Dr Nigel Raine, a bee researcher at Royal Holloway, has welcomed the result of an EU vote to introduce a ban of three pesticides believed to be harmful to bees.
He told ITV News it was "good news" and when the ban comes into effect it will be "crucial" to monitor bee populations to make sure it is effective.
He added that "we need to think about what we're going to use instead".
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The study by the National Childbirth Trust and National Federation of Women's Institutes found a lack of staff left some women frightened.
Extracts released by 10 Downing Street suggest Mrs May will say the UK will not settle for a "half-in, half-out" policy.
Milder for most of us