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Nature writes the best horror stories – In The New York Times’ recent piece, the return of the screwworm, a flesh‑eating parasite once eradicated from the U.S. Indeed, cattle ranchers are once again staring at wounds riddled with maggots. This insect, which devastated cattle in the 20th century, is making a comeback, spurring governments to resurrect old strategies and also explore new biotech tools.
The system deployed against screwworm back then was the sterile insect technique (SIT). SIT consisted of releasing radiation‑sterilized males massively to mate with wild females. Because a female screwworm mates only once, those unions produced no offspring, and over time, the population collapsed. The technique was a success, eradicating the pest from the U.S. by the mid‑1960s.
But now, with screwworms advancing north from Mexico and Central America, authorities are combining that classic method with modern biotech solutions. Planning is already underway for a new $ 750 million sterile‑fly factory in Texas with a projected production of 300 million sterilized screwworm flies per week. At the same time, the U.S. Department of Agriculture (DA) invested another $100 million in alternative technologies, while research into gene editing and synthetic lures seeks to add nimble, next‑gen tools to the eradication toolbox.
In this article, we take a look at what biotech is allowing in the field.
Table of contents
The screwworm in cattle: Old enemy, new biotech
The SIT is still the workhorse for holding screwworm at bay, but what’s new and worth watching are attempts to upgrade the toolbox. In Uruguay, the National Institute of Agricultural Research (INIA) and Institut Pasteur of Montevideo are building gene-edited screwworm strains designed so that released males pass on traits that render female offspring infertile, a self-limiting approach intended to collapse populations with fewer mass releases than SIT.
This method could also be more durable than SIT, which did work wonders in the past, but has allowed the screwworm population to rise again and become a risk for cattle. Indeed, Maxwell Scott, an entomologist at North Carolina University, and collaborating with the INIA team, told MIT Technology Review that what’s attractive about this method is that knocking a gene drive into the female could disrupt female development, making it very efficient.
Similar methods have been tested and have shown remarkable results. A 2023 study led by the University of California focused on the fruit pest Drosophila suzukii. On paper, the method used was quite simple: use CRISPR Cas9 to develop an edited version of a gene essential to the species’ reproduction and combine the population with the edited gene and the fertile population to mimic a real-world release. The results were promising as the rate of transmission of the edited gene reached 97% to 99%. While this isn’t proof that it will work the same with the screwworm, it does validate the mechanism.
Back to the screwworm and beyond cattle biotech, Texas is also turning to chemistry and delivery. A new Swormlure-5 bait, engineered to mimic the odor profile of open wounds, aims to draw in adult flies for rapid kill, and the Texas DA cites prior deployments where about 90% of flies in targeted areas were eliminated within weeks, with SIT used to mop up the remainder. These measures are attractive because they can be deployed quickly and locally without waiting for full-scale fly factories, though they’re punctual and localized solutions, not necessarily a durable way to get rid of the pest.
It’s important to keep the claims grounded: the World Organisation for Animal Health (WOAH) and the U.S. Food and Drug Administration (FDA) both note there are no approved vaccines or drugs specifically for screwworm myiasis today, and SIT remains the only technique with a decades-long eradication track record. But taken together, gene editing and smarter lures could potentially make the fight against pests much more efficient.
Tackling climate impact: Toward “methane-free” cows
Saving cattle from screwworm flies isn’t all biotech and gene editing can do. A few months ago, Nobel laureate Jennifer Doudna mentioned in an interview a bolder idea: use CRISPR to re-engineer the rumen microbiome so cattle stop producing methane in the first place.
Why go after methane? Agriculture is the largest human source of methane, and livestock account for roughly a third of anthropogenic methane. That makes ruminants central to near-term climate goals, since methane cuts could cool the planet faster than CO2 cuts alone.
Together with UC Davis and UC San Francisco, Doudna’s team at UC Berkley is collaborating on a $70 million donor-funded effort, backed by TED’s Audacious Project, to edit the methanogenic archaea so that methane never forms. The vision is a once-at-birth “probiotic” capsule for calves that creates a lasting shift in the gut ecosystem.
The microbiome-editing approach differs from feed additives, the closest we got to methane-free cattle so far, because it aims at durability and scale. Researchers are cataloging rumen species and enzymes, then using CRISPR to tip the balance, either disabling the methanogens’ pathway or supercharging hydrogen-eating bacteria that outcompete them. If it works, a single neonatal dose could indeed cover pasture-raised herds that are impossible to feed daily.
Meanwhile, biotech cattle feed strategies are already on the market or getting there. 3-NOP (Bovaer) is a small-molecule enzyme inhibitor that targets methyl-coenzyme M reductase (MCR), the key step methanogens use to make CH4 (methane). This solution, developed by Elanco, has regulatory clearance in the EU and Canada, and U.S. regulators have completed review for use in lactating dairy cattle. Trials typically show about 30% methane reductions in dairy (higher in some feedlot settings). The catch: effects persist only while it’s fed, so confinement or daily rationing helps, while grazing systems are harder.
Finally, genomics-guided breeding is gaining traction. Programs now measure methane and assign breeding values, leveraging the fact that methane-related traits show non-trivial heritability, enabling gradual, cumulative reductions across a national herd. Breeding is slower than a pill or additive, but once baked into genetics, the gains persist every generation without daily inputs.
The topic is, however, highly controversial. Let’s take Bovaer, for instance. On several occasions, false claims were made online regarding its approval or its properties. Online posts massively claimed Bovaer wasn’t approved in the EU, or that its active ingredient was present in the milk produced by cows; both claims were addressed. There are also some animal wellness concerns as feed strategies are limited in grazing systems, potentially encouraging enclosed settings in the name of the environment. Gene editing that would offer a once-at-birth solution could solve this duality, but it does come with the usual ethical concerns of gene editing.
To sum it up, microbiome editing goes after permanence and reach (especially for pasture cattle), feed additives deliver immediate, controllable reductions where daily rations are feasible, and breeding offers slow, durable progress. Layered together, they might shrink cattle’s methane footprint without shrinking herds, and that’s exactly why this space is drawing serious biotech attention.
Protecting cattle herds: vaccines and advanced therapeutics
If vaccines cut disease, in the context of cattle health, they also cut antibiotics and zoonotic risk, and the pipeline is moving forward.
In May 2025, a Penn Medicine and USDA National Animal Disease Center team reported an H5 mRNA–LNP vaccine that triggered strong antibody and T-cell responses in Holstein calves and protected them from H5N1 challenge. It’s still early research, but it shows the platform can work in bovines and could be rapidly retargeted as strains shift.
The company behind Bovaer, Elanco, has also partnered with Medgene to commercialize a dairy-cattle H5N1 vaccine developed on Medgene’s USDA-licensed platform. At the time of the collaboration announcement in February 2025, it was in the final stages of conditional-license review.
For bovine respiratory syncytial virus (RSV), a core driver of bovine respiratory disease (BRD), Janssen Vaccines showed that its viral-vector vaccine completely protected calves. Producers already use simpler BRD vaccines. Intranasal options such as Merck Animal Health’s Bovilis Nasalgen and Boehringer Ingelheim’s Bovalto Respi Intranasal that aim to trigger fast local immunity in the airways.
Biotech in cattle will rise or fall on trust, not just tech
The screwworm scare, the push to curb methane, and the new wave of livestock vaccines all point in the same direction. Biotech can solve stubborn problems in cattle health, but progress will depend as much on proof, rules, and trust as on laboratory ingenuity.
Field results matter most for the new tools. The sterile-insect technique already has decades of real-world success; the question is how well the next wave performs outside controlled studies. Microbiome editing aims to deliver long-lived effects in pasture systems, synthetic lures and targeted treatments can knock back local surges, and vaccines help reduce risk when used ahead of, or alongside outbreaks.
Public health and confidence, as well as ethics, sit alongside the science. Gene editing’s appeal in cattle is clear: it can harden herds against disease and heat stress, and, paired with better vaccines, help cut antibiotic use. But it also sits in territory that many file under the genetically modified organism (GMO) appellation, and that brings baggage.
The World Health Organisation notes that no persuasive evidence of unique health risks from approved GM foods compared with conventional ones, though it stresses the importance of case-by-case safety assessment. In the U.S., about 95% of cattle are fed with GMO crops. Additionally, GMO salmon and pigs are already authorized in the U.S.
At the same time, ethical and governance questions remain. From animal welfare and off-target effects to ecosystem impacts, labeling and consumer trust, and different regulatory philosophies, the FDA’s risk-based oversight of “intentional genomic alterations” vs. the EU’s stricter GMO rules for animals. The science is moving fast, but durable adoption depends as much on regulation, transparency, and public confidence as on technical success.
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