Honeybees disrupt the structure and functionality of plant-pollinator networks

Alfredo Valido,María C Rodríguez-Rodríguez,Pedro Jordano

doi:10.1038/s41598-019-41271-5

Alfredo Valido, María C Rodríguez-Rodríguez + Show 1 more

Open Access

https://doi.org/10.1038/s41598-019-41271-5

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Abstract

The honeybee is the primary managed species worldwide for both crop pollination and honey production. Owing to beekeeping activity, its high relative abundance potentially affects the structure and functioning of pollination networks in natural ecosystems. Given that evidences about beekeeping impacts are restricted to observational studies of specific species and theoretical simulations, we still lack experimental data to test for their larger-scale impacts on biodiversity. Here we used a three-year field experiment in a natural ecosystem to compare the effects of pre- and post-establishment stages of beehives on the pollination network structure and plant reproductive success. Our results show that beekeeping reduces the diversity of wild pollinators and interaction links in the pollination networks. It disrupts their hierarchical structural organization causing the loss of interactions by generalist species, and also impairs pollination services by wild pollinators through reducing the reproductive success of those plant species highly visited by honeybees. High-density beekeeping in natural areas appears to have lasting, more serious negative impacts on biodiversity than was previously assumed.

Highlights

The western honeybee (Apis mellifera) is an economically important species native to Eurasia and Africa, which has been introduced almost worldwide for crop pollination and honey production[1]
Given the difficulty in carrying out field experiments in absence of honeybees, these predictions remain untested, limiting our ability to predict if the structural networks change under beekeeping, and if so, the implications for plant reproductive success
As reported in previous studies, honeybees become relatively well integrated into the existing pollination network[18,26], by visiting a large number of plant species and with a high frequency of visits

Summary

Introduction

The western honeybee (Apis mellifera) is an economically important species native to Eurasia and Africa, which has been introduced almost worldwide for crop pollination and honey production[1]. The honeybee is considered a super-generalist pollinator that monopolizes a sizeable fraction of floral resources[10,18], and generally disrupts the interactions between wild pollinators and plants[10,19,20]. It promotes non-mutual dependences between partners[13], and increases both selfing and interspecific pollen deposition, impairing fruit- and seed-set[21,22]. The effects of honeybees on the overall plant-pollinator network structure and functioning remain largely unexplored in natural ecosystems (but see Magrach et al.[23]). These special conditions of absence of beehives allowed us the use of 2007 data as a control-year, with honeybees practically absent for the whole season (Methods, see Supplementary Information)

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