Scotland

Why a Scottish lab is breeding mosquitoes

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Media captionThe Centre for Virus Research is breeding thousands of mosquitoes every week

You might think Scotland has enough to contend with, after all we already have midges, but a research centre in Glasgow is now breeding thousands of tropical mosquitoes every week.

It is part of the fight against viruses which are destructive and deadly to humans and livestock.

The Medical Research Council-University of Glasgow Centre for Virus Research (CVR) is trying to stop further epidemics of diseases such as Zika, Dengue and yellow fever.

In what is the world's largest group of human and veterinary virologists under one roof, they're looking at the problem for every level, from molecules up to entire ecosystems.

It's at the latter level that the mosquitoes come in. Or rather where I come in to where the mosquitoes are.

Image caption Dr Emilie Pondeville works inside the insectary

Through an airlock at the CVR in the west of Glasgow lies the insectary.

Inside it's hot - as you would expect from a facility that houses thousands of tropical life forms.

It's dinner time and Dr Emilie Pondeville is offering a menu which may lack variety but still hits the spot.

Small, circular capsules containing rabbit blood.

Image caption The mosquitoes bite through the artificial membrane to feed

She says: "There's an artificial membrane and these capsules are then screwed onto this unit, which is basically just a heater to mimic our body temperature.

"Then we put this blood capsule on top of the cage."

The cage being a plastic cube with a net lid. The mesh has holes just large enough for the female mosquitoes to poke their proboscises out and puncture the membrane.

In other words, they're biting.

We bend down to watch the insects feed.

Global effort

Each female's meal may only be a couple of micolitres or thereabouts, but that is two to three times their body weight in blood.

If these ladies were carrying a virus - which for safety reasons they're not - it would be passed in the other direction.

In an ideal world there'd be a vaccine for every virus.

The team at the CVR are part of the global effort to create as many as possible.

But some viruses have proved stubbornly resistant to this approach.

Image caption Dr Claire Donald says it is vital to study the insects that carry the disease

That is why the CVR's Dr Claire Donald says it is also vital to study the insects which are the vectors along which the diseases travel.

She says: "There's a huge number of mosquito-transmitted viruses out there.

"The major ones being Zika, yellow fever as well - you also have things like dengue which affect millions of people all over the world.

"The mosquitoes that spread these diseases can be found in places like Greece, Italy and Spain.

"So it's very important that people are aware of this when they go on holiday. It's not specifically tropical areas or Africa where they could in contact with these infections.

"It's on our doorstep."

And these are just the threats we know of.

Image caption Prof Alain Kohl is trying to identify the next epidemic

In his laboratory, Prof Alain Kohl is trying to anticipate which viruses may be lurking at a low level before becoming full-blown epidemics like Ebola and Zika.

"Zika virus is a classic example of what could happen," he says.

"We have discussions over this very frequently.

"It may be the next Zika virus is already a virus that is in a list somewhere, a name that we have heard in the past.

"But it could also be a virus that we don't expect."

That is another reason why the CVR is investigating the vectors as well as the diseases.

The thriving mosquito population is soon to be joined by other life forms which are even less pleasant, if that is possible: ticks.

Image caption Dr Benjamin Brennan tips a tick into a Petri dish

Dr Benjamin Brennan tips some out into a Petri dish for me.

Happily these ones are quite dead, preserved after being removed from the back of an unfortunate hedgehog on South Uist.

Most are tiny pupae but one is bloated, evidence that it enjoyed a slap-up final meal.

Ticks matter to Dr Brennan because they are bringing diseases even closer to home.

He says: "Tick-borne encephalitis is present in Germany and the Netherlands at the moment.

"We've seen the recent emergence of a very severe disease called Crimean-Congo Haemorrhagic Fever in Spain.

"People have actually contracted the disease locally from ticks."

Grudging respect

Back downstairs in the insectary, the mosquitoes are very much alive.

There is a slim chance of being bitten but these mosquitoes are not carrying any viruses.

Dr Pondeville admits that when she began her work she had a phobia of insects. But now she loves mosquitoes.

I wouldn't go that far, but even a short time in their company does produce a grudging respect for their many, almost endearing, characteristics.

Their perfectly proportioned proboscises, just right for getting through your hide and into your blood. (Unlike the Scottish midge which tears a lump out of your skin.)

The rapidly wriggling larvae whose favourite snack - in here at least - is cat food.

The fact that female mosquitoes are monogamous, which may provide a means of us attacking them.

If the male with which they mate just that once has been genetically engineered to be sterile, there will be no future generations to bite us.

Of course there is a catch: wiping them all out would be dangerous.

Mosquitoes have their place in the larger ecosystem. They cannot be removed completely without damaging the whole.

Their immune systems open up more possibilities though.

Why do they not suffer from the viruses they carry - and might it be possible to turn their immune systems against them? It's been achieved in the laboratory but not yet in the field.

That is one reason why the CVR will continue to breed as many as 10,000 mosquitoes every week.

They are treated well. The females get their blood, the males are happy with a sugar solution.

But what happens after each generation has outlived its usefulness? There it seems the hospitality stops.

Let's put it this way: they are neither released into the wild nor found caring homes.

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