In Japan, native honeybees have evolved an affective defense strategy against giant Japanese hornets.?

Question

Imported European honeybees, howvever, are unable to defend themselves. Explain this in terms of coevolution.

Answer 1

Honeybees native to Japan have lived in the same communities as Japanese hornets for an evolutionarily significant period of time.  The honeybees have thus coevolved with the hornets - in this case, the honeybees have over time acquired a trait that is highly effective in protecting them against the hornets.  As they have been consistently interacting with the hornets, the honeybees have been facing selective pressures from the hornets for a long time.

European honeybees have never been exposed to this selective pressure, and thus by comparison to the Japanese honeybees they are easy targets for the hornets.  Even though the European honeybees may have genome that could generate the trait(s) so useful for Japanese bees, this trait has never been selected for.