A cross-sectional study was carried out in Galicia, NW Spain, in order to estimate the magnitude of honey bee colony losses and to identify potential risk factors involved. A total of 99 samples from 99 apiaries were collected in spring using simple random sampling. According to international guidelines, the apiaries were classified as affected by colony loss or asymptomatic. Each sample consisted of worker bees, brood and comb-stored pollen. All worker bees and brood samples were analysed individually in order to detect the main honey bee pathogens. Moreover, the presence of residues of the most prevalent agrotoxic insecticides and acaricides was assessed in comb-stored pollen. The general characteristics of the apiaries and sanitary information regarding previous years was evaluated through questionnaires, while the vegetation surrounding the apiaries sampled was assessed by palynological analysis of comb-stored pollen. The colony loss prevalence was 53.5% (CI 95% =43.2-63.9) and Nosema ceranae was found to be the only risk factor strongly associated with colony loss. The decision tree also pointed out the impact of the Varroa mite presence while variables such as apiary size, the incorrect application of Varroa mite treatments, and the presence of Acarapis woodi and Kashmir bee virus (KBV) were identified as possible co-factors.Additional key words: colony collapse; Apis mellifera; Nosema ceranae; Varroa destructor; imidacloprid; fipronil; comb-stored pollen.Correspondence should be addressed to Aránzazu Meana Mañes: ameana@ucm.es (Tables S1, S2 and S3) accompanies the paper on SJAR's website.

A nationwide survey was performed to study the distribution of parasites, pathogens and pesticides in managed honey bee populations in Ghana. When 45 colonies were sampled and inspected for signs of disease, Varroa destructor was the most prevalent parasite (89%; n = 40), all mites corresponding to the Korean haplotype of this pathogen. Aethina tumida (42%; n = 19) and Braula coeca (7%; n = 3) were also detected, as were Melissococcus plutonius and trypanosomatids (7%). By contrast, Nosema spp., Acarapis spp., Ascosphaera apis and Paenibacillus larvae were not detected by molecular screening. Amitraz was the most widely distributed pesticide (75%; n = 23) followed by coumaphos (47%; n = 15), chlorpyrifos (34%; n = 15) and fluvalinate (31%; n = 10). This survey lays the groundwork for further monitoring of honey bee populations in Ghana.