Far more lethal than sharks, wolves, bears, or any other fanged beast is the tiny mosquito, which holds the title of world’s deadliest animal. The World Health Organization estimates that “millions” of people die every year from mosquito-borne diseases. Thankfully, scientists have come up with a strategy to greatly reduce the mosquito population, but it requires sending tens or even hundreds of thousands of mosquitoes to different areas of the world, often through the mail.
You might assume that you’d need a rather large package to ship these thousands of mosquitoes. But a new study has found you can actually compress these pests into a ridiculously tiny space, and they’ll stay alive. They’ll even survive the trip better than mosquitoes packed loosely.
How tiny? Well, according to the researchers behind the new study, published Wednesday in the Journal of Insect Science, the magic number is somewhere around 240 mosquitoes per every cubic centimeter. That amounts to around 1,200 mosquitos in a single teaspoon, and up to 2,500 in a 10-milliliter syringe. Another way to picture it: That’s 7,200 living mosquitoes packed into a 1-ounce shot glass.
The team, led by researchers from New Mexico State University, came to this calculation after conducting a series of lab and real-world experiments, including sending the insects through overnight mail. They were hoping to figure out the best way to use these pesky bloodsuckers to save lives.
In the 1950s, scientists devised a clever way to eradicate dangerous insects without using pesticides, called the sterile insect technique. You basically breed a giant population of male insects in the lab, and sterilize them without harming them otherwise. Then, you release them into the wild, hoping that they’ll breed with the females. Over time, as the intact males are crowded out of the mating game and the females lay eggs that never reach maturity, the whole population dwindles.
The first insect this was tried with, to great success, was the screwworm fly. Since then, the technique has been used to eradicate populations of various fruit flies and moths. And nowadays, researchers, including the scientists behind this latest study, are eagerly beginning to test out whether it can work for the deadliest animal around, the mosquito.
But according to senior researcher Immo Hansen, using the technique on mosquitos poses more of a logistical hurdle than it did for the screwworm fly.
“Male mosquitoes are really lazy. They don’t like to fly much,” Hansen told Gizmodo. “Over a lifetime, they’ll fly up to 100 meters, 200 meters, but not more.”
Because of that laziness, eradication campaigns will need to get the sterile mosquitoes as close to the action as possible. Using aerial drones might help, but we’ll still need to make sure that they’re stored, packaged, and released safely, without accidentally killing or maiming them.
So Hansen and his team conducted experiments in the lab, hoping to find the ideal shipping conditions for the mosquitoes. They tested a variety of temperatures to keep the insects sluggish. They also tested how tightly they could pack mosquitoes into various syringe sizes. Then they took things one step further and mailed thousands of bugs from New Mexico to their colleagues over at the University of California, Davis.
The mosquitoes were generally fine with being kept chilled at a wide range of temperatures, though 57.2 degrees Fahrenheit (14 degrees Celsius) appeared to be ideal. And in the lab, it initially didn’t seem like there was any major difference in the survival rate when it came to how tightly packed they were. But things changed in the live test.
“It turns out that the highly compacted mosquitoes survived the trip better than the loosely packed ones did,” said Hansen. “We think this is because the vibrations of the plane damaged the loosely packed mosquitoes.”
The team next plans to test out their theory that vibrations cause more deaths in the loosely packed groups. They also hope to conduct live trials of shipped mosquitoes to ensure that the cramped arrangements aren’t cramping the mosquitoes’ mating prowess.
“We’re going to work with our physical science lab here at New Mexico State, since they have vibration tables they use to make electronics vibration-proof,” Hansen said.
And if you’re wondering, yes, it’s quite legal to send mosquitoes (and other bugs) through the U.S. Postal Service, so long as you follow their rules.