Ovarian dynamics in relation to host quality in the Walnut-infesting Fly, Rhagoletis juglandis

1. Reproductive behaviour is routinely studied with a view towards characterizing how an animal responds to variation in resource abundance and quality. This characterization is less commonly made with respect to reproductive physiology. 2. In the Walnut-infesting Fly, Rhagoletis juglandis, ovarian development is cued by the presence of the host fruit resource. In this study, I examined how ovarian development was affected by two host characteristics that relate to competition in the juvenile stages: fruit size and presence of conspecific larvae. 3. Large fruit promoted egg maturation more than small fruit, and uninfested fruit promoted maturation more than larval-infested fruit. Both effects were reproduced with artificial models of fruit. 4. The functional significance of these effects and ramifications for individual-level dynamics in oviposition behaviour are discussed.