Today's focus is on "Mosquitoes!"

Did you know that mosquitoes are actually the most deadly creatures to humans on Earth?

Mosquito-borne diseases like malaria and dengue fever kill more than 720,000 people every year.

Even in sub-tropical Japan, the numbers of disease-carrying mosquitoes are increasing

due to factors like rising population density and climate change.

Our more populous than ever Earth
is the ideal mosquito breeding ground.

In order to combat these troublesome mosquitoes,

research is being conducted from various angles worldwide.

Thanks to long years of study,

the ingenious life cycle of the mosquito has been made clear.

And we'll soon see practical applications that could benefit our daily lives.

Perhaps humanity's greatest enemy: the mosquito.

But we may be on the verge of tapping into its hidden power.

Hello and welcome to Science View.

I'm your host, Tomoko Tina Kimura.

Today's topic is the mosquito.

While naturally a threat to humans,

their study may lead to breakthroughs that benefit all of us.

With us today is Mr. David Hajime Kornhauser, Director of Kyoto University's Office of Global Communications.

Thank you so much for joining us.

It's my pleasure.

Now, to begin, there are two types of mosquitoes commonly found in Japan, is that correct?

The darker one is Aedes albopictus, which usually bites people in the daytime,

and then, the other one, Culex pipiens, or house mosquito, is active at night.

The diseases transmitted by mosquitoes include viral diseases like dengue fever,

and protozoan infections like malaria.

Found mainly in Africa, malaria infects over 200 million people annually,

while dengue fever, mostly in Southeast Asia and South America, affects about 96 million individuals per year.

There was actually an outbreak of dengue fever in Japan in 2014, wasn't there?

Yes, it's believed to have come in from abroad,

and the virus was then transmitted by Aedes albopictus.

So, the virus is found in mosquitos that commonly bite us?

It is. So, caution is required, not just in tropical areas, but here in Japan and other parts of the world too.

So, why do mosquitoes feed on our blood in the first place?

Let's find out.

With a short lifespan of just one month, the all-too-common mosquito.

Do you know their main source of food? The answer may surprise you.

It's believed that mosquitoes mostly live on foods like flower nectar and sap.

Professor Hirotaka Kanuka studies mosquito-borne diseases and the mosquito life cycle.

When we talk about mosquitoes,
everyone assumes they feed on blood,

but there are actually some
mosquitoes that don't do this.

Mosquitos that don't feed on blood are male.

They mainly eat nectar or tree sap.

So, what about the mosquitoes that actually do feed on blood?

Let's do an experiment.

Believe it or not, mosquito researchers regularly feed their subjects with their own blood.

Inside this mosquito net there are
about 250 to 300 females.

I feed about 2,000 in one day,
about once or twice a week.

It was pretty itchy at first, but now
I'm used to it, so it doesn't itch at all.

Here we have two cases, each with the same number of female mosquitoes, of two different species.

She first puts her hand in case A.

As expected, they quickly come in for a bite...

11 bites in total!

But after leaving her hand in case B for 10 seconds...

Just one mosquito comes in for a bite.

These mosquitoes seem to have no interest in biting at all!

In fact, only female mosquitoes that have already mated feed on blood.

The others are ones that haven't mated.

Blood is very rich in nutrients
needed in egg production.

This allows the eggs to be
produced quickly and efficiently.

This means more and more
new generations of mosquitoes.

So, it's a key survival strategy.

The mosquitoes that bite us
are actually all mothers to be.

So, mosquitoes feed on our blood so they can produce their eggs.

And look at this!

There's liquid coming from its bottom!

This is actually excess water from the blood that's being excreted.

The blood is concentrated, and eggs are made from the proteins that remain.

Only about 30% of the 110 known species of mosquitoes in Japan

actually consume human blood in this way.

And there's a significant difference in the number of eggs

between those that feed on blood and those that don't.

Aedes albopictus lays around
200 eggs after one feeding.

But mosquitoes that don't feed
on blood lay only 40-50 eggs.

Feeding on humans allows them to
produce 4-5 times as many eggs.

For the mosquitoes, feeding on human blood is worth the risk of being swatted.

Here in Japan, we commonly use things like mosquito repellent spray and mosquito coils to keep mosquitoes away,

but are there any other options?

Well, for example, in Brazil they've gone as far as using gene manipulation against them.

The program introduces genetically altered males into the wild

to breed with wild females and the larvae they produce die before reaching maturity.

Meanwhile in Japan,

research is underway to take advantage of one of mosquitoes' unique properties as a defense against them.

Here in this room belonging to a Tokyo area cosmetics maker, they're breeding...

...mosquitoes in massive numbers!

The lead researcher is Dr. Takao Nakagawa.

Believing it vital to prevent a sudden increase in mosquito-borne illness,

they began researching mosquitoes.

Surveys were done in areas like Thailand.

And in recent years, cases of dengue fever have risen,

with as many as 150,000 individuals infected in a single year.

Worse yet, infection is particularly common among children, sometimes resulting in death.

For households with young children,
daily pesticide use seems impossible.

The first step was finding out how
to prevent mosquitoes from biting.

They found that in places like Thailand, Indonesia, and Vietnam,

roughly 80 percent of the population are bitten by mosquitoes every day.

So, their current research is focused on developing safer and more reliable mosquito repellant technology.

They came upon a particular liquid unique to the cosmetics industry.

When a mosquito lands on the skin,

it normally takes about 0.2 seconds for it to assume a biting posture.

But apply this special liquid...

...and after the legs make contact, the mosquito withdraws in just 0.04 seconds.

Its escape response is being triggered.

But what is the liquid?

It's called silicone oil.

It's used in makeup, shampoo,
and all kinds of other products.

So, what is it about this oil that causes mosquitoes to flee?

Nakagawa focused on the mosquito's legs.

Close up you can see they're quite hairy...

As you can see, they're actually covered in tiny scales with minute ridges.

Mosquito eggs hatch near the water's surface and they grow in water in their larval stage.

And when they emerge from the pupal stage, they rest on the water's surface.

The ridged structures on their legs hold a layer of air that repels water, allowing them to float.

Mosquito legs are very water repellant,
making them highly attractive to oil,

which has opposite properties to water.

The legs' microstructure takes up oil
in a manner similar to capillary action.

"Capillary action" is a phenomenon in which liquid is naturally drawn into a thin tube placed in liquid.

Mosquito legs, with their fine ridged structures, are also very thin,

and in the case of an oil, with its attractive properties, the liquid is drawn in.

But that's not all!

When the hydrophobic legs contact the oil,
it can generate a pulling force.

Let's place an actual mosquito leg in the silicone oil and see what happens.

Look closely at where the arrow is pointing.

The oil is drawn up into the leg!

When this happens, surface tension forms what's known as a meniscus.

The meniscus is what generates the pulling force on the mosquito's legs.

When this happens, the resulting force has been measured at 5 Micronewtons.

To humans the force is imperceptible,

but mosquitoes feel it as very strong.

Testing a variety of liquid ingredients, they've developed an original oil.

Already available in Thailand, it's now saving lives;

all thanks the unique insight and technology of a cosmetics manufacturer.

This is quite interesting.

The careful study of mosquitoes allows development of mosquito repellants

that are friendly to humans, and mosquitoes too.

Mosquitoes are hated, but they're also living things, treasure-troves of various biological phenomena.

And careful study out of scientific curiosity can lead to such applications.

This is one of the attractions of mosquito research.

By the way, Tina, when you get bitten by a mosquito do notice it?

Not really.

It's when it starts itching, that's when I know I've been bitten.

You're not alone.

Surprisingly, many people don't actually feel the bite.

This is due to a rather "high-tech" feature of the mosquito.

It's a discovery likely to have real-world benefits too,

as work making use of it is already underway.

A researcher is working to mimic the structure of a mosquito's mouth,

or proboscis, to create a painless hypodermic needle.

I was interested in why mosquitoes
are able bite without causing pain.

Using the latest engineering methods,
we're developing products to benefit everyone.

One of the reasons why mosquito bites don't hurt is their ultra-thin "needle," the proboscis.

Compared to an ordinary syringe used for drawing blood, the difference is clear.

The part that actually resembles a needle is at the tip of the proboscis.

Hidden inside is a needle with a most amazing structure.

In fact, it's made up of six distinct needle-like elements.

Kansai University's Dr. Seiji Aoyagi has clarified the precise mechanism of each one.

The outer pair are serrated like a saw to cut open the skin.

Next, #2 is a hollow tube used to inject mosquito saliva that prevents the blood from clotting.

Then, #4 is the main needle that draws blood from the capillaries.

Once finished drawing blood, #3 and #5 close off the main needle to prevent leakage.

The key is the serrated parts.

Without deforming the skin,

they make it possible to minimize the stimulation of nearby pain receptors.

Additionally, Dr. Aoyagi's latest research

has shown that rotation of the proboscis needles is another factor in reducing pain.

A plastic needle based on the mosquito's...

...tried out on a sheet of silicone rubber that simulates human skin.

First, piercing the sheet with an ordinary, non-rotating needle...

...you can see that it deforms.

But using the rotating needle...

It's been found that rotating needles reduce skin resistance as well as pain.

I think it'll have multiple applications.
Firstly, for children and infants.

And also for adults who,
although better able to handle pain,

require multiple daily injections
such as patients with diabetes.

They'll be the main beneficiaries.

Research is also underway to apply another of the mosquito's distinctive characteristics for use in flying drones.

This research is being done by a real insect lover...

Dr. Toshiyuki Nakata of Chiba University.

I love insects. I have since childhood.

My relatives all expected me
to become an entomologist.

I truly love the work I do.

How do insects fly? Nakata's research involved these flight mechanisms.

One day, he was approached by a specialist studying the sounds mosquitoes make.

We decided to look into how they
fly in the dark without hitting things,

bumping into the walls or the floor.

When I heard they could use sound
to find obstacles, I couldn't believe it.

The key is a special organ at the base of the mosquito's antennae, "Johnston's organ."

Mosquito antennae receive sound and vibration, playing a role similar to the human eardrum.

The so-called, "Johnston's organ" at the base senses antennae vibrations.

What's most astounding is its sensitivity.

It's been reported to respond to even the slightest vibrations in air,

an antennae deflection of just 0.0005 degrees.

This caused Nakata to wonder if mosquitoes could sense the vibrations created by their own wings.

First, by analyzing the flapping motion of the wings with a high-speed camera,

they found it was extremely fast, about 600 to 800 times per second.

They also calculated the air currents generated by mosquitoes' wings

and investigated the airflow around obstacles such as walls and floors.

As a result, they discovered that Johnston's organ can detect air fluctuations from up to 3cm away,

an astounding ten times the body length of the mosquito.

This meant that sensing obstacles like walls or floors was indeed possible.

And when compared to humans...?

At human scale it would be like using
the airflow from flapping your arms

to detect a floor that was
4 or 5 stories below you.

Development of drones applying the research done by Nakata is now being done abroad.

This drone senses the air currents it creates.

When the airflow is disturbed it glows red, recognizing obstacles and avoiding them.

Nakata says that drones like these have a variety of possible uses.

In the case of a disaster, when
flying in complex surroundings,

or through trees in nature,
detecting and avoiding obstacles.

It's extremely important technology,
and I believe it can be used for this.

I must say, I'm quite impressed with the physical structure and abilities of the mosquito!

As we reveal more and more of the hidden powers of the mosquito,

it would seem that the diseases they carry are the real villains in the story.

We might hope, someday, they'll be gone for good.

Next, today's Takumi is an innovator who, aware of the critical situation of the world's fisheries,

came up with a way to make "something" from "nothing," at least in terms of environmental impact.

We look at a distinctive food product made by feeding food waste to microalgae living in the sea.

We have come to a restaurant in Shinjuku, Tokyo, that specializes in vegetable dishes.

Hi, I'm Michelle.

Today, I'm at a restaurant that uses a very special ingredient.

I wonder what he's preparing for me right now.

Here's the dish.

Enjoy!

A potato pancake.

But we're really here for the yellow powder.

Okay, so let's taste this ingredient!

I know this taste. It's very... "seafood."

Is this powder made using fish?

This is algae from the ocean.

Algae?

Yes, it's a new seasoning
made from dried algae.

Algae that lives in the sea!

Because it is plant-based, but has the flavor of seafood, it's an innovative seasoning for vegans.

Originally, this seasoning was not developed for human consumption!

It's made in Uruma, the third largest city in Okinawa.

At this facility, the Okinawan government supports entrepreneurs conducting health and biotech related research.

A venture company here has developed the algae seasoning.

The company president, Takada Daiichi, is the innovator.

Takada was conducting research on algae to produce feed for aquaculture.

It's hard to see, but these
white streaks are algae seeds.

When first put it on the petri-dish,
you can barely see anything.

But as it grows, it turns white.

Takada turned to a type of microalgae, called Aurantiochytrium, to produce fish feed.

This is because this particular algae efficiently produces Docosahexanoic acid or DHA.

DHA is an omega-3 fatty acid,

and is abundant in the fat of blue fish such as tuna and bonito.

DHA is essential for human brain and nerve development.

It's also essential for fish growth.

Fish feed on microalgae, which can synthesize DHA.

The DHA accumulates in the fish through the food chain.

Takada decided to cultivate the algae to create a totally new fish feed.

5 years ago, Takada was working for a major trading company in Tokyo.

The beginning of his involvement in fish farming, was as a new business.

Farmed fish basically grow
by eating fish, natural fish.

This is because they need supplementary
protein and DHA.

So, in the fish farming industry,
the fish also grow by eating fish.

However, there was a challenge.

Unlike other algae, which grow on only light and water,

aurantiochytrium cannot produce DHA without being fed organic "food."

Therefore, the cost of this "food" must be reduced to make the end product marketable.

So, they focused on food waste as food for the algae.

We wanted to utilize unused resources.

Things like the lees left over
from making sake or shochu.

We try to use food waste
sourced from businesses.

As he experimented, he was shocked by the results from a particular "food" source.

It's... lees from Awamori, a type of Okinawan liquor.

Awamori lees are the dregs left over from the distillation of Awamori.

Awamori is made using "black yeast malt."

And this yeast, is believed to have originated in Okinawa.

In fermentation, black yeast malt produces large amounts of citric acid,

so Awamori lees are rich in it.

This was an unexpected blessing.

Citric acid transforms into different acids and then back into citric acid.

This is called the "citric acid cycle."

Citric acid creates succinic acid.

This is a flavor component found in scallops and clams.

Takata and his team believe that this created a "flavor of the sea" that they had not initially expected.

This led to the creation of algae that can be consumed not only as a fish feed,

but also directly by humans as a source of DHA.

The local sake brewer also appreciated the use of Awamori lees,

which would otherwise have been discarded.

If we had to dispose of them
it would be very costly.

But if they could be used effectively,
it would really help our industry.

Takada's goal is to make the way we the ocean more sustainable.

And he continues to work toward reducing costs

to make his product suitable as fish feed, its original purpose.

Our generation has to move
toward greater sustainability.

I want to use our company's
technology for new aquaculture

in which fish are not fed to fish.