin females; however, copulation frequency did not affect winter survival of females. With regard to the mechanism increasing winter survival, two possible explanations arose from this study. The first is the donation of nutrients from males through copulation, and the second is that copulation affects diapause syndrome and/or behavioral changes in females.