Hou, C., Entomology Department, Institute of Plant Protection, The Volcani Center, Bet Dagan, 50250, Israel
Rivkin, H., Entomology Department, Institute of Plant Protection, The Volcani Center, Bet Dagan, 50250, Israel
Slabezki, Y., Beekeeping Division, Extension Service, Israeli Ministry of Agriculture, Bet Dagan, 50250, Israel
Chejanovsky, N., Entomology Department, Institute of Plant Protection, The Volcani Center, Bet Dagan, 50250, Israel

The determinants of Colony Collapse Disorder (CCD), a particular case of collapse of honey bee colonies, are still unresolved. Viruses including the Israeli acute paralysis virus (IAPV) were associated with CCD. We found an apiary with colonies showing typical CCD characteristics that bore high loads of IAPV, recovered some colonies from collapse and tested the hypothesis if IAPV was actively replicating in them and infectious to healthy bees. We found that IAPV was the dominant pathogen and it replicated actively in the colonies: viral titers decreased from April to September and increased from September to December. IAPV extracted from infected bees was highly infectious to healthy pupae: they showed several-fold amplification of the viral genome and synthesis of the virion protein VP3. The health of recovered colonies was seriously compromised. Interestingly, a rise of IAPV genomic copies in two colonies coincided with their subsequent collapse. Our results do not imply IAPV as the cause of CCD but indicate that once acquired and induced to replication it acts as an infectious factor that affects the health of the colonies and may determine their survival. This is the first follow up outside the US of CCD-colonies bearing IAPV under natural conditions. © 2014 by the authors; licensee MDPI, Basel, Switzerland.