Mid-last year, the largest field study yet reported its long-awaited results. Nature reports that scientists from the Centre for Ecology and Hydrology (CEH) in the UK put honeybees, mason bees (Osmia bicornis) and bumblebees in 33 oilseed-rape fields. There were fields in the United Kingdom, Germany and Hungary. They used either neonicotinoid or neonicotinoid-free pesticide-treated seeds.
Unsurprisingly, bumblebees and mason bees fared less well with increased exposure to neonics. But the honeybee picture was more complicated. While in some cases neonics seemed to affect bee health, in others they didn’t. In the United Kingdom and Hungary, neonics seemed to reduce worker-bee numbers in honeybee hives. Also in Hungary, researchers saw fewer egg cells in these hives, a sign of reduced reproductive success. But in Germany the honeybee hives exposed to neonics had more egg cells, “a puzzling result” according to Nature.
Overall, the study concluded that neonicotinoids reduced bees’ ability to establish new colonies after winter. The journal editor’s summary of the paper came under the headline: “Damage confirmed”. And this is where the drama ensued – the agrochemical firms that funded the study did not agree. They interpreted the data differently, and made this clear to the press.