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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