Pollination services at risk following declines of Swedish bumblebees

Jun 21, 2011
This is a Bombus hortorum specimen. Credit: Maj Rundlöf

Scientists from the Swedish University of Agricultural Sciences and the University of Lund have discovered that the community composition of bumble bee species and their relative abundances have changed drastically over the last 70 years in Sweden. Over the same period, the average seed yield of red clover has declined and variation in yield has doubled, suggesting that the current dependence on few species for pollination of red clover has been detrimental especially to stability in seed yield.

The study was published this week in the B - Biological Sciences and was provided within the frame of the project STEP – 'Status and Trends of European Pollinators' that is funded by the European Union Framework Program 7.

The lead author Riccardo Bommarco comments: "It is worrying to see evidence that previously common bumble bee species have become rare and even red-listed. It is possible that such changes in community composition precede extinctions. In our efforts to conserve species and manage ecosystem services is appears important to promote not only species-rich, but also more evenly composed communities of service-providing organisms."

Notable efforts were made from the 1940s to the 1960s to explore pollination and seed production of red clover (Trifolium pratense), which is an important forage crop that is dependent on by bumble bees for seed set. Detailed historic records from the 1940s and 1960s were compared to present data on relative abundances of species collected in 2008-2010 in 44 red clover fields across Sweden.

The results show that two species (Bombus terrestris and B. lapidarius) have increased from 40% in the 1940s to entirely dominate present communities with 89%. Other species, such as B. hortorum and B. pascuorum have decreased tenfold in relative commonness, from around 20% to 2% of the observed bumble bees in a flowering clover-field. Notable is also the decline for B. distinguendus from 11% to 0.7%. This species is currently listed as near threatened in Sweden.

Explore further: Aging white lion euthanized at Ohio zoo

add to favorites email to friend print save as pdf

Related Stories

US sees massive drop in bumble bees: study (Update)

Jan 03, 2011

Weakened by inbreeding and disease, bumble bees have died off at an astonishing rate over the past 20 years, with some US populations diving more than 90 percent, according to a new study.

Franklin's bumble bee may be extinct

May 26, 2009

(PhysOrg.com) -- Native pollinator specialist Robbin Thorp, emeritus professor of entomology at the University of California, Davis, just returned from a scientific trip to southern Oregon and Northern California ...

Bumble bee visits a fritillary

Jun 25, 2010

Bumble bees can see which fritillary has the most nectar. Pollination by the bees protects plants against moulds.

Bee species outnumber mammals and birds combined

Jun 11, 2008

Scientists have discovered that there are more bee species than previously thought. In the first global accounting of bee species in over a hundred years, John S. Ascher, a research scientist in the Division of Invertebrate ...

Recommended for you

A vegetarian carnivorous plant

Dec 19, 2014

Carnivorous plants catch and digest tiny animals in order and derive benefits for their nutrition. Interestingly the trend towards vegetarianism seems to overcome carnivorous plants as well. The aquatic carnivorous bladderwort, ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.