In vivo test for spore viability

Experimentally, the viability of N. apis spores can be assessed by feeding suspensions with different spore concentrations to groups of newly emerged adult honey bees (see section Honey bees exposed to spores can be collected 10 days post infection when the infection appears to be almost fully developed for both Nosema spp. (Higes et al., 2007; Martin-Hernandez et al., 2011; Forsgren and Fries, 2010) and the ventriculus examined for the presence of spores. If spores are seen in the light microscope, the bee is recorded as infected (Malone et al., 2001) and the viability of the spores in the suspension used can be calculated based on the ID50 and the  ID100 obtained (see section