Narrator: This is Science Today. European honey bees pollinate more than 100 different crops in this country, which are worth 15 billion dollars a year. So, reports of a sudden decline of these busy bees have distressed the agricultural industry. But Claire Kremen, a conservation biologist at the University of California, Berkeley, says this is not new.
Kremen: For the past fifty years there was already this decline. It's a long-term trend, something that had been worrying people who care about bees, people who care about agriculture, for a long time.
Narrator: This steady decline was due to an invasive mite, but in the last year or so, honey bees have simply disappeared - some beekeepers have lost between 30 and 90 percent of their colonies due to colony collapse disorder.
Kremen: So what is colony collapse disorder? We don't know, but it turns out, looking back in the literature, some people have found that this is not the first time that this has happened. There are reports of it going centuries back of this disappearing disease. But it's come back in force.
Narrator: Kremen is helping California farmers use native bees as pollinators instead and has found that native bees motivate honey bees to work more. For Science Today, I'm Larissa Branin.