The number of returning marked bees, and of those, the number of returning pollen foragers observed at entrances to field colonies during daily 30-min observations for 3 independent trials.

Bees were introduced into field colonies after receiving either N. ceranae spores (Infected) or sucrose solution (Control) within 24 h after eclosion. Marked bees were counted once during the daily observation period. Marked foragers were collected without replacement. Counts between rows within category followed by different letters are significant for the marked pollen forager data (Chi-squared test, p<0.05).