Co-flowering neighbor alters pollinator composition and influences reproductive success in a plant pollinated by multiple insects

The effect of the interactions among co-flowering plants for pollination has always been explained by changes in pollinator visiting frequency and/or foraging behavior. For most flowering plants with generalized pollination system, little is known about the influence of co-flowering neighbor on pollinator composition and its ecological consequences. Mazus miquelii , a plant with sensitively bilobed stigma, and its two naturally common co-flowering plants, Glechoma longituba and Ajuga decumbens were used to set the study system. We investigated pollinators’ visiting frequency and behavior, visiting frequency and relative composition of each pollinator type as well as seed production. Our results indicated that plant reproductive success significantly differed with co-flowering plants. However, neither pollinators’ visiting frequency nor foraging behavior could be attributed to the influence of co-flowering neighbor on reproductive success of M. miquelii . Flowers of M. miquelii were pollinated by more individuals of Osmia sp. when co-occurring with A. decumbens , while Halictus sp. was the main pollinator of M. miquelii when it was co-flowering with G. longituba . Comparatively, insects of Osmia sp. had higher effectiveness of pollen transfer than those of Halictus sp. The stigmatic pollen load of M. miquelii was higher co-flowering with A. decumbens than with G. longituba . The co-flowering neighbor significantly altered the pollinator composition and influenced pollen transfer efficiency, which might definitely be responsible for the changes in the focal plant reproductive success. This study improved our understanding on pollinator-mediated plant–plant interactions, particularly the uncertain effects of co-flowering plants on a focal plant from different communities.