Bees and flies: Synergistic effects on female plant fitness in Delphinium barbeyi (Ranunculaceae)

Most flowering plant species rely on animal visitors to transfer pollen and maximize seed production.  In turn, pollinators need plants to supply nectar and pollen food resources.  After pollination, other animals reap the benefits of this interaction by consuming the developing or mature seeds.  The mix of single and synergistic effects that animal consumers have on their plant resources requires that plants simultaneously mediate the behavior of mutualistic and antagonistic animal visitors.  For example, how do plants maximize pollination and subsequent seed production, while minimizing seed predation?  This study examined the relationships among floral traits (nectar spur length, flowering phenology, and flower production), pollen receipt, and seed production in Delphinium barbeyi (Ranunculaceae).  We also experimentally tested how the presence or absence of bee pollinators affected pre-dispersal fly seed predation (oviposition, larval survival, and seed consumption).  We found that floral traits influenced pollination and also affected seed predation, which dampened the overall relationship between pollination and plant fitness.  Our results demonstrate how understanding the behavioral responses of multiple animal consumers to dynamic floral resources can help explain the diversity of effects that animals have on plant fitness.