It’s Loose!


Tom Easton


What’s loose?

If you’re a fan of old movies, you are probably thinking Giant BUGS! Ants! Moths! Lizards! Squids! Things from the swamp! And of course those velociraptors from Jurassic Park.

You’re partly right. Bugs, but not giants. Genetically engineered bugs, with features Mother Nature never dreamed of, unless she was having a bad night.

To be more precise, mosquitoes genetically engineered to make their offspring either sterile or dead. (Ma Nature wouldn’t dream of that because Her whole point is reproduction.)

Why would the genetic engineers want to do that? Well, for one thing, mosquitoes are the deadliest animals on the planet (other than us). They spread diseases—malaria, yellow fever, dengue, Zika, West Nile, chikungunya. And the genetic engineers have said to themselves, “We can stop that.”

They’re not trying to do something really, really cool like bringing Tyrannosaurus rex back from extinction. (But hold that thought.) They’re trying to be useful, and in a big way.

Aren’t there other ways to solve the problem? Vaccines, maybe? We only have one for yellow fever so far. Insecticides? Unfortunately, insecticides create more problems than they solve. They kill a great many insects—predators, bees, butterflies—besides the ones you’re after. They are also toxic to humans and other animals.  And natural selection ensures that insect populations become resistant to insecticides, so the chemical approach never works for long.

The sterile male technique was devised in the 1950s to control the screwworm fly, which lays its eggs in open sores on the hides of cattle and can kill cattle within 10 days. It involves raising large numbers of bugs in the lab, exposing them to radiation to sterilize the males, and releasing them wherever there is a screwworm problem. Many or most wild females mate with a sterile male, and—since they mate just once and store the sperm—their eggs are then duds. The population crashes. This is how the screwworm was eliminated as a problem in North America and Africa. The technique has also been applied to other insects such as the Mediterranean fruit fly and mosquito, though with less dramatic success because the females mate more than once.

The World Mosquito Program (, is working intensively on using a bacterial symbiote, Wohlbachia, which research shows can reduce the ability of mosquitoes to pass on dengue, chikungunya, malaria, and yellow fever. They propose to release Wohlbachia-infected mosquitoes in disease-prone areas and have already done so in Australia and Miami; results are encouraging.

There are several approaches to using genetic engineering to attack the problem. One modifies specific genes to make male mosquitoes sterile (instead of exposing them to radiation).  A second approach, introduces new genes to make offspring die before they can mature and transmit disease. A third approach fiddles genes to make almost all offspring male. All three aim to reduce reproduction of mosquitoes in an area so that their numbers and disease transmission both decline.  A fourth approach aims to make mosquitoes less able to carry and spread disease.

Of course there is opposition. The anti-genetic engineering folks think it’s unnatural, it infringes the genetic integrity of species, and who knows what awful things will happen if the engineered genes get into other critters, like maybe even people! Adrienne LaFrance, “Genetically Modified Mosquitoes: What Could Possibly Go Wrong?” Atlantic (April 26, 2016), recognizes the need to control mosquito populations and notes that many objections to genetic engineering are rooted in misinformation. In other words, no, genes that sterilize mosquitoes won’t sterilize people, or hummingbirds (which do eat mosquitoes). Fear of disease, she says, is likely to mean genetically engineered mosquitoes will eventually be widely released into the environment.

So far, most genetically engineered mosquitoes have been tested only in laboratory cages.  However, the British company Oxitec has released genetically engineered male mosquitoes whose offspring die. They have reported success in the Cayman Islands in the Caribbean (2009) and in Brazil (2013). Activists are trying hard to prevent approval; see Food and Water Watch’s call for the FDA to say no at “Advocates Urge FDA to Halt Risky GMO Mosquito Release” ( ).  But the opposition is not succeeding; see Megan Molteni, “How Self-Limiting Mosquitoes Can Help Eliminate Malaria,” Wired (June 21, 2018)(

It’s only a matter of time before these mosquitoes are released wherever mosquito-borne diseases are a problem. Eventually, we might even release them where the only problem is itchy mosquito bites.

And if mosquitoes go extinct? Their larvae are fish food, and they themselves are bird food. But nothing (as far as we know) eats nothing but mosquitoes and is in danger of extinction if we do away with the bugs.


Coming soon… Maybe…


Genetic engineers are also working on pigs that don’t carry the remnants of ancient retroviruses. If they succeed, people who need organ transplants could get them from pigs instead of motorcyclists who don’t wear helmets. They’re also working on cattle that produce beef more efficiently and lambs that are meatier. If they succeed, the big question will become whether people will accept the fruits of their work.

A little further down the road is genetic engineering to bring the mammoths back. The engineers know the recipe, for they have DNA samples. What they need to do is edit elephant DNA to match mammoth DNA. If successful, they can then release mammoths into the North American wild, where their grazing may help the land store more carbon and thus fight climate change. For three links to the topic, try these:


If you’re interested in recreating an ancient ecosystem, you also need predators such as dire wolves (, though they apparently preyed on horses more than mammoths.  We may not need genetic engineering to bring them back, however.  Dog breeder Lois Schwarz is trying to “breed back” from dogs and wolves to get something that at least looks like a dire wolf; she is the founder of the Dire Wolf Project ( If she succeeds, the genetic engineers might need to make just a few tweaks to add in an appropriate level of ferocity.

Nothing could possibly go wrong, right?

It would surely be safer to bring back the passenger pigeon, and in fact there is a Great Passenger Pigeon Comeback Project ( that will require a good deal of genetic engineering.

But if you want to do birds—and the passenger pigeon really is an excellent choice for we have tissue samples and it’s a conservation icon—how about the terror birds ( The Florida version, Titanis walleri, reached North America about 5 million years ago and lasted for nearly four million years. It stood about 7 feet tall, weighed over 300 pounds, had a beak the size of a suitcase, and was a thoroughly impressive predator ( ). DNA has been recovered from fossil eggshells, but Google finds no trace of revival projects.

Perhaps that is just as well. It probably wouldn’t have much interest in your birdfeeder. Even your German shepherd would be but a snack. It would find more satisfaction at the Costco meat department. Or maybe the checkout line or parking lot.

Still… We do have some DNA. If we can do mammoths and passenger pigeons and tweak dire wolves, we can probably do terror birds in a decade or so. However, I can just imagine the cries of horror from the anti-genetic engineering folks. Not just unnatural! And genetic integrity! But also WE’RE ALL GONNA DIE!!

Sounds like Jurassic Park, doesn’t it? That’s not possible since we don’t have dinosaur DNA to play with. But a park with mammoths and dire wolves and terror birds would be possible. We could even turn them loose on the landscape.


Human beings are the most dangerous creatures on the planet (after the skeeters). We could probably change the minds of at least some of the anti-genetic engineering folks just by saying “hunting.”

Just imagine a game park with terror birds!

“Hold my beer, will you? I’ve got that!”


And now that I’ve offended the anti-hunting folks, I’ll stop.










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