Scientists at a U.S.-funded facility in Panama are preparing the first outdoor tests of genetically modified screwworm flies, a direct intervention to protect the livestock industry from estimated losses exceeding $1 billion. This move comes as the flesh-eating parasite has spread through Central America and into U.S. states, threatening accumulated capital in the agricultural sector. Researchers will confine the flies in mesh cages, exposing them to Panama's climate to gauge their survival outside controlled laboratory conditions before advancing to larger field trials.
The Trump administration previously championed NovoFly, the genetically modified fly, as a transformative tool against the New World screwworm. These parasitic flies lay eggs in warm-blooded animals' wounds, with larvae burrowing through living flesh, often killing the host if untreated. Reuters reported that widespread infestations could inflict over $1 billion in losses on Texas' livestock industry alone, with potential to spread further into other U.S. states.
For decades, the primary defense has been the release of sterile screwworm flies, largely produced at the Panama facility. This plant, jointly managed and financed by the U.S. Department of Agriculture (USDA) and Panama's Ministry of Agricultural Development, produces approximately 100 million sterile flies each week. Opened 20 years ago in 2006, its original purpose was to form a barrier, preventing wild screwworm flies from advancing north into Central and North America.
Protecting Capital's Interests
Wild screwworm flies have now breached this barrier, spreading throughout Mexico and, just 1 month ago in June, infesting livestock on Texas farms for the first time in decades. The current output of sterile flies from Panama is grossly inadequate to eradicate the parasite across such a vast affected area. Experts estimate a need for 500 million sterile flies weekly to push the screwworm population back to the Darien Gap, the natural rainforest boundary between Panama and Colombia.
NovoFly is engineered to produce only male offspring. Once these males are sterilized, they would be released to mate with wild female screwworm flies, which typically mate only once. This process would lead to the laying of unfertilized eggs, causing a progressive decline in the wild population until its eradication. The USDA first employed this sterile insect technique 69 years ago in 1957, successfully eradicating the pest from the United States 60 years ago in 1966, and later using it to suppress other outbreaks.
The NovoFly project aims to significantly boost sterile fly production. The Panama facility currently produces both males and females, but females are ineffective in controlling wild populations and are difficult to separate, according to the USDA and entomologists. Scott Hutchins, USDA's chief scientist and an undersecretary, stated 1 month ago in June that NovoFly "is going to allow us to almost instantaneously double the number of sterile flies that we put in the fight," promising "a tremendous edge."
The Limits of Technology
Some screwworm research is conducted at the Knipling-Bushland U.S. Livestock Insects Research Laboratory in Kerrville, Texas, named after the entomologists who developed the sterilization process. Flies are blasted with radiation before release, a method that would also apply to NovoFly. Officials at the Kerrville lab anticipate imminent approval from Panama's biosecurity agency for the outdoor tests at the Panama lab. The Panama-United States Commission for the Eradication and Prevention of Screwworm, which operates the Panama plant, directed inquiries to the USDA, while the Panamanian Food Agency declined comment.
Following initial tests in Panama, larger field trials are slated to commence at a nearby ranch in nine to 12 weeks. Alex Arp, a USDA research geneticist in Panama, indicated that researchers would release 50,000 insects every few days. These flies will be marked with fluorescent dyes, allowing researchers to track their survival via traps around the ranch.
Maxwell Scott, an entomologist at North Carolina State University who contributed to NovoFly's development, cautioned that field tests typically last six to eight weeks and warned, "We may get out in the field, and it may not fly very well." Even if NovoFly performs well in trials, scaling up production will take time. Experts suggest it might be less risky to produce the new strain at a sterile-fly production facility expected to open in Texas late next year, rather than initially integrating it into the Panama facility. Adding NovoFly to the existing Panama operation could risk disrupting the largest source of sterile flies and potentially cause a "total brood collapse" if the correct diets, temperatures, and conditions for the new strain aren't established.
Rear Admiral Michael Schmoyer, leading USDA's screwworm efforts, emphasized at a Texas legislative hearing, "The last thing we'd want to do is rush a process to be able to have what's called a total brood collapse." He added, "You start with zero, and then you have to build up again."
State-Backed Solutions
The U.S. Environmental Protection Agency (EPA) published a proposed decision to register NovoFly 1 month ago in June, according to the USDA. If fully approved, NovoFly would become the first genetically modified insect to receive full EPA clearance, Scott confirmed. Edwin Burgess, an assistant professor of veterinary entomology at the University of Florida not involved in the project, noted that even a modest increase in sterilized males could accelerate eradication. He stressed the need to ensure NovoFly's competitiveness against wild males for mating and its successful rearing on a large scale. Burgess stated, "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."
Mexico supports the use of male-only flies and could begin production by the end of the year at a newly reopened plant, according to Gabriel Ayala, head of animal health for Mexico's National Service for Agri-Food Health, Safety and Quality. Eventually, production could expand to Panama, Mexico, and the planned U.S. plant in Texas. Kim Lohmeyer, Kerrville lab director, expressed hope for a faster eradication than the decades it took to control pests in the 1960s. However, she acknowledged that even with successful NovoFly trials and production, it will likely take more than a year to control the pest. "It will take some time and effort," she said. "We need more flies."