Several parasites and pathogens that devastate honeybees in Europe, Asia and the United States are spreading across East Africa, but do not appear to be impacting native honeybee populations at this time, according to an international team of researchers. The invasive pests include including Nosema microsporidia（微孢子目） and Varroa mites.

"Our East African honeybees appear to be resilient to these invasive pests, which suggests to us that the chemicals used to control pests in Europe, Asia and the United States currently are not necessary in East Africa," said Elliud Muli, senior lecturer in the Department of Biological Sciences, South Eastern Kenya University, and researcher at the International Centre of Insect Physiology and Ecology, Kenya.

The team first discovered Varroa mites in Kenya in 2009. This new study also provides baseline data for future analyses of possible threats to African honeybee populations.

"Kenyan beekeepers believe that bee populations have been experiencing declines in recent years, but our results suggest that the common causes for colony losses in the United States and Europe -- parasites, pathogens and pesticides -- do not seem to be affecting Kenyan bees, at least not yet," said Christina Grozinger, professor of entomology and director of the Center for Pollinator Research, Penn State. "Some of our preliminary data suggest that the loss of habitat and drought impacting flowering plants, from which the bees get all their food, may be the more important factor driving these declines."

According to Harland Patch, research scientist in entomology（昆虫学）, Penn State, not only are flowering plants important for honeybees, but the insects are important for plants as well.

"Honeybees are pollinators（传粉者） of untold numbers of plants in every ecosystem on the African continent," Patch said. "They pollinate many food crops as well as those important for economic development, and their products, like honey and wax, are vital to the livelihood of many families. People say the greatest animal in Africa is the lion or the elephant, but honeybees are more essential, and their decline would have profound impacts across the continent."

In 2010, the researchers conducted a nationwide survey of 24 locations across Kenya to evaluate the numbers and sizes of honeybee colonies, assess the presence or absence of Varroa and Nosema parasites and viruses, identify and measure pesticide contaminants in hives and determine the genetic composition of the colonies.

"This is the first comprehensive survey of bee health in East Africa, where we have examined diseases, genetics and the environment to better understand what factors are most important in bee health in this region," said Grozinger. The results appeared today in PLOS ONE.