Bee-killing pesticides have been banned for emergency use in the UK for the first time in five years after the government rejected an application from the National Farmers’ Union and British Sugar.

The neonicotinoid pesticide Cruiser SB, which is used on sugar beet, is highly toxic to bees and has the potential to kill off populations of the insect. It is banned in the EU but the UK has provisionally agreed to its emergency use every year since leaving the bloc. It combats a plant disease known as virus yellows by killing the aphid that spreads it.

Prof Dave Goulson, a bee expert at the University of Sussex, has warned that one teaspoon of the chemical is enough to kill 1.25bn honeybees. Even at non-fatal doses it can cause cognitive problems that make it hard for bees to forage for nectar and the chemicals can stay in the soil for years.