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Insect pollination is crucial for the maintenance of natural and managed ecosystems but the functioning of this ecosystem service is threatened by a worldwide decline of pollinators. Key factors in this situation include the spread and interspecific transmission of pathogens worldwide through the movement of managed pollinators. Research on this field has been mainly conducted in some particular species, while studies assessing the interspecific transmission of pathogens at a community level are scarce. However, this information is pivotal to design strategies to protect pollinators. Herein, we analysed the prevalence of two common microsporidia pathogens of managed honey bees (Nosema ceranae and N. apis) in bee communities of semiarid Mediterranean areas from the Southeast of the Iberian Peninsula. Our results confirm the ability of N. ceranae to disperse across wild bee communities in semiarid Mediterranean ecosystems since it was detected in 36 Apoidea species (39% of the sampling; for the first time in nine genera). The prevalence of the pathogen did not show any phylogenetic signal which suggests a superfamily host range of the pathogen or that wild bees may be acting only as vectors of N. ceranae. In addition, N. apis was detected in an Eucera species, which is the second time it has been detected by molecular techniques in a host other than the honey bee. Our study represents the primary assessment of the prevalence of microsporidia at community level in Mediterranean areas and provides outstanding results on the ability of Nosema pathogens to spread across the landscape. [ABSTRACT FROM AUTHOR]

Abstract: The recent decline in honey bee colonies observed in both European countries and worldwide is of great interest and concern, although the underlying causes remain poorly understood. In recent years, growing evidence has implicated parasites and pathogens in this decline of both the vitality and number of honey bee colonies. The Iberian Peninsula provides an interesting environment in which to study the occurrence of pathogens and parasites in the host honey bee populations due to the presence of two evolutionary lineages in A. m. iberiensis (Western European [M] or African [A]). Here, we provide the first evidence linking the population structure of the Iberian honey bee with the prevalence of some of its most important parasites and pathogens: the Varroa destructor mite and the microsporidia Nosema apis and Nosema ceranae. Using data collected in two surveys conducted in 2006 and 2010 in 41 Spanish provinces, the evolutionary lineage and the presence of the three parasitic organisms cited above were analyzed in a total of 228 colonies. In 2006 N. apis was found in a significantly higher proportion of M lineage honey bees than in the A lineage. However, in 2010 this situation had changed significantly due to a higher prevalence of N. ceranae. We observed no significant relationships in either year between the distributions of V. destructor or N. ceranae and the evolutionary lineage present in A. m. iberiensis colonies, but the effects of these organisms on the genetic diversity of the honey bee populations need further research. [Copyright &y& Elsevier]