> -----Original Message-----
> From: adony melathopoulos [mailto:[log in to unmask]]
> Sent: Wednesday, January 02, 2002 3:35 PM
> To: [log in to unmask]
> Subject: Do bee disease evolve to be more benign?
>
>
[cut]
>
> The theory predicts that a disease like Varroa, that spreads
> easily among colonies, will evolve towards being more benign
> to bees, while AFB, that can lay dormant in the environment,
> being vectored by next cavities, will tend to be more virulent.
>

I think that there are other things to consider in this model.

If a new disease is introduced into a population and results in 100%
fatality then there is no room for evolution to do anything. Evolution
depends on random changes to DNA that result in traits that improve
survivability (or at least do not hinder it). If there is not enough
time, or enough population, then the random trait has little chance of
showing up.

If a mutated bacteria kills its host before it can spread, then it may
not last too long. In a dense host population the time needed to spread
could be only a few hours. I can see where bacteria that evolved to be
less deadly would be more visible to research under these conditions.

Consider the SHB. It can live outside the hive on rotting fruits and
vegetables. It can pressure the honeybee population as much as it wants
and still maintain a breeding population after the last hive in an area
is destroyed.

When a parasite jumps hosts the new host does not seem to do very well.