I hardly find investigating the potential medical benefits
of black fly saliva to be much of a purpose.
Otherwise, using black fly larvae a a natural fish feed as I have posted
on in the past is much more
convincing. Seasonal changes naturally
suppress fish populations that are not presently in balance with their feed
supply of insect larvae during the warm months.
This leads to intense insect infestation during the high season. The
answer is surely to integrate fish husbandry into the cycle so that enough fish
are available early enough to consume the majority of larvae. This will fatten the fish through to the
first frost upon which feeding and harvest takes over.
Every standing water pond needs to be actively farmed in
this way simply to suppress the insect population. Recall how scarce insects can become in the
urban environment. That may be a
possibility even in actively managed agricultural environments to at least some
degree if we go after the natural feedstock that insects provide.
Out of this, I suspect that the natural default protein for
an expanding human population is easily fish.
We have already pretty well maxed out the use of our herbivores as
protein suppliers and further gains will be incremental and that also really
applies to boreal forest moose husbandry, which is the remaining unexploited
option available. It may be doublable
but beyond that looks effectively impossible.
Fish is clearly another matter altogether. They consume insects and we can easily
optimize supply there where nature needs a hand. The boreal forest alone worldwide could
readily produce tens of millions of tons of fish product. Otherwise, all other wetlands and waterways
are prospective for husbandry.
More practically, every farmer should be able to produce a
ton a fish integrated into his farming operation just as every farmer could
raise a hundred chickens if he wanted to.
Both are a simple husbandry that at this size level are not distorting
to the operations of the farm.
Black flies may have a purpose
after all
by Staff Writers
Athens, GA (SPX) Apr 12, 2012
Black flies are blood-sucking
insects who vector disease, like River Blindness, while feeding on humans.
Black flies drink blood and spread disease
such as river blindness-creating misery with their presence. A University of
Georgia study, however, proves that the pesky insects can be useful. Don
Champagne, an entomology professor with the UGA College of Agricultural and
Environmental Sciences, discovered a way to use the black fly's blood-sucking
tactics for medical advancement. The results of his research were published in
the journal PLoS One.
"In order to feed on blood, these insects
have to contend with our natural defense agents against blood loss-like
clotting," Champagne said. "Many insects use salivary injections
packed with proteins to inhibit the enzymes in our bodies from reacting the way
they normally would to injury."
In order for insects to earn a blood meal,
they have to override the human body's battery of defenses. Most of these
insects have anticoagulants to fight off clotting, inhibitors to stop clumping
of platelets and vasodilators to speed up blood flow at the bite site.
"As it turns out, there are also a lot of
things in saliva that modulate the immune response like inflammatory responses
and downstream immune responses," he said.
A few years ago, Champagne worked on a study
transcribing the messenger RNA that codes for proteins found in the salivary
secretions of the black fly. He found two proteins that looked like they could
hinder clotting. Champagne determined that one of these inhibits the clotting
cascade by blocking factor Xa.
Clotting factors exist in the blood in an
inactive state, waiting to be called into action. Because these factors work
like dominos, if factor X fails to be turned on (converted to Xa) the rest of
the responses stay inactivate.
"We were able to show that the
salivary protein targets Xa and is a good inhibitor of clotting," he said
about his recent research. "But, it is an even better inhibitor of some
enzymes involved in very early immune response-elastase and cathepsin G."
These enzymes are able to kill bacteria, and
they help drive the inflammatory response.
"We were expecting these to be
anticoagulants, that wasn't a surprise," he said. "But, we were
surprised to learn that the protein affected all of these other
responses."
This discovery made the protein attractive as
a potential drug target, possibly one to treat patients recovering from heart
attacks.
"Inflammation is a major source of tissue
damage associated with vascular injuries," he said. "The idea of a
single factor that could both inhibit clotting and inhibit damaging
inflammation responses at the same time is pretty novel and interesting."
Studying black flies is easier at UGA than
anywhere else, because UGA has the only black fly colony in the world. The
flies in the lab aren't the same ones that transmit the debilitating river
blindness disease, but the unique resource enables important research about the
transmission of river blindness.
"We are not rearing black fly vectors;
they are not being infected with the parasite that causes river blindness; and
there is no risk to the public," he said.
What they are doing is learning more about how
the disease is transmitted and how to possibly stop it.
"A lot of blood feeders also vector
diseases," Champagne said. "When they are playing all of these tricks
on the host in order for them to get a good blood meal, they change the
conditions at the point where these pathogens go into the skin. Those changes
often favor the pathogen. In an environment where normal wounding responses and
defenses are inhibited, the pathogen can go in and say 'oh, look at that-the
door is wide open."
Black flies vector river blindness while
drinking their blood meal. A threat in sub-Saharan Africa, river blindness is a
parasitic disease caused by a nematode infection. It's not caused by nematodes
themselves. A symbiont that the nematode releases when it dies triggers an
inflammatory response that causes changes in the skin and chronic inflammation.
Eventually, the symbionts migrate through the eyes, causing the cornea and lens
to cloud and leave infected people blind.
"These salivary factors change the
environment for the parasite so it's conceivable that knowing about this
protein would allow us to target it in some way, maybe by vaccinating against
it, and that would likely make it less favorable for the transmission of river
blindness," he said.
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