With the original host of varroa apis cerana a. Cerana 
was able to keep varroa at bay because varroa rarely reproduced
in cerana worker brood and with hygienic
type behavior.
Varroa growth was slowed when the cerana hive was not raising drone brood.

When beekeepers started keeping cerana and mellifera 
together varroa  quickly found
mellifera the prefered host.

I might add research out of the U.K. (Dr. Carrick) suggests a hive can do quit well
with varroa *if* virus and problems the
Mite vectors are not an issue.

bob

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