A class of insecticide which is the most used worldwide, (ref) the chemicals protect against insects from chewing leaves and extracting sap. When applied to a plant, the plant absorbs the chemical into its tissue and expresses it through the whole of its biology, including the pollen. (ref) This has a negative impact on bees and other pollinators and due to this, the chemical is banned for outside use by the EU, (ref) the UK voting in favour of the ban. (ref) The only use of neonicotinoids can be inside a greenhouse, although there is worry the chemicals could still spread elsewhere. (ref)