Peter wrote:

> ...though numerous studies have characterized the immune responses
> of insects to pathogens, comparatively little is known...


This is absolutely true--but studies on other organisms like plants  
and other animals show that globalization with the massive movement of  
organisms (read micro-organisms) introduce unique interactions such  
that the "new" or unexposed host has little or no biological  
immunity.  There are parallels to be drawn which will help identify  
some of these complexities.

We are just really getting a sense of the catastrophic affect of  
introductions of organisms that are not indigenous to a new host.  I  
was reading an article some years back that hypothesized that the  
bubonic plague may have been due to introduction of a new strain of  
plague from the new world via import ( to Europe) of beaver pelts by  
way of North European explorers, maybe vikings--way prior to  
Columbus-- They hypothesized this was the reason for such a huge  
reaction by the host population in Europe, 1/3 died.  The organism was  
a new organism that the host population had little immunity because  
they had never before been infected with this specific organism.   
Conditions had probably been dirty before this time & rats had been  
around--what triggered this catastrophe?  It looks very much like a  
new introduced pathogen response to a population without immunity.


The list of these novel interactions and the speed at which organisms  
are being discovered -viral, bacterial, arthropod--you name it has  
really increased. Chestnut blight, Dutch elm disease, plum pox, soy  
rust, corn smutt, sudden oak death...--the list seems endless.  In  
part we are becoming ware of these because of new tools to separate  
these new organisms via DNA differentiation from very similar  
organisms that may only differ at a strain level.

As beekeepers we are seeing a huge increase in the number and speed at  
which new invasives are introduced (or discovered).  We missed some,  
more are out there waiting to be discovered & the way they are  
interacting is faster than how the industry is able to respond.  Many  
of our tactics have been developed 100 years ago & have not changed  
much if any.  We still burn AFB as best management or treat with  
antibiotics.

We are just seeing the tip of the iceberg for invisible invasives,  ie  
microscopic organisms like virus & bacterium, and  fungi &  
phytoplasms,  maybe and insect or mite born pathogen like a prion will  
be next.

Add in the complex life pathogen transmission in insects to cloud  
determination of organism.  For example,  some aphids acquire a virus  
by sucking on a plant.  The virus passes through the gut into the body  
of the insect and then migrates to the insects salivary glands where  
it is then re-injected into the plant.  The virus needs to be capable  
of  compromising two very different immune systems, that of a plant &  
that of an insect.  So is it a plant or insect virus?

Are some of the bee virus, we now know exist,  being selected by the  
mite immune system, ie passing through the mites where some mite DNA  
is added, or are they just mechanically transmitted?  Do bees acquire  
a virus when cannibalizing a pupae when extracting it from a cell?

I'm sure some of these issue will be broached in the coming years now  
that a host of new organisms have been detected in the states and they  
will certainly elucidate more of the Bee immune system along the  
path.  I just hope we don't see too many more microscopic invasives!

Mike

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