Bumblebee exposure to pesticides can lead to poorer crops

Emily Chung
CBC News : November 18, 2015

Bumblebees exposed to common neonicotinoid pesticides may do a poorer job of pollinating crops such as apples, leading to poorer-quality fruit, a new Canadian-led study suggests.

When apple trees were pollinated by bees exposed to those pesticides, commonly called neonics, the trees produced about a third fewer seeds.

The number of seeds is generally linked to fruit quality in apples – apples with more seeds tend to be larger, firmer, tastier and more symmetric, said Nigel Raine, the University of Guelph researcher who led the study with his postdoctoral researcher Dara Stanley.

Apples with fewer seeds are more likely to end up as lower-value products such as applesauce.

“Bumblebees are essential pollinators of many important crops other than apples, including field beans, berries, tomatoes and oilseed rape,” the researchers wrote in a paper published today in the journal Nature.

“If exposure to pesticides alters pollination services to apple crops, it is likely that these other bee-pollinated crops would also be affected. Most importantly, the majority of wild plant species benefit from insect pollination services.”

Raine said that means the findings might be “really important… not just in terms of economics and food production of agriculture, but also thinking about biodiversity more broadly.”
Costs of pesticide use

Overall, the information suggests that using neonics has costs – to both production of other crops and wild ecosystems – that may not have previously been considered when weighing the costs against the benefits of using the pesticides.

Neonics, or neonicotinoids, are widely used to treat seeds of crops such as canola, corn and soybeans. The pesticide ends up in the entire plant as it grows, making it resistant to many insect pests.

Many studies have shown that exposure to neonics has a negative impact on the behaviour and reproduction of bees. That has prompted restrictions on neonics in some places, such as Europe and Ontario.

Because bees are so important for crop production, Raine said, he and his colleagues were interested in finding out whether the effects on bees might translate into effects on crop production.

(read the full article at CBC)

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