Days after EU authorities made an official announcement on partial restrictions covering three neonicotinoid pesticides, which the bloc's risk assessment body found pose a threat to honeybee populations, EFSA has linked another insecticide with harmful effects on insect pollinators.

The European Food Safety Authority announced on Tuesday that insecticide fipronil, which belongs to the phenylpyrazole family, poses "a high acute risk to honeybees when used as a seed treatment for maize." The findings were delivered following an assessment requested by the European Commission.

Fipronil is manufactured in the EU by BASF and is sold as Regent for use in horticulture. The pesticide is not as widely used in Europe as the neonicotinoids examined by EFSA earlier this year, although several EU states do use fipronil products as maize seed treatments.

EFSA looked at the acute and chronic effects of the pesticide on colony survival and development and the effects of sublethal doses on bee mortality and behaviour. The authority's pesticide risk assessment experts concluded that bees could be put at risk from exposure to dust drift and through nectar and pollen foraged from plants where fipronil had been used as a seed treatment.

EFSA added that risk assessments examining the effects of dust drift from field crops other than maize (including sunflowers) could not be completed. The Authority also said that evidence of a risk posed to bees from nectar and pollen from sunflower and maize crops grown with a fipronil seed treatment was inconclusive.

Risk assessment experts used data submitted for the approval of fipronil at EU and national levels in their investigations. BASF said in a statement that it does not believe fipronil products have played a part in declines in bee populations observed in Europe and elsewhere.