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Perspective | There Will Be Blood: Inside the US Army’s Mosquito Breeding Program

Perspective |  There Will Be Blood: Inside the US Army’s Mosquito Breeding Program

It’s always a muggy Washington summer inside the U.S. Army Insectarium, the nursery where researchers grow mosquitoes from eggs to adults. The temperature remains at 82 degrees, with a humidity level that borders on swampy.

About 10,000 mosquitoes a week breed at the Walter Reed Army Research Institute, on the edge of a light industrial park in Silver Spring. I started to feel itchy a few minutes after entering the insectarium, a room the size of my dining room. I hadn’t been bitten, but I had trouble convincing my brain of that.

The military worries about mosquitoes because every soldier affected by an insect-borne disease (malaria, Zika, viral encephalitis) is a soldier who cannot go into battle. The work done at WRAIR has helped develop vaccines and insect repellents.

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“We call it maintaining combat strength,” he said. Lieutenant Colonel Elizabeth Wanjadirector of the entomology branch of WRAIR.

To understand how mosquitoes transmit diseases (and to develop and test vaccines against those diseases) a reliable supply of mosquitoes is needed. WRAIR currently breeds six species, including Aedes aegypti, Aedes albopictusthree types of Anopheles and Culex.

Along one wall of the brightly lit insectarium are shelves holding large shallow containers, each holding a few centimeters of water. Small mosquito eggs are added to the water (they reminded me of ground black pepper). The eggs hatch and become larvae. The larvae are fed fish food, then removed and placed in white plastic buckets on shelves on the opposite wall. There, under a fine mesh screen, they become pupae, which is a kind of tadpole stage of the mosquito.

When I moved my hand over a cube, the hundreds of tiny black commas floating inside rippled as one, like a murmuration of starlings.

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“We call those tumblers,” Wanja said of the pupae that had been surprised by my shadow. It was one of the creepiest things I’ve ever seen in my life.

It takes about a week to go from egg to adult.

If you’re studying mosquito-borne diseases, all you want are female mosquitoes, which need a blood meal to lay eggs. Females are more attracted to heat (the better to find a live animal to bite), so to separate the sexes, an insectarium holds a heat source against the bucket.

And to feed them? Donated human blood is placed in a small glass vessel sealed with a membrane. Pushing the membrane against the mesh is like ringing the dinner bell. The mosquitoes get up and start drinking.

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When you buy eggs at the supermarket, you get a dozen per box. When you get mosquitoes from the insectarium, you get 250 per bucket. Feeding them malaria-infected blood allows researchers to test vaccines on volunteers.

How do you enter the world of mosquitoes? Tobin Rowland He is the head of the insectarium. His first duty assignment after enlisting in the Army in 2003 as a medical laboratory technician was inside the WRAIR Insectarium.

“I just fell in love with it,” said Rowland, now a civilian.

Wanja grew up in Kenya, where as a child she was fascinated by insects. She was earning her doctorate in entomology in 1998 when terrorists blew up the U.S. embassy in Nairobi. Some of her relatives were among those killed. Wanja wondered how she could employ her skills against the terrorists. Fighting mosquitoes was her response.

“It was one of the ways I was able to come in and work to support the military and be able to get rid of these guys,” he said.

In 2007 and 2008, Wanja spent 15 months in Iraq studying insects and how to combat them.

How do people react when Wanja and Rowland explain their work?

“I think the most common answer is, ‘Do you make a living playing with insects?’ That’s not work,’” Rowland said. “Most people don’t really understand the threat associated with insects.”

And not just because of the mosquitoes. The insectarium also breeds sandflies, which bite even worse than mosquitoes. Sandflies feed in “pools.” Instead of piercing the skin with a hypodermic needle-like proboscis, they use their mouthparts to cut through the tissue, feeding on blood that bubbles to the surface. In the process, they can transmit leishmaniasis and sandfly fever.

Global warming appears to be expanding the territory of tropical diseases. And a new threat is on the horizon.

“Ticks are starting to become the main problem,” says Wanja. “We’re finding pathogens we didn’t know about in ticks.”

That means WRAIR will need to study them. Soon, the tapping of tiny tick feet will reach the insectary.



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