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Smaller strawberries after pollination by red mason bees that have ingested the neonicotinoid clothianidin

Två rapsfält med en grusväg mellan. Foto.

Wild bees that ingest the neonicotinoid clothianidin when they feed from nectar of rapeseed flowers grown from clothianidin-coated seeds, become lethargic. In addition, strawberries pollinated by these bees become smaller. These are the results of a study conducted by three BECC researchers at Lund University.

Wild and managed bees are important providers of pollination services and benefit the production of various insect-pollinated crops. Neonicotinoids are a group of insecticides, which is associated with reduced bee reproduction and declining wild bee populations. Due to concerns about bees and crop pollination, the outdoor use of three different neonicotinoids is now restricted in the European Union, but in many other countries these compounds are still being used. And although clothianidin is now banned, other agents that affect the nervous system of insects in a similar way are used.

Slower bees and smaller strawberries

Most of the studies on how neonicotinoids affect bees have focused on either bumblebees or honeybees. In this study, the BECC researchers Lina Herbertsson, Björn K. Klatt, Maria Blasi, Maj Rundlöf and Henrik Smith, tested if exposure via treated rapeseed alters the foraging behavior of the red mason bee, and if this might impact pollination services in a nearby crop – in this case strawberries. What they found was that neonicotinoid clothianidin slowed down the bees and impaired their ability to pollinate the strawberry flowers, resulting in smaller strawberries. However, the study could not show a relation between the smaller weight and reduced foraging activity, highlighting the importance of understanding complex effects of plant protection products, which could have wider consequences than those on directly exposed organisms. 

Further reading

The research article is published in PLOS ONE:

Seed-coating of rapeseed (Brassica napus) with the neonicotinoid clothianidin affects behaviour of red mason bees (Osmia bicornis) and pollination of strawberry flowers (Fragaria × ananassa)

Article about the study in Swedish published at

Små jordgubbar efter att bin fått i sig bekämpningsmedel från raps

Learn more about the researchers in Lund Research Portal

Lina Herbertsson

Björn Klatt

Maria Blasi