1.1.1. Acute bee paralysis virus /Kashmir bee virus /Israeli acute paralysis virus
Acute bee paralysis virus (ABPV), Kashmir bee virus (KBV) and Israeli acute paralysis virus (IAPV) are three closely related viruses (de Miranda et al., 2010a) that are largely symptomless, but they can be lethal at individual and colony level (Allen and Ball, 1995; Todd et al., 2007), particularly when transmitted by Varroa destructor (Ball, 1985; 1989; Ball and Allen, 1988) which is an active vector of these viruses (Chen et al., 2004a; Shen et al., 2005a; 2005b; DiPrisco et al., 2011). These viruses are characterized by the ability to kill both pupae (after injection; Bailey, 1967; Bailey and Ball, 1991) and adult bees (after injection or feeding: Maori et al., 2007a; 2009; Hunter et al., 2010) very rapidly; 3-5 days after inoculation with sufficient virion loads. This exerts a strong negative selection pressure on the transmission by varroa, since infected pupae fail to complete development, preventing the release of infectious mites from the pupal cells (Sumpter and Martin, 2004). The association of these viruses with varroa infestation is therefore unstable and much influenced by the presence of other viruses that are better adapted to transmission by varroa.