while they may not be our favorite part
about eating outside these are really
important to our ecosystem they're
prolific natural pollinators and are a
huge part of our modern agriculture i
mean a lot of the food we eat relies on
pollination from bees unfortunately
though they're also in serious danger
the scientists in our next film
symbiosis might have discovered one
cause and it could change everything we
know about bees and their ecosystems
starting with a microscopic world that
we never knew existed until now this is
symbiosis from days edge productions
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bees
for more than 100 million years they've
been buzzing around helping plants
reproduce we're kind of shoulder to
shoulder with bee populations in the
maintenance and sustenance of plants we
keep plants because we need them for
food
bees are in a similar relationship with
plants where they're
helping the plant and getting something
in return
bees collect pollen to feed to their
young lands and the larva eat the pollen
and develop into adults and that's what
we've always thought
but the more we look the more we realize
that bees have this
silent partner in their mutualism with
plants and that third silent partner is
the microbes
new research is revealing that these
microbes play a surprising role in the
lives of nature's most prolific
pollinators
but this discovery raises new questions
about the future of wild bees in a world
transformed by humans
if the microbial community is perverted
in some way it can have catastrophic
effects in terms of be health
it matters
because as with any symbiosis when you
remove one of the symbionts the
symbiosis crumbles
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i think when people hear the word bee
they typically think of honey bees
honey bees are not native to north
america we brought honey bees here in
the 1600s
spreading with european colonists
honeybees became the most abundant bees
on the continent
but there were already wild bees here
a lot of them
in north america we have four thousand
native bee species
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some of them are important crop
pollinators
some of them are also intimately tied to
pollination of native wildflowers and
native
plants whenever there's a flowering
plant there is a bee to visit that plant
and so that pairing that mutualism
between the bees and the plants that has
fed the literally and figuratively fed
the diversity of bees in north america
the vast majority of bees are solitary
ground nesting bees and by solitary i
mean a single female constructs her own
brood cell provisions it with pollen and
nectar defends it against parasites and
predators and lays her own egg
then the grub like larvae eat the pollen
and nectar their mothers provision them
with
and eventually transform into adult bees
when the weather conditions are right
when the rain comes or when the spring
comes those bees will emerge and they'll
start the cycle over again
but for many of north america's wild
bees this cycle isn't running as
smoothly as it used to
native bees are dwindling across the
continent
and the culprits behind their declines
have been hard to pin down
we started doing research on the native
bee fauna of apple orchards in around
2008
one of the things we detected is that
the species richness and the abundance
of bees declined with fungicide use
fungicides are agricultural chemicals
used to fight disease-causing fungi in
crops
but the link between fungicides and bee
health was puzzling partly because you
can't sell a fungicide in the u.s until
it's been safety tested on bees
there is a whole lot of data showing
that the fungicides are relatively
innocuous for the adult bee
if fungicides weren't killing the adults
there had to be another connection
but what was it
the first clue came from researchers
studying the life cycles of wild bees
starting from the very beginning
mom builds this little brood cell she
digs it out she lines it she puts food
in it she lays an egg on it
and that
world is
it's a nursery right
but mom
maybe intentionally maybe sometimes by
mistake maybe it's just part of being a
bee
mom introduces
bacteria she introduces fungi
and it gets sealed off and then it's
really literally its own ecosystem
an ecosystem we're only beginning to
explore
mother bees collecting pollen and nectar
also gather microbes like fungi and
bacteria
and whatever else is on the flowers they
visit
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we screened the pollen provisions and we
found up to 35 agrochemicals and about
half of those were fungicides
it got the scientists thinking
if bees bring fungicides into their
nests could those chemicals throw the
tiny brood cell ecosystem out of balance
and how would that affect the developing
bees
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to find the answer they first had to
figure out how bees interact with
microbes in healthy brood cells
we're here at the bodega bay marine lab
in northern california to study one of
north america's most interesting bees
anthophyra bomboys
these bees build massive aggregations so
we find
thousands of nests in one small area of
the cliff face
when we excavate a nest site we can
start getting a glimpse of what's going
on inside of each of those brood cells
so here's a brood cell
that we've just excavated out we see the
brood cell is quite a solid structure it
has a very very strong odor it smells a
little bit like
parmesan cheese or reggiano or cheetos
there's a fascinating chemical story
going on here
the pungent odor is a sign of microbes
at work
just like what happens when microbes
transform milk into cheese
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so we have in this vial some provision
that came from the brood cell in the
soil
the provision that smells like cheetos
once you put them on these plates you
can start to see some of the diversity
of forms and of colors and of types of
interactions of these microbes that
otherwise are remain unseen
take a sample from a brood cell let it
grow for a few days and
there they are
bacteria
fungi
it's likely
thousands of species of microbes
are all these different microbes just
getting a free meal in the brood cell
or do they somehow benefit the
developing bees
there's one way to find out
you knock out the microbes from the
fermenting pollen mass and then you see
how the bee actually fares how does that
larvae do
the researchers turned to osmia bees for
an answer
also known as mason bees osmia bees are
widespread solitary bees known to be
important agricultural pollinators
unlike most solitary bees they nest
above ground often in hollow plant stems
this makes osmia easier to study than
ground nesting bees
but the researchers still had to figure
out how to manipulate and observe larvae
that normally develop inside sealed
individual brood cells
how do we study these bees how do we see
what they're doing they develop in these
opaque chambers we don't know what's
going on in there and that's when we
started opening their nests and looking
at them
it just blew me away it it was there was
such a brilliant method it just appealed
to my type a personality i guess it's
almost like having your spice jar
organized alphabetically it was just
magnificent like that
after a few years of trial and error we
figured out that we could actually rare
these bees inside our lab inside these
belt trays and have better survivorship
than recorded in the wild
finally the researchers had a solitary
bee they could observe from egg to adult
as it grew in a clear plastic brood cell
what would happen if the bees pollen
provisions were sterilized removing the
bacteria in fungi but leaving the pollen
and nectar intact
and what we found is that when you
remove the microbes the developing
larvae just suffer woefully half of them
don't even make it to pupation those
that do tend to be small and sickly and
they take a long time to get there and
so
those appear to be uh huge consequences
for a bee that does not have its
microbes
the larvae developing without microbes
were starving
even with all the pollen and nectar they
could eat
so what was missing from their diet
if they're just eating pollen and nectar
bees are going to be
strictly herbivorous and that has a
specific like chemical signature if you
pluck a hair out of a vegetarian they're
going to have a different chemical
signature than somebody that only eats
red meat
in other words analyzing the molecules a
bee larva is made of can tell us what
it's been eating
we typically think of bee larvae as
vegetarians but in the tiny ecosystem of
the brood cell they have access to a
surprisingly diverse menu
we looked at all major
b families
and we found every single bee
was significantly omnivorous
they're eating huge amounts of this
microbial meat
it's not
very often that you think of microbes as
food but that's what we think is exactly
going on we think that the larva eat
pollen yes
but not nearly as much as they eat the
microbes that have eaten the pollen
and if you remove those meaty microbes
and force the larvae to become
herbivores
they suffer
it might so be that they consume the
pollen because they're trying to consume
the microbes and the pollen is just in
the way
it's i think a massive shift in our
understanding
beyond their role as a food source the
microbes could also benefit b larvae by
digesting the tough outer shells of
pollen grains
or even by neutralizing the defensive
chemicals present in some plants pollen
and nectar
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the researchers are testing these ideas
and more
whatever they find it's clear that the
ancient alliance between bees and plants
depends on a third partner that's been
hidden
until now
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we know from our research that there is
a broad diversity of fungi within pollen
provisions and we know that when they're
not there the bees suffer
which brings the scientists back to the
link between fungicides and b health
in the u.s alone we use more than 50
million pounds of fungicide each year
connecting the dots from those
supposedly be safe fungicides to
declining bee populations
sean realized that fungicides might not
harm bees directly but instead kill the
fungi they rely on
essentially taking microbial food from
the mouths of bee larvae
shawn and his students tested this idea
with a native social bee the common
eastern bumblebee
we set up an experiment where we had
bumblebees in really big cages and we
stocked them with lots of flowers
um some cages the flowers were sprayed
with fungicide some cages were just you
know sprayed with water then we tracked
how those bumblebee colonies did and we
saw this hugely negative effect on the
bumblebee colonies that had fungicide
residue on the flowers
the colonies foraging on fungicide
treated flowers had fewer workers and
smaller queens than colonies foraging on
untreated flowers
that monkey-wrenched microbial community
results in starving larvae
so if you ask the question
fungicides be safe not for the larva
and so definitely not
the data show that the standard practice
of testing fungicides only on adult bees
has a critical blind spot
and we might never have known it without
researchers exploring the hidden world
of the brood cell
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we're now looking at
how fungicides affect other bee species
specifically the solitary bees and we're
in the midst of that right now
researchers are carefully dosing
osmiabee's pollen provisions with
various fungicides in the lab mimicking
the real-world interactions of bee
larvae microbes and fungicides
their goal is to identify the threats
these chemicals pose to native
pollinators
we really rely a lot on some of these
agrochemicals
sadly if we stopped applying
agrochemicals our our food supply would
probably be in trouble
so the answer is not to stop all
fungicide sprays that's not the answer
the answer is to figure out a way where
spraying can be done in a manner that is
sustainable and compatible with bee
conservation
the scientists are optimistic that some
fungicides will be more bee friendly
our findings so far suggests that
not all fungicides are created equal
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some may cause fewer problems for bees
than others
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and beyond choosing less harmful
fungicides we can also adjust how we
apply these chemicals to our crops
we can spray crops before or after bloom
so there's less fungicide on the flowers
when bees are foraging or even spray at
night when most bees aren't active
one of the fruits of our work has been
to say hey microbes matter for bees
bees matter to you the growers so can we
do this better where we protect our
plants but also protect the pollinators
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and we're learning the protecting native
bees means protecting the microbes that
help them grow and thrive
the food we eat the air we breathe is in
some way shaped by these microbes
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you don't see them you don't know that
they're there
but
they shape every
every facet of our existence
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you