Honey bees in East Africa resist pathogens

Scientists have discovered that bees in Kenya have strong resistance to the same pathogens responsible for the deaths of billions of bees elsewhere in the world. Entomologist Elliud Muli, (ICIPE) with researchers at Penn State University, USA surveyed hives in all of Kenya’s major ecosystems: savanna, mountains, tropical coast, and desert. They measured the size of colonies and the numbers of bees and tested them for parasites and pesticide contaminants.

In a paper published in the online journal PLOS ONE, the researchers report that honey bees in Kenya are infested with the same pests and diseases that wipe out colonies elsewhere but do not succumb. Colonies remain healthy even where a combination of pathogens are present. “That resilience - I was amazed by the lack of manifestation of ill health in the bees,” said Muli.

Muli and Penn State co-author Maryann Frazier first detected Varroa in Kenyan honey bees in 2009. Nosema had not been seen there before, but in the recent study both pests proved prevalent in all but the most remote study areas surveyed.

“Finding Nosema at all was a big surprise, and finding out that Varroa was already so widespread was unexpected” said Christina Grozinger, Penn State. When we did the analyses on how the pests were impacting colony health, we did not see any significant effect.”

What explains the resilience of the East African bees? One source may lie somewhere in their genes, the researchers believe much of the explanation for the Kenyan bees’ resilience lies in different farm practices. African bees live relatively free of human input. The study found very low levels of only a few pesticides in hives, when there were any at all.

Beekeepers in Kenya should copy Western practices as little as possible, the study authors say, if they want to keep their bees healthy—and in particular refrain from treating them with pesticides even though Varroa and Nosema are present. For now, at least, “the wild Kenya bees have their own resistance,” Grozinger says. “It would be a mistake to interfere with that.”

Muli says: “The way beekeeping is done in the West has eroded the genetic pool through commercial breeding of queens and propping up sick colonies through use of medication - colonies which would otherwise be long dead. For us, instead, it is survival for the fittest, and Mother Nature seems to be getting it right. She is giving us a broad genetic pool of honey bees capable of dealing with any environmental shock.”

Source: Jennifer S Holland, www.news.nationalgeographic.com