Federal officials working to keep U.S. free of nightmarish screwworms

By Mary Hightower
U of Arkansas System Division of Agriculture

FAYETTEVILLE, Ark. — The New World screwworm is the stuff of nightmares.

Named for its habit of screwing into the living flesh of warm-blooded animals with its razor-sharp mouth hooks, they are maggots — the larvae of Cochliomyia hominivorax, a fly with large orange eyes, a dark blue or green metallic body bearing three dark stripes.

Adult New World screwworm fly, characterized by its large orange eyes and bluish or greenish metallic body and three back stripes. (Image by  Judy Gallagher (lCreative Commons Attribution 2.0 Generic license)

All but disappeared from the United States since the 1960s, the New World screwworm has prompted fresh concerns from the U.S. Department of Agriculture and the livestock industry after a case was reported in southern Mexico last fall.

This prompted the USDA’s Animal and Plant Health Inspection Service, or APHIS, to put in effect a temporary ban on importation of live cattle, bison, horses and other livestock from Mexico.

“The United States Department of Agriculture had successfully eradicated New World screwworm from the U.S. in 1966,” said Kirsten Midkiff, extension animal health and wellbeing specialist for the University of Arkansas System Division of Agriculture. “The last case that we had in the U.S. was in October 2016 in Florida, and swift action was taken to eliminate the presence by March 2017.

“Because of this new case in the southern part of Mexico, APHIS announced on Dec. 13 that there will be a release of $165 million in emergency funding to protect U.S. livestock, pets, and wildlife,” Midkiff said.

Setting up a barrier

1944 bulletin from Florida Extension Service features discussion on managing screwworm before the pest was eradicated in the U.S. in 1966 (U of A System Division of Agriculture image by Jon Zawislak)

New World screwworms are endemic to Cuba, Haiti, the Dominican Republic, and countries in South America. Panama was considered the border for screwworm prevalence, but recently the screwworm has trended north into Costa Rica, Nicaragua, Honduras, Guatemala, and the southernmost areas of Mexico.

In 1972, USDA and Mexico started a screwworm eradication program to create a biological barrier distributing sterile flies which disrupt reproduction. The sterile flies were raised in a facility in Mexico and dispersed using specially equipped planes. In 2006, a new sterile fly production facility was built in Panama, with flies distributed along the border between Panama and Columbia, pushing the barrier further south. According to the U.S. Embassy in Costa Rica, an average of 60 million sterile flies were dispersed weekly.

Midkiff said the emergency funds are being used to support surveillance efforts, animal health checkpoints, and collaborate with Mexico and Central American countries to establish a new barrier on the Isthmus of Tehuantepec and re-establish the Panamanian barrier.

Precaution and prevention

Maggie Justice, extension beef cattle specialist for the Division of Agriculture, said she’s been getting questions from ranchers. However, she wants to emphasize that “currently, there is no outbreak in the U.S., we have imposed restrictions on live cattle imports from Mexico out of caution.

“This could cause disruption of the overall cattle supply, especially in regions such as Texas and an overall reduced supply of cattle in the market. This also can cause uncertainty in the market,” Justice said. However, “prevention of the screwworm entering the U.S. is imperative, as there could be major economic losses associated with the pest with devastating consequences for animal health and welfare.”

Economic concerns

The United States imported 1.23 million head of feeder cattle from Mexico in 2024. Mexico is second only to Canada in terms of supplying beef to the U.S.

However, during “the last five weeks of the year, we imported zero,” said James Mitchell, extension livestock economist for the University of Arkansas System Division of Agriculture. “This is important because we typically observe a seasonal high in Mexican cattle imports during December. These cattle are fed in U.S. feedlots before being processed into beef in preparation for grilling season, which spans from Memorial Day to Labor Day.”

Mitchell said the import ban increased cattle prices, particularly in Texas and other border states.

“However, it also had negative effects on feedlots already struggling to maintain capacity due to tighter domestic cattle supplies,” he said.

The potential cost of a New World screwworm outbreak in domestic herds could be substantial, depending on its severity. Implementing an import ban is a logical step to reduce the risk of such an outbreak. Prior to its eradication in 1966, New World screwworms cost the U.S. livestock industry more than $100 million annually, according to a 1991 presentation by James E. Novy, assistant chief of program evaluations and planning of veterinary services for USDA.

What to look for

New World screwworm flies lay eggs on an open wound or around an orifice, and after a few hours the eggs will hatch and larvae burrow into the wound to feed. The maggots are unique in that they have sharp mouth hooks that cause extensive damage, tearing into the host tissue. Unlike other species, these maggots will only feed on living tissue.

“Being vigilant about New World screwworm is the key to keeping it out of the United States,” Midkiff said.

 Early signs for the screwworm are enlarged or draining wounds, discomfort, and the presence of eggs or larvae near superficial injuries, according to APHIS. Other signs in animals — both mammals and birds — may be irritated behavior, head shaking, the smell of decay, evidence of fly strike, or the presence of maggots in a wound.

“If screwworms are diagnosed, then affected animals will be quarantined until daily wound care and treatments of infected animals are successful,” Midkiff said. “If the USDA investigates cases and it is deemed necessary, then additional control measurements including insecticidal treatment of the environment or sterile screwworm fly release may occur.”

If you suspect a screwworm infestation, contact your veterinarian or state veterinarian.

To learn about extension programs in Arkansas, contact your local Cooperative Extension Service agent or visit www.uaex.uada.edu. Follow us on X and Instagram at @AR_Extension. To learn more about Division of Agriculture research, visit the Arkansas Agricultural Experiment Station website: https://aaes.uada.edu. Follow on X at @ArkAgResearch. To learn more about the Division of Agriculture, visit https://uada.edu/. Follow us on X at @AgInArk. 

Survey assesses Mexican consumers’ opinions on GMO corn import ban

By John Lovett
University of Arkansas System Division of Agriculture
Arkansas Agricultural Experiment Station

FAYETTEVILLE, Ark. — A fully implemented ban on genetically modified corn in Mexico could disproportionately affect the nation’s lower-income consumers, according to a recently published study by agricultural economists with the University of Arkansas System Division of Agriculture.

It would also have a negative impact on American farmers. Over 90 percent of corn grown in the United States is genetically modified, and Mexico is the second-largest importer of U.S. corn after China. Eggs and poultry meat account for about half of protein intake, and tortillas provide 13 to 20 percent of caloric intake for Mexicans, according to articles and studies cited in the Division of Agriculture study titled “Potential response of Mexican consumers to a ban on genetically modified maize imports.”

CORN SURVEY — Agricultural economists with the Arkansas Agricultural Experiment Station conducted a survey of Mexican consumers on their nation's ban of genetically modified corn. (U of A System Division of Agriculture)

“More than half of the people we surveyed in Mexico were not even aware of the ban, and of those who did know about it and supported it, many of them changed their opinion when they saw how much prices could go up and how many jobs could be lost,” said Brandon McFadden, a lead author of the study and a professor of agricultural economics and agribusiness for the Arkansas Agricultural Experiment Station, the research arm of the Division of Agriculture.

The study, published in the journal Food Security, was co-authored by Lawton Lanier Nalley, Alvaro Durand-Morat, Katie Loethen, and Wei Yang. Nalley is head of the agricultural economics and agribusiness department. Durand-Morat is an associate professor and the L.C. Carter Endowed Chair in the department. Loethen is an agricultural economics graduate student at the University of Arkansas, and Yang is an agricultural economics graduate student at Texas A&M University.

“While this study primarily focused on the impacts to Mexican maize consumers, there are tangible impacts to the U.S. maize industry from the ban,” Nalley said. “Mexico relies heavily on U.S. maize imports, mainly yellow maize, for livestock production. Since over 90 percent of U.S. maize is genetically modified, the decree would drastically impact bilateral trade should the GM ban be implemented.”

Maize is the Spanish word for what is called corn in the U.S. The industry uses “GM” and “GMO” interchangeably for genetically modified, or genetically modified organism.

McFadden said the study was conducted to fill gaps in understanding what Mexican consumers would be willing to pay for the impacts of Mexican bans on genetically modified corn and the herbicide glyphosate. The research also helps estimate the burden on low-income consumers who could likely not afford the premiums for products made from non-genetically modified corn, he added.

Presidential decrees

On Dec. 31, 2020, President Andres Manuel Lopez Obrador’s administration published a decree calling for the nation to phase out the herbicide glyphosate and genetically modified maize, or corn, for animal and human consumption by Jan. 31, 2024. In a follow-up decree on Feb. 13, 2023, the Mexican government exempted genetically modified corn for animal feed.

President Claudia Sheinbaum, who took office Oct. 1, has indicated her administration will continue enforcing the decree.

The consumer perception study, led by McFadden as the Tyson Endowed Chair in Food Policy Economics, was conducted in April 2023 and surveyed 1,301 Mexicans who were age 18 or over. About 5 percent of the sample did not consume all the food products, so 1,238 respondents completed the survey. Durand-Morat, whose native language is Spanish, translated the questions and the results.

What is GM corn?

Most genetically modified corn is created to resist insect pests or tolerate herbicides. Bacillus thuringiensis, or Bt, corn is a genetically modified corn that produces proteins that are toxic to certain insects but not to humans, pets, livestock, or other animals, according to the U.S. Food and Drug Administration.

“These are the same types of proteins that organic farmers use to control insect pests, and they do not harm beneficial insects, such as ladybugs,” the FDA noted. “GMO Bt corn reduces the need for spraying insecticides while still preventing insect damage. While a lot of GMO corn goes into processed foods and drinks, most of it is used to feed livestock, like cows, and poultry, like chickens.”

Most crops fed to animals are genetically modified, but not those directly eaten by humans, according to Michael Kidd, professor of poultry nutrition in the Center of Excellence for Poultry Science for the Division of Agriculture.

Willing to pay?

On average, those surveyed were willing to pay a premium of 73 percent for chicken, 50 percent for eggs, and 50 percent for tortillas produced with non-genetically modified corn. These premium estimates are more significant than the potential price increases of 67 percent for chicken and 30 percent for tortillas, as estimated by a 2022 World Perspectives study that provided estimates on price increases.

Breaking the results down by groups, however, is more of a mixed bag, McFadden said. Out of the entire group of respondents, less than half — 46 percent — were aware of the decrees. The people who were aware of and supported the ban were willing to pay higher than average for non-genetically modified products and animal products that had eaten GM feed. Respondents who supported it were willing to pay 91 percent more for chicken, 71 percent more for eggs, and 66 percent more for tortillas.

In the lowest-income category with an annual income of less than 7,000 pesos — or about $350 — those unaware of the ban were only willing to pay premiums of 46 percent for chicken, 21 percent for eggs, and 25 percent for tortillas.

Human health was the largest reason given by respondents supportive of the GMO ban, representing 85 percent of that group. Other less significant reasons included protecting Mexican heritage, environmental concern and protecting cultural heritage.

Public opinion at odds with FDA

The weighted average of responses indicated that consumers did not feel that genetically modified products of corn were safe to eat in tortillas. However, they felt it was safer than consuming poultry fed genetically modified corn feed. Those surveyed also considered genetically modified corn grown in Mexico as safer than that grown in the U.S.

The consumer perception results clash with the FDA’s position on genetically modified corn for chicken feed and the Mexican government’s exemption on genetically modified corn for animal feed.

The safety perception rankings from survey respondents for tortillas and tamale husks were significantly higher than eggs or chicken. And consumers felt it was safer for eggs than chicken meat. The results for the safety rankings of products align with research in the U.S., McFadden noted, concluding that consumers are generally more averse to fresh products like meat from animals fed with genetically modified corn than processed products using genetically modified corn.

The FDA, basing its statement on independent studies, says there is “no difference in how GMO and non-GMO foods affect the health and safety of animals.” More than 95 percent of animals used for meat and dairy in the United States eat genetically modified crops.

“The DNA in the GMO food does not transfer to the animal that eats it,” the FDA states. “This means that animals that eat GMO food do not turn into GMOs. Similarly, the DNA from GMO animal food does not make it into the meat, eggs, or milk from the animal. Research shows that foods like eggs, dairy products, and meat that come from animals that eat GMO food are equal in nutritional value, safety, and quality to foods made from animals that eat only non-GMO food.”

The FDA also notes that the U.S. Environmental Protection Agency “continues to find that there are no risks to public health when glyphosate is used in accordance with its current label.” The International Agency for Research on Cancer concluded that glyphosate may be a carcinogen, while several others, including the European Food Safety Authority and the Joint Food and Agriculture Organization/World Health Organization Meeting on Pesticide Residues, have determined that it is unlikely to be a carcinogen, the FDA added.

Food security and jobs

About 45 percent of Mexicans live in poverty, and 23 percent are food insecure, the consumer perception study noted. If the estimated price changes reported by World Perspectives in 2022 are correct, the ban will likely exacerbate food insecurity, McFadden said, because lower-income Mexican consumers spend a larger proportion of their relative and absolute income on tortillas than the wealthiest people.

In addition to the increases in corn prices, the World Perspectives study estimated the original decree would result in 56,958 jobs lost in Mexico. Supporters of the ban were asked if they would still support the decree given a potential loss of jobs for 55,000 Mexicans.

The proportion of respondents who were aware and supported the decree decreased from 77 to 46 percent when provided information about the potential jobs lost due to the decree. The decree support dropped to 56 percent when provided information about increases in corn prices.

McFadden said employment reductions could come from a cascading effect of increased food prices, which decreases spending on other goods and in turn a decreased gross domestic product, the measure of a country's economic health.

Previous bans in other countries

Food security risks associated with genetically modified food bans have taken place in other countries, the consumer perception study noted. In 2020, Zimbabwe lifted an import ban on genetically modified foods that had been in place for 12 years after the worst drought in decades resulted in more than half of the population needing food aid. Kenya had also banned genetically modified crops in 2012, then lifted the ban in 2022 after soaring food prices amid the African nation’s worst drought in four decades.

To learn more about the Division of Agriculture research, visit the Arkansas Agricultural Experiment Station website. Follow us on X at @ArkAgResearch, subscribe to the Food, Farms and Forests podcast and sign up for our monthly newsletter, the Arkansas Agricultural Research Report. To learn more about the Division of Agriculture, visit uada.edu. Follow us on X at @AgInArk. To learn about extension programs in Arkansas, contact your local Cooperative Extension Service agent or visit uaex.uada.edu.

U.S Rep. Rick Crawford said he is optimistic about steel agreement between the U.S, Mexico

KUAR | By Ronak Patel

Last week, the United States and Mexico reached a deal to address China’s ability to evade tariffs that were created to protect North American products that are made with steel, according to the Arkansas Democrat-Gazette.

Lael Brainard, director of the White House National Economic Council, said the agreement is a way to enforce existing tariffs, according to the Associated Press.

“The president [Biden] is taking action to close loopholes left by his predecessor [Trump] that allowed China to circumvent trade rules,” she said.

U.S Rep. Rick Crawford said he is optimistic about steel agreement between the U.S, Mexico

Flickr Image

Governor Hutchinson Authorizes 90-Day Deployment Of Up To 40 National Guard Members to U.S. Southern Border

LITTLE ROCK – Governor Asa Hutchinson has authorized a 90-day deployment of up to 40 members of the Arkansas National Guard to Texas to assist with security at the state’s border with Mexico.

“I have authorized this mission in response to an official request from Texas on the urgent matter at our southern border,” Governor Hutchinson said. “My hope is that our 90 days of support will improve the security of our country and reduce the adverse impact of illegal immigration on Arkansas.”

The 90-day deployment will be consistent with a training mission for the National Guard.