Evaluation of colony losses in Israel in relation to the incidence of pathogens and pests

To evaluate symptoms, extent, and possible causes of colony decline and losses in Israel, we carried out (1) a survey of honeybee colony losses and potential causes via mail and phone; (2) systematic sampling of healthy and problematic beehives after requeening in the winter; (3) detection of Varroa and pathogens including, viruses and Nosema ceranae, by microbiological means and sensitive RT-PCR. From 58 beekeepers (46 000 colonies) interviewed, 40% complained of extensive colony loses during 2008. Examination and sampling for pests and pathogens of 113 hives in the winter of 2009 showed 35% of hives with Nosema and 21% with V. destructor. The most frequent viruses detected were Black Queen Cell Virus, Israeli Acute Paralysis Virus, and Deformed Wing Virus. A significant negative correlation was found between worker population in the hive and the presence of viral and Nosema infections.