Do hygienic colonies require treatments for diseases and mites?

Hygienic colonies will demonstrate good behavioral resistance to AFB and chalkbrood. This means that although hygienic colonies may become infected with these diseases, the bees will rapidly remove all evidence (clinical symptoms) of the diseases, so it appears they are completely healthy. In most cases, hygienic colonies will require NO treatments for AFB or chalkbrood; however, they will still require occasional treatments for the mites. With more widespread use of hygienic stock, however, bees will become more resistant to mites and will require fewer and fewer treatments. 

How do bees detect diseased brood?

Most likely, hygienic bees detect abnormal brood by detecting abnormal odors with their antennae. Our research has shown hygienic bees have a more acute sense of smell for the odor of diseased brood than do bees that do not express hygienic behavior (Masterman et al., 2001; Gramacho and Spivak, 2003; Spivak et al., 2003; Swanson et al., 2009)

How is hygienic behavior inherited?

Hygienic behavior is a genetic trait. The famous work of Dr. Walter Rothenbuhler in the 1960s showed that it is a recessive trait, meaning that the queens and the majority of the drones she mates with must carry the hygienic genes for the workers in the colony to express the behavior (reviewed in Spivak and Gilliam, 1998). However, modern genetic analysis is revealing that hygienic behavior is controlled by a number of genes in a complex way (Lapidge et al., 2002).

Important note about genetics

If you purchase a hygienic queen, it is important to know if the majority of drones she mated with also came from hygienic colonies. If the queen did not mate with hygienic drones, the workers she produces will not express the behavior, and your colony will not be hygienic (Arathi and Spivak, 2001). To increase the chances that hygienic queens mate with hygienic drones, the drones in most of the surrounding apiaries must come from hygienic colonies. Ask your queen producer about their drone producing colonies.