Last year, Mariano Higes, et al published a study that de-links IAPV from colony collapse in Spain. Further, they showed no linkage to imidacloprid, either. 

Short communication. The detection of Israeli Acute Paralysis virus (IAPV), fipronil and imidacloprid in professional apiaries are not related with massive honey bee colony loss in Spain.  Spanish Journal of Agricultural Research 2010 8(3), 658-661

Honey bee losses
are likely to be provoked by different causes but the
recent pandemic produces weakness, depopulation or
death clinical features are similar to those caused by the
emergent pathogen N. ceranae, known to be a shortterm
bee pathogen.

Along similar lines, well-known pathogens like
V. destructor, one of the main pathogens of A. mellifera,
can cause a similar illness and act as a re-emerging agent
if not suitably controlled. 

In our country, the combination
of both pathogens and the highly pathogenic
viruses associated with them could increase the risk
of death in infected colonies, without pesticides exerting
a significant effect.

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