>>> [log in to unmask] 01/02/02 09:16PM >>>
> -----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?
>

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

The theory I remember from graduate school is that a disease or parasite
that has "co-evolved" with its host in one part of the world, when introduced
to a "related" host (maybe the same genus but a different species) in another
part of the world will most often be "more virulent" to the new host, agreeing
with the above statement.

The concept being that in order for a parasite to survive, its host population
must also survive.  If it killed all of its hosts, it would die out too.  Therefore,
a parasite that had co-evolved with the host that was to be controlled would
not be as effective a bio-control agent as one that had not.  It therefore
follows that Varroa would be a very effective bio-control agent for EHB, as
we see it is.

Layne Westover, College Station, Texas