Labour will end exemptions for bee-killing pesticides that have already been outlawed in the EU but which the UK government has approved for four years in a row, the shadow environment minister has said.

This week, the government authorised the use of thiamethoxam, also known as Cruiser SB, on sugar beet crops – against the advice of its scientists, who said it would pose a threat to bees.

Prof Dave Goulson, a bee expert at the University of Sussex, has warned that one teaspoon of the chemical is enough to kill 1.25 billion honeybees.