The BEE DOC will empirically and experimentally fill knowledge gaps in honeybee pests and diseases, including the 'colony collapse disorder' and quantify the impact of interactions between parasites, pathogens and pesticides on honeybee mortality. We will show for two model parasites (Nosema, Varroa), three viruses (DWV, BQCV, IAPV) and two pesticides (thiacloprid, t-fluvalinate) how interactions affect individual bees and colonies.