Populations of four species of bumble bees, important pollinators of fruit and tomatoes in particular, have declined by more than 90% over the last twenty years in the United States. Significant decreases in the number of these insects were also observed in Europe and around the world in recent decades, according to a study published Monday, January 3 in the Proceedings of the National Academy of Sciences (PNAS), after three years of research .A high degree of infestation by a microscopic pathogen called Nosema bombi and low genetic diversity appear to be two causes of this dramatic population decline in the U.S.. Their cousins, the honeybees, known since 2006 as a depopulation called "Colony Collapse Disorder" or CCD hives suddenly empty without the causes have yet been determined with certainty.
The drones weigh less in the U.S. that honeybees, which pollinate more than 90 varieties of fruits and vegetables (apples, avocados, blueberries ...), production estimated at 15 billion dollars per year in total, accounting for one third of food production. But they nevertheless play an important role in North America for some crops especially berries like blueberries.
In Europe, like France and Germany, the drones are high to pollinate tomatoes and other vegetables grown in greenhouses, crops which weigh billions of dollars a year on the Old Continent, much more than in North America.
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