Bees can be bred to hive-off parasites. Credit: (C) Simon Fraser/SPL

Honey bees can be bred to be more 'hiveproud'. New research indicates that bees that detect and remove the parasites now endemic in many of the world's hives might be a cheaper, greener alternative to using pesticides1.

The rise of pesticide resistance means many beekeepers wage a costly fight against the blood-sucking_ Varroa mite. A strain of 'hygenic' bees that can rid their hives of Varroa_ -infected larvae and pupae could be good news for the honey industry and for food crops such as apples, berries, melons and almonds that bees pollinate. Many farmers rent out their bees to place near these crops to boost yields.

The bees, bred by artificial insemination from an Italian colony by Marla Spivak and Gary Reuter of the University of Minnesota, St Paul, kept their hives mite light for up to a year without pesticides and retained comparable honey production to their more slovenly cousins. They were, however, overwhelmed when mites infested more than 15% of them.

"These bees would undoubtedly decrease our dependence on chemicals," says Troy Fore, executive director of the American Beekeeping Federation, "but would probably not eliminate chemical use altogether."

They may only be a millimetre long but Varroa mites sap bees' energy and productivity and can kill a colony within two years unless fought with expensive pesticides - pesticides that are increasingly ineffectual and that can also contaminate honey. Beekeepers are thus keen to find alternative ways to defend their hives against these tiny troublemakers.

Breeding promises to be an effective non-chemical option says Jeffrey Harris, a bee breeder with the United States Department of Agiculture in Louisiana. Breeders will have the most success with bees that fend off mites in several different ways. Those that can kick out infected larvae and pick mites off fellow adults, for example.

Unfortunately it will take years of field experiments to see how combining these traits will affect the bee and its honey production. Especially as beekeepers have been slow to buy up the few resistant stocks recently released on to the market.