Neonics, as they are commonly called, are systemic pesticides. Unlike contact pesticides, which remain on the surface of the treated foliage, systemic products are taken up by the plant and transported to all the tissues (leaves, flowers, roots and stems, as well as pollen and nectar). Products containing neonics are most often applied in this country to the seed as a coating, which means that the amount of the chemical is tiny, yet highly targeted. The insecticide toxin remains active in the plant, protecting it for at least six weeks.
We know that neonics are acutely toxic to bees and other pollinator species when they have direct contact or are taken by mouth. However, the question is when neonics are applied to the seed, are they still harmful to pollinators because the insecticide may be present in pollen and nectar at levels sufficient to impair bee health, including disruption to foraging behaviour, homing ability, communication and larval development?
Laboratory studies point to subtle sub-lethal adverse effects on bee brains, individual bees, or colonies, but so far these effects have not been seen in the field. The ban on neonics means that UK farmers who grow oilseed rape in particular may well revert back to overall insecticide spraying, as occurred 10 years ago, which may in fact be worse for pollinating species, including bees.
Both the British Beekeepers Association (BBKA) and the Bumblebee Conservation Trust did not call for an immediate ban on neonicotinoids, having major concerns that should the use of these products be restricted, they would be replaced by more hazardous, older products. However, both call for urgent further research and monitoring to be carried out.