The worldwide importance of honey bees as pollinators in natural habitats

<jats:p>The western honey bee (<jats:italic>Apis mellifera</jats:italic>) is the most frequent floral visitor of crops worldwide, but quantitative knowledge of its role as a pollinator outside of managed habitats is largely lacking. Here we use a global dataset of 80 published plant–pollinator interaction networks as well as pollinator effectiveness measures from 34 plant species to assess the importance of<jats:italic>A. mellifera</jats:italic>in natural habitats.<jats:italic>Apis mellifera</jats:italic>is the most frequent floral visitor in natural habitats worldwide, averaging 13% of floral visits across all networks (range 0–85%), with 5% of plant species recorded as being exclusively visited by<jats:italic>A. mellifera</jats:italic>. For 33% of the networks and 49% of plant species, however,<jats:italic>A. mellifera</jats:italic>visitation was never observed, illustrating that many flowering plant taxa and assemblages remain dependent on non-<jats:italic>A. mellifera</jats:italic>visitors for pollination.<jats:italic>Apis mellifera</jats:italic>visitation was higher in warmer, less variable climates and on mainland rather than island sites, but did not differ between its native and introduced ranges. With respect to single-visit pollination effectiveness,<jats:italic>A. mellifera</jats:italic>did not differ from the average non-<jats:italic>A. mellifera</jats:italic>floral visitor, though it was generally less effective than the most effective non-<jats:italic>A. mellifera</jats:italic>visitor. Our results argue for a deeper understanding of how<jats:italic>A. mellifera</jats:italic>, and potential future changes in its range and abundance, shape the ecology, evolution, and conservation of plants, pollinators, and their interactions in natural habitats.</jats:p>