Selection of hygienic colonies for disease resistance in Argentina (adapted from Bedascarrasbure et al., 2009). (a) Percentage of colonies expressing a high or low AFB prevalence in the population in 1997 (2935 colonies observed) and 2008 (9971 colonies observed). (b) Percentage of hygienic and non-hygienic colonies in the population, before the start of the ProApi national selection program and 5 years later. (c) Percentage of colonies with brood diseases in populations of hygienic and non-hygienic colonies. (d) Percentage of colonies with AFB symptoms in populations of hygienic and non-hygienic colonies.