A meta‐analysis of single visit pollination effectiveness comparing honeybees and other floral visitors

Abstract

Premise Many animals provide ecosystem services in the form of pollination including honeybees, which have become globally dominant floral visitors. A rich literature documents considerable variation in single visit pollination effectiveness, but this literature has yet to be extensively synthesized to address whether honeybees are effective pollinators. Methods We conducted a hierarchical meta‐analysis of 168 studies and extracted 1564 single visit effectiveness (SVE) measures for 240 plant species. We paired SVE data with visitation frequency data for 69 of these studies. We used these data to ask three questions: (1) Do honeybees (Apis mellifera) and other floral visitors differ in their SVE? (2) To what extent do plant and pollinator attributes predict differences in SVE between honeybees and other visitors? (3) Is there a correlation between visitation frequency and SVE? Results Honeybees were significantly less effective than the most effective non‐honeybee pollinators but were as effective as the average pollinator. The type of pollinator moderated these effects. Honeybees were less effective compared to the most effective and average bird and bee pollinators but were as effective as other taxa. Visitation frequency and SVE were positively correlated, but this trend was largely driven by data from communities where honeybees were absent. Conclusions Although high visitation frequencies make honeybees important pollinators, they were less effective than the average bee and rarely the most effective pollinator of the plants they visit. As such, honeybees may be imperfect substitutes for the loss of wild pollinators, and safeguarding pollination will benefit from conservation of non‐honeybee taxa.

Honey bee introductions displace native bees and decrease pollination of a native wildflower

“…For example, the generally positive direct effect of honey bee visits may be of greater importance in the absence of competition; in cases where native pollinators have become rare or locally extinct, honey bees often increase pollination (Hanna et al, 2013; Lomov et al, 2010) and can even “rescue” plant populations from reproductive failure in isolated habitat fragments (Dick, 2001). However, negative indirect effects may occur and even outweigh direct effects when honey bees competitively displace native pollinators, especially when honey bees are ineffective substitutes (Page et al, 2021).…”

Why honeybees are poor pollinators of a mass‐flowering plant: Experimental support for the low pollen quality hypothesis

“…Recent meta‐analyses showed that honeybees are generally less efficient when compared to the most efficient non‐ Apis pollinators for various plant species (Hung et al, 2018; Page et al, 2021), and this is particularly true for when honeybees are compared to birds (Page et al, 2021). It also applies both where honeybees are native (e.g., Brown et al, 2009) and where they are introduced (e.g., Celebrezze and Paton, 2004).…”

“…The western honeybee, Apis mellifera L., is native to Europe, Africa, and the Middle East, but due to beekeeping it is now distributed around the world (Han et al, 2012). Honeybees are also the most widely used and economically valuable pollinator of crops in monoculture worldwide (Klein et al, 2007), but there is increasing evidence that they are not particularly effective pollinators in either agricultural or in natural environments (Garibaldi et al, 2014; Hung et al, 2018; Page et al, 2021). Just over 50 years ago, Free (1966a) published an important, but often overlooked, paper that used mark‐recapture data to show that honeybees tend to confine their activities to single apple trees, even during subsequent foraging bouts.…”

Multi-species crop mixtures increase insect biodiversity in an intercropping experiment

“…Previous studies showed that ecosystem service delivery is positively influenced by the richness of serviceproviding organisms like flower visitors (Dainese et al 2019). Although honeybees (mainly the European honeybee Apis mellifera L.) are kept worldwide to provide crop pollination, other insects (such as wild bees, flies, beetles, wasps) contribute a lot more to total pollination than previously thought (Rader et al 2016;Page et al 2021). Floral abundance and richness are important for crop pollination services from unmanaged flower visitors (Kremen et al 2007;Garibaldi et al 2014), thus wild pollinator communities should be supported by increasing the floral abundance and richness in their environment.…”