The National Farmers' Union has submitted a revised application for the emergency use of neonicotinoid seed treatments – prompting renewed appeals from environmental campaigners.

Last month, the government rejected an application for the limited temporary use of the pesticides, which were banned by the European Union for crops such as oilseed rape, amid concerns over harmful impacts on bee health.

The NFU says key changes have been made to the application to answer questions from the Expert Committee on Pesticides.

The application is for 'a more targeted area' of England's oilseed rape crop, using AHDB (Agriculture and Horticulture Development Board) data showing pressure from cabbage stem flea beetle – a pest previously controlled using neonicotinoids.

NFU vice president Guy Smith said the problem was exacerbated by growing resistance to pyrethroid insecticides.

He said: 'I cannot overstate how vital neonicotinoid seed treatments are for protecting crops facing pressure from cabbage stem flea beetle.

'I am quite convinced that if next autumn we have a difficult establishment window for oilseed rape then many farmers are going to lose their crops without neonicotinoids.

'Evidence from research institutions such as Rothamsted clearly shows we have an increasing pyrethroid resistance problem in pests and this is well-evidenced with cabbage stem flea beetle. Farmers cannot control the pest in areas with high resistance without these critical seed treatments.'

Bee campaigners are urging Defra to reject the application, saying there are 'no special circumstances' which justify emergency authorisation.

They said recent scientific studies had added to the concerns about the impact of neonicotinoid pesticides on bees and other pollinators, and pointed to government figures which show the average UK oilseed rape yield rose nearly 7pc last year, in the first harvest after the ban was introduced.

Friends of the Earth's head of campaigns, Andrew Pendleton, said: 'Having last month turned down the NFU's application to use bee-harming pesticides, it would be doubly reckless to allow their use now and also completely unnecessary.

'Oilseed rape yields have actually risen since the ban on neonicotinoid pesticides was introduced, while the evidence of the harm these chemicals pose to bees has increased.

'Bees are essential for pollinating our crops – we can't afford to gamble with their future. The Expert Committee and the government must uphold the ban and keep these dangerous pesticides out of our fields.'