One of the main reason that the hygienic behaviour from apis melifera is far from perfect is that they didn't have the need to. There are so many ways they are

One of the main reason that the hygienic behaviour from apis melifera is far from perfect is that they didn't have the need to. There are so many ways they are treated for varroa all year round (except high season) with "chemicals". They were simply not forced to develop a distinct hygienic behaviour. But every treatment damages the hive and puts the bees on risk. Thats why, in the last years, the selected breeding "movement" started growing.