Beekeeper question of the week I heard that viruses are very dangerous than a
big problem in apiculture today because of a Varroa destructor but I also
heard from other researchers that honey bees can handle viruses very well. It
seems a contradiction to me, can you explain it? I think it can.
it seems a contradiction but in fact I would say it depends of the situation
let me explain. I'm going to Humberto Boncristiani and this is InsideTheHive.TV
the show that takes you into the world of bees. If you're new to the channel
welcome. We like to talk about bees here so if you enjoy bees and like to learn
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media. So addressing the question of my fellow beekeeper. I'm not sure where you
heard that or in which circumstances or which context but I think I know where's
the problem. Let me address first the second part of the question, the part
that said that honey bees can handle viruses very well and to address that I
want to invite you to come with me and to see the results of an experiment that
I have done many many times in my career. the experiment will answer a very simple
question. How many viruses do we need to make a bee sick? To perform such
experiment we're gonna to put a bunch of bees in cups, newly merged bees
so they have the same age and we're gonna feed them with viruses in
different concentrations and we're gonna wait from 3 to 5 days and wait to see
which concentration make them sick. The virus in this experiment is IAPV a very
old friend of mine. But keep in mind that the these numbers that I am going to show
you might vary depending of the type of virus, the strain of the virus, and the
genetic of the bees. Ok let's start. One virus / Bee. Nope 10 viruses / Bee not yet
a 100 viruses / Bee, Nope 1000 viruses / Bee Not yet 10,000 viruses / Bee
Not even close, a 100,000 viruses per bee. NAAhhhh Okay,
1 million virus particles per bee. Nope. 10 million nope hundred million virus
particles/bee Yes. That's the number. To make a bee sick you need with these
virus with this specific strain of viruses, you need a hundred million
particles of viruses per bee to make them sick around three to five days.
What's the message here? the message here that bees can be very tolerant to
viruses. 100 million virus particles per bee is a very significant amount of
viruses that it's very difficult to find in nature. Only in drastic conditions
we might find such concentration of viruses. Yes it's might occur, but it's kind
of rare. But we're going to go back to this subject later.
Hold that thought. So now let me change something so I can show you something
interesting. Instead of feed the bees with the viruses let's now inject them
with the same concentrations of viruses and see the effect. Let's start it.
one virus / bee Nope, 10 viruses / bee Nope, a hundred viruses / bee no,
1,000 viruses/bee Yes, you only need 1,000 viruses/bee to make a
bee sick. If we inject it directly into the body.
Look how drastic the changes are. to cause the same amount of damage you need a
hundred thousand times fewer viruses. So, what is going on here? Along evolution
bees have faced viruses all the time. Viruses are not something new that just
arrived in nature recently. The bees that we have today is the result of natural
selection, meaning the bees that we have today have specific mechanisms
to deal with viruses. In the past the main way for honeybees to get viruses
infection was through the digestive system. Bees consume nectar, bees
collect things and share nectar with other bees so the digestive system was
the main inoculation road for viruses in the past. Therefore, the bees
that survived are the bees that have something special in the digestive
system to survive a virus infections. And today we know some of those things.
The digestive system is a very tough environment for viruses. We know
that the viruses have to pass through a different pHs, they have to pass through
different enzymes, they have to pass through beneficial microorganisms, and
other factors. The second level of defense even if they pass through the
digestive system and reach the cells they need to reach to start their
replication. Inside the cells bees have developed
mechanisms to defend themselves against viruses as well. We know that these can
produce antimicrobial peptides and also they have RNA interference mechanisms to
defend themselves against viruses. And even that the bees pass through
the digestive system, also replicating in the cell and escape from that and reach
hemolymph and spread. Because bees are so social and they have developed a third
level of security. Bees are able to do something just amazing. They feel they're
sick and they fly way to die alone, so they can protect the hive.
Isn't that amazing! So in this scenario when bees get viruses throughout the
digestive system which it was the main open door for viruses in the past we can
say that they are tough against viruses so they have plenty of defenses to deal
with viruses however when the little guy called Varroa destructor a mite that
feed on the fat bodies of honey bees they need to open wounds to get access to
the fat bodies and then allow viruses to get right in that and reach the
hemopymph passing through all those defenses just destroying all defenses
that were selected through millions of years. In one single shot
Varroa destructor just make the bees defenseless against viruses. And now you can
see the power of varroa destructor when varroa destructor decided to jump from a
Apis ceranae to Apis mellifera that was a complete game changer for virus
infections in honey bees. A good comparison is to build a castle with all
the defenses in the front door and then you forget the back door open and
the enemy just go through there. Now let's go back to that thought that I
asked you guys to hold before. Do you remember that I said that it was rare to
have a situation where the bees have that big amount of concentration of
viruses so adult bees through feeding could get sick. Well now
with Varroa destructor we have the situation inside the hive, because Varroa
destructor like to feed not only in adult bees, actually they prefer
larvae and pupae, which means they gonna be there cooking a lot of viruses and
die so the adult bees is going to need to deal
with those dead bodies that cannot fly away to protect the hives
anymore the workers are gonna need to deal with
that and dealing with that they're exposed to a gigantic amount of viruses.
So even that ,the protection they had before throughout feeding through
the protection that was selected through evolution is compromised as well
because the amount of viruses that we might have inside the hive right now is
too much. So that's it for today I hope with this video I could clarify the
contradiction a little bit. If you enjoyed this video please hit the like
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I'll see you guys in the next video. Thanks for watching, inside the hive.TV
the show about bees.