Beekeepers and their supporters gathered in Parliament Square today to urge the Government to support an EU-wide ban on certain pesticides.
The demonstration comes ahead of a vote in Brussels on Monday which will decide whether Europe introduces a two-year moratorium on various neonicotinoid pesticides.
One of the organisers Matt Shardlow, chief executive of nature conservation organisation Buglife, said:
Britain abstained last time and has made no commitment this time, but we want them to support a ban across Europe. Some 73% of the British public support a ban on these insecticides, we want the Government to follow their lead.
British bee farmers say numbers within some colonies have slumped by as much as 50% because of the long winter and last summer's wet weather.
ITV News Correspondent Rupert Evelyn reports:
Beekeepers dressed in their protective costumes for the protest and many protesters wore brightly coloured striped clothing.
Other organisers involved with organising the event included Friends of the Earth, Greenpeace, Pesticide Action Network UK, RSPB, and the Soil Association.
Fashion designers Dame Vivienne Westwood and Katharine Hamnett also backed the campaign, handing a petition at 10 Downing Street in support of their aims.
Friends of the Earth's head of campaigns Andrew Pendleton said that Ministers could not ignore the "growing scientific evidence" linking the pesticides to bee decline. He added:
Their claims to be concerned about bee health will ring hollow if they fail to back European moves to restrict the use of these chemicals.
An ever-growing number of the UK's leading retailers and manufacturers are recognising the threat these products pose by removing them from their shelves and supply chains - the Government must now act.
If we lose our bees and other vital pollinators it will have a devastating impact on our food, gardens and environment. We urgently need tougher pesticide restrictions and a British Bee Action Plan to tackle all the threats they face.
A spokeswoman for the Department for Environment, Food and Rural Affairs later commented:
As the proposal currently stands we could not support an outright ban. We have always been clear that a healthy bee population is our top priority, that's why decisions need to be taken using the best possible scientific evidence and we want to work with the Commission to achieve this.
Any action taken must be proportionate and not have any unforeseen knock-on effects.
The petition handed to 10 Downing Street was signed by 2.6 million people, including 600,000 in the UK, campaign organisation Avaaz said.
A spokesman for the organisation said that Britain is one of the few countries in Europe likely either to abstain or vote no on Monday when key officials meet to decide whether they will agree to the moratorium.
France, Spain and Italy are likely to back the ban and of the major countries, only Britain and Germany are expected to raise opposition to it.