Evaluation of the Distribution and Impacts of Parasites, Pathogens, and Pesticides on Honey Bee (<i>Apis mellifera</i>) Populations in East Africa

<div><p>In East Africa, honey bees (<i>Apis mellifera</i>) provide critical pollination services and income for small-holder farmers and rural families. While honey bee populations in North America and Europe are in decline, little is known about the status of honey bee populations in Africa. We initiated a nationwide survey encompassing 24 locations across Kenya in 2010 to evaluate the numbers and sizes of honey bee colonies, assess the presence of parasites (<i>Varroa</i> mites and <i>Nosema</i> microsporidia) and viruses, identify and quantify pesticide contaminants in hives, and assay for levels of hygienic behavior. <i>Varroa</i> mites were present throughout Kenya, except in the remote north. Levels of <i>Varroa</i> were positively correlated with elevation, suggesting that environmental factors may play a role in honey bee host-parasite interactions. Levels of <i>Varroa</i> were negatively correlated with levels of hygienic behavior: however, while <i>Varroa</i> infestation dramatically reduces honey bee colony survival in the US and Europe, in Kenya <i>Varroa</i> presence alone does not appear to impact colony size. <i>Nosema apis</i> was found at three sites along the coast and one interior site. Only a small number of pesticides at low concentrations were found. Of the seven common US/European honey bee viruses, only three were identified but, like <i>Varroa</i>, were absent from northern Kenya. The number of viruses present was positively correlated with <i>Varroa</i> levels, but was not correlated with colony size or hygienic behavior. Our results suggest that <i>Varroa</i>, the three viruses, and <i>Nosema</i> have been relatively recently introduced into Kenya, but these factors do not yet appear to be impacting Kenyan bee populations. Thus chemical control for <i>Varroa</i> and <i>Nosema</i> are not necessary for Kenyan bees at this time. This study provides baseline data for future analyses of the possible mechanisms underlying resistance to and the long-term impacts of these factors on African bee populations.</p>