Scientists at a U.S.-funded facility in Panama are preparing to launch the first outdoor tests of genetically modified screwworm flies, a move aimed at strengthening the campaign against a flesh-eating parasite that has spread through Central America and into the United States. The work will happen inside mesh cages, where researchers will expose the flies to Panama's heat and humidity to see how long they survive outside laboratory conditions before any later field testing begins.
The people at the bottom of this mess are livestock producers, and the parasite is already on their land. Wild screwworm flies spread throughout Mexico and, in June, infested livestock on Texas farms for the first time in decades. Reuters said widespread infestations could cause estimated losses of more than $1 billion to Texas' livestock industry and spread to other U.S. states. That’s the hierarchy in plain view: decisions made in federal offices and research labs, while the costs land on farms, animals and workers.
Who Runs the Operation
The U.S. Department of Agriculture and Panama's Ministry of Agricultural Development jointly manage and finance the plant, which produces about 100 million sterile flies per week. Opened in 2006 on the narrow isthmus, the plant was intended to maintain a barrier to stop wild screwworm flies from moving north into Central America and North America. Now that barrier looks thin. With cases spread over a large area, the sterile flies produced in Panama are not nearly enough to eradicate the parasite. Experts said they need 500 million a week to push screwworm flies back to the geographic boundary of the Darien Gap, the stretch of rainforest between Panama and Colombia.
The Trump administration has touted the genetically modified fly, called NovoFly, as a game-changer in the fight against New World screwworm. The pitch is classic top-down management: a new engineered organism, a new promise, and the same old faith that centralized control can patch over a problem created by industrial agriculture and border-spanning supply chains. NovoFly is genetically engineered to produce only males. Once the male offspring are sterilized, they could be released to mate with wild female screwworm flies, which then lay unfertilized eggs. Wild female screwworm flies normally mate only once, so sterile male flies can make the population progressively decline until it is eradicated.
The USDA started using the technique in 1957 to fight the pest, which was eradicated from the United States in 1966, and later used it to eliminate other outbreaks. The Panama facility currently produces males and females, and the females are useless in controlling the wild population, but there's no easy way to separate them, according to the USDA and entomologists. NovoFly is designed to boost the production of sterile flies by cutting out that waste.
What the Labs Say
Scott Hutchins, USDA's chief scientist and an undersecretary, said at a news conference in June, "It's going to allow us to almost instantaneously double the number of sterile flies that we put in the fight," and, "It's going to give us a tremendous edge." Rear Admiral Michael Schmoyer, who is leading USDA's efforts against screwworm, said at a legislative hearing in Texas, "The last thing we'd want to do is rush a process to be able to have what's called a total brood collapse," and, "You start with zero, and then you have to build up again."
The USDA conducts some of its screwworm research at the Knipling-Bushland U.S. Livestock Insects Research Laboratory in Kerrville, Texas, a facility named after American entomologists who developed the process to sterilize screwworm flies. The flies are blasted with radiation before release, a process that would also be used on NovoFly. Officials at the Kerrville lab said scientists were expecting approval soon from Panama's biosecurity agency to begin NovoFly tests outdoors at the Panama lab. The Panama-United States Commission for the Eradication and Prevention of Screwworm, which operates the Panama plant, deferred requests for information to the USDA, and the Panamanian Food Agency declined to comment.
After the initial tests in Panama, larger field trials on NovoFly are expected to begin at a ranch nearby in nine to 12 weeks, when researchers will release 50,000 of the insects every few days, said Alex Arp, a USDA research geneticist working in Panama. The flies will be marked with fluorescent dyes visible under black light, and traps around the ranch will allow researchers to track how long each release survives. Maxwell Scott, an entomologist at North Carolina State University who helped develop NovoFly, said field tests typically run for about six to eight weeks and warned, "We may get out in the field, and it may not fly very well."
If NovoFly performs well in trials, it would take time to scale up production. Experts said it may be less risky to produce it at a new sterile-fly production facility expected to open in Texas late next year rather than initially in Panama. Adding NovoFly to the Panama facility could risk disrupting the largest source of sterile flies and cause a collapse of production if scientists fail to establish the correct diets, temperatures and conditions for the new strain. That’s the fragility of the whole setup: one bad adjustment, and the machine that’s supposed to hold the line can stumble.
The U.S. Environmental Protection Agency published a proposed decision to register NovoFly in June, according to the USDA. If fully approved, NovoFly would become the first genetically modified insect to get full EPA clearance, Scott said. Mexico supports using the male-only flies and could be producing them by the end of the year at a newly reopened production plant, said Gabriel Ayala, head of animal health for Mexico's National Service for Agri-Food Health, Safety and Quality. Eventually, they could be produced in Panama, Mexico and at the planned U.S. plant in Texas, he said.
Edwin Burgess, an assistant professor of veterinary entomology at the University of Florida who is not involved in the project, said even a modest increase in the number of sterilized males could lead to a quicker eradication of wild screwworm flies. He said researchers need to make sure NovoFly is competitive against wild male screwworm flies for mating and can be reared successfully on a large scale. Burgess said, "There are still a lot of things that need to be done to get that technology to where it needs to be. But it's certainly very, very promising."
Kim Lohmeyer, Kerrville lab director, said she hopes the U.S. can eradicate screwworms much faster than the decades it took before the pests were controlled in the 1960s. But even if the NovoFly trials succeed and it is brought into production, it will likely take more than a year to control the pest, she said. "It will take some time and effort," she said. "We need more flies."