‘Worrying’ research shows various pesticides in Irish bee pollen

19 Sep 2023

Image: © Joost/Stock.adobe.com

Some bee pollen contained harmful types of pesticides that had not been recently applied to the sampled fields.

New research paints a worrying picture about the impact different pesticides are having on Ireland’s various species of bees.

A new study undertaken by Trinity College Dublin and Dublin City University looked at crop pollen at 12 sites in Ireland to evaluate any residual pesticides. They also looked at the pollen collected from both honeybees and bumblebees in the same sites.

The results varied for each type of pollen, but suggested that the highest number of compounds and pesticide detections were in bumblebee pollen. This pollen also contained the most amount of neonicotinoid insecticides, which are believed to be harmful to types of bees and other animals.

But one of the most concerning elements of the study was that many of these detected pesticides had not been recently applied to the sampled fields. This suggests the chemicals may persist for a long time, or the residues came from exposed plants in other areas that were within the foraging range of bees.

Elena Zioga, a PhD candidate in Trinity’s School of Natural Sciences and first author of the study, said it is “very worrying” that the five neonicotinoids were detected in bumblebee pollen and not in crop pollen.

“Some of these pesticides, known to be particularly toxic, had not been applied in the fields we sampled for at least three years,” Zioga said. “This shows either that they persist for a long time in the field edges, where wildflowers grow, or that bees collected neonicotinoid-contaminated pollen from beyond the sampled fields.”

Zioga was also concerned by the fact that different bee species appear to be exposed to different types of pesticides. The study found that honeybee pollen was mostly contaminated with fungicides, while bumblebee pollen mostly by neonicotinoid insecticides.

“Essentially, this means that using honeybees as a reference for understanding the exposure to different pesticides cannot give a complete picture,” Zioga said. “What’s true for honeybees doesn’t seem to be true for bumblebees, and we know that both are important for the overall pollination service and for supporting healthy ecosystems.”

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Leigh Mc Gowran is a journalist with Silicon Republic