Clarity on Honey Bee Collapse?

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Abstract
Over the past few years, the media have frequently reported deaths of honey bee (Apis mellifera L.) colonies in the United States, Europe, and Japan. Most reports express opinions but little hard science. A recent historical survey (1) pointed out that extensive colony losses are not unusual and have occurred repeatedly over many centuries and locations. Concern for honey bees in the United States has been magnified by their vital role in agriculture. The California almond industry alone is worth $2 billion annually and relies on over 1 million honey bee hives for cross-pollination. So what is killing honey bee colonies worldwide, and what are the implications for agriculture?