Henrik Smith
Professor
Konkurrens mellan honungsbin och vilda bin : – evidens, kunskapsluckor och möjliga åtgärder
Competition between honey bees and wild bees – evidence, knowledge gaps and possible interventions
Author
Summary, in English
Competition from honey bees on wild bees – effects, knowledge gaps and possible interventions.
In this review, we have compiled the European emp irical evidence available in the scientific literature on the effects of honey bees on wild bees through competition for food resources. We have also inventoried ongoing initiatives in northern Europe concerning competition between honey bees and wild bees. The inventory showed that in several countries work is underway, for example in Norway, Denmark and France.
There are a few scientific ongoing initiatives, but there are also collaborative and
communication projects between researchers and beekeepers. Our compilation shows that approximately half of the plant species that both honey bees and wild bees visit are used by both groups, which is a condition for competition to occur. High densities of honey bees can deplete the supply of pollen and nectar and affect the flower-visiting behavior and choice of host plants of wild bees. This indicates that competition occurs but does not reveal much about the long -term effects of competition on wild bees. The few studies that have examined the effects of honey bees on the reproduction of wild bees show varying results. Some studies have found negative effects on bumble bee colony development, which may be linked to impaired long-term population development. A large part of the empirical European studies showed that densities of wild bees decreased with high densities of honey bees, but not all. Some studies showed that the distribution of wild bees in the landscape changed as a result of competition, but no studies showed that wild bees changed their behaviour
with regards to when during the day they were foraging. While some studies do not show any effects on species richness or diversity, others show a reduced diversity of wild bees in the presence of honey bees.
We note that many of the European studies are correla tive, sometimes suffering from a lack of replication and control areas. We have only found a few well- replicated, experimental European studies with control areas, which means that the evidence base is thin. It is therefore difficult to draw any definite general conclusions about the long-term effects of honey beekeeping on wild bee populations, and the extent to which honey bees cause population declines in wild bees. However, the majority of the observational studies, as well as the well-replicated experimental studies whose evidence value is higher, unanimously point to negative effects of honey bees on wild bees. The results are largely in line with the literature reviews conducted with a global focus. It is
therefore of great importance to work further with the issue, both through focused research and development of tools to limit and mitigate negative effects and create conditions for coexistence between beekeeping and the presence of wild bees.
In order to mitigate the negative effects of honey bees on wild bees by resource
competition, studies suggest a careful considerations when adding honey bees to areas with endangered populations of wild bees that use the same host plants as honey bees, to apply the necessary distances to honey bee communities (up to 1.1 km) and to increase the amount of flowering resources.
To give recommendations on what can lead to the coexistence of productive beekeeping and the presence of wild bees, more knowledge is needed. Above all, there is a need for experimental studies that investigate how contrasting densities of honey bees affect wild bee fitness, in order to be able to assess how and when honey bees affect wild bees long-term populations. We emphasize the need for dose-response studies, in which the impact of gradients of honey bee densities are investigated with sufficient power to detect meaningful biological effects. Experiments are also needed to examine how flower resources in a landscape modifies competion.
In this review, we have compiled the European emp irical evidence available in the scientific literature on the effects of honey bees on wild bees through competition for food resources. We have also inventoried ongoing initiatives in northern Europe concerning competition between honey bees and wild bees. The inventory showed that in several countries work is underway, for example in Norway, Denmark and France.
There are a few scientific ongoing initiatives, but there are also collaborative and
communication projects between researchers and beekeepers. Our compilation shows that approximately half of the plant species that both honey bees and wild bees visit are used by both groups, which is a condition for competition to occur. High densities of honey bees can deplete the supply of pollen and nectar and affect the flower-visiting behavior and choice of host plants of wild bees. This indicates that competition occurs but does not reveal much about the long -term effects of competition on wild bees. The few studies that have examined the effects of honey bees on the reproduction of wild bees show varying results. Some studies have found negative effects on bumble bee colony development, which may be linked to impaired long-term population development. A large part of the empirical European studies showed that densities of wild bees decreased with high densities of honey bees, but not all. Some studies showed that the distribution of wild bees in the landscape changed as a result of competition, but no studies showed that wild bees changed their behaviour
with regards to when during the day they were foraging. While some studies do not show any effects on species richness or diversity, others show a reduced diversity of wild bees in the presence of honey bees.
We note that many of the European studies are correla tive, sometimes suffering from a lack of replication and control areas. We have only found a few well- replicated, experimental European studies with control areas, which means that the evidence base is thin. It is therefore difficult to draw any definite general conclusions about the long-term effects of honey beekeeping on wild bee populations, and the extent to which honey bees cause population declines in wild bees. However, the majority of the observational studies, as well as the well-replicated experimental studies whose evidence value is higher, unanimously point to negative effects of honey bees on wild bees. The results are largely in line with the literature reviews conducted with a global focus. It is
therefore of great importance to work further with the issue, both through focused research and development of tools to limit and mitigate negative effects and create conditions for coexistence between beekeeping and the presence of wild bees.
In order to mitigate the negative effects of honey bees on wild bees by resource
competition, studies suggest a careful considerations when adding honey bees to areas with endangered populations of wild bees that use the same host plants as honey bees, to apply the necessary distances to honey bee communities (up to 1.1 km) and to increase the amount of flowering resources.
To give recommendations on what can lead to the coexistence of productive beekeeping and the presence of wild bees, more knowledge is needed. Above all, there is a need for experimental studies that investigate how contrasting densities of honey bees affect wild bee fitness, in order to be able to assess how and when honey bees affect wild bees long-term populations. We emphasize the need for dose-response studies, in which the impact of gradients of honey bee densities are investigated with sufficient power to detect meaningful biological effects. Experiments are also needed to examine how flower resources in a landscape modifies competion.
Department/s
- Centre for Environmental and Climate Science (CEC)
- Biodiversity and Conservation Science
- Lund university sustainability forum
- Biodiversity
- BECC: Biodiversity and Ecosystem services in a Changing Climate
Publishing year
2022-01
Language
Swedish
Publication/Series
CEC rapport nr 6
Links
Document type
Report
Publisher
Media-Tryck, Lund University, Sweden
Topic
- Ecology
Status
Published
Report number
6
Research group
- Biodiversity and Conservation Science
ISBN/ISSN/Other
- ISBN: 978-91-987132-0-6