A range of pesticides, including neonicotinoids, have been found in the pollen of different bee species, according to Trinity College Dublin research.

The research, Trinity said, paints a worrying picture for the different species of bees that provide multi-million euro pollination services in Ireland each year.

The study looked at the potential widespread exposure to multiple chemicals from both fungicides and neonicotinoid insecticides.

It took into account residues in crop pollen at 12 sites in Ireland and in pollen collected from honey bees and bumble bees from the same sites.

Key results

  • Most pesticides detected had not been applied recently to the sampled fields, suggesting that some chemicals may persist for a long time and/or residues may have come from plants exposed to pesticides in other places but within the foraging range of bees.
  • Crop pollen was only contaminated with fungicides; honey bee pollen was mostly contaminated with fungicides; bumble bee pollen mostly by neonicotinoid insecticides
  • The highest number of compounds and most pesticide detections were in bumble bee pollen.
  • All five neonicotinoid insecticides assessed were found in bumble bee pollen – even though these had not been applied recently to the sampled fields.
  • PhD candidate in Trinity’s school of natural sciences Elena Zioga is the first author of the just-published journal article.

    She said: "The results of this study are concerning on several levels. Of particularly great significance is the indication that different species seem to be exposed to pesticides differently based on the variation in the types and number of different pesticides found in pollen of honey and bumble bees respectively."

    It is also very worrying, she added, that the five neonicotinoids that were looked for appeared in bumble bee 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."

    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, she added.

    "Our work also showed that neonicotinoid detection increased when the presence of wild plants in bumble bee pollen increased and that is one of many things that require further investigation," she concluded.