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Officials Countering Feared Screwworm Invasion

August 13, 1987

WASHINGTON (AP) _ International jet travelers apparently have picked up some hitchhiking screwworms from Latin America lately, prompting the Agriculture Department to hurl millions of sexually sterile screwworm flies against the suspected invaders.

Later this week the first of a new wave of sterile flies will be released in two Southern cities in a biological campaign against screwworms that might have entered the United States from Honduras.

Bert W. Hawkins, head of the department’s Animal and Plant Health Inspection Service, said Wednesday that approximately two million sterilized flies will be released twice weekly for about six weeks in areas 20 miles around Panama City, Fla., and New Orleans, La.

The agency will conduct surveillance and public awareness programs in the two areas and along Interstate 10 between the two cities.

If screwworms become established in the Southeastern states, it could cost up to $100 million to eradicate them, Hawkins said.

Screwworms are the parasitic larvae or maggots of a blowfly species that feed on the flesh of warmblooded animals. The female fly - about twice the size of an ordinary housefly - lays eggs in an open wound, in which the larvae hatch and grow to about a half-inch long in five to seven days of feeding.

If not treated, the animal can die. Humans also have been known to be infested by the maggots.

Adult female screwworm flies usually mate only once in their lifetime. Thus, when a natural, fertile female mates with a sterile male, she lays eggs that don’t hatch - and no screwworms are produced.

Hawkins said the action was prompted after identification Aug. 5 of screwworms in a dog that passed through the New Orleans International Airport on its way to Florida from Honduras.

″The dog, a Doberman, was picked up at the airport on July 31 and stayed overnight in an outside kennel at a New Orleans motel,″ Hawkins said. ″The next day, the dog traveled by camper to Panama City, Fla., where it was taken to a local veterinarian for treatment of a back wound.″

Hawkins said the veterinarian discovered the larvae and informed a state veterinarian, who notified the USDA agency. Samples tested at the department’s veterinary laboratory in Ames, Iowa, identified the larvae as screwworms.

The technique of releasing sexually sterile flies has been used successfully since the late 1950s in parts of the Southeast and Southwest. The United States was declared free of screwworms in 1966, although small infestations occurred after that, mostly along the U.S. border with Mexico.

In 1972, a cooperative program was begun with Mexico, and by 1985 screwworms were eliminated from virtually all of that country, Hawkins said.

A plant capable of producing more than 500 million sterile flies a week through irradiation was built in southern Mexico near the narrow Isthmus of Tehauntepec, and a barrier zone of sterile flies was established to prevent reinfestations of the northern area.

The zone was moved farther south to the Yucatan Peninsula, and now the pest is almost gone from that area, Hawkins said.

″Now we’re working to push the screwworm even further south into Guatemala and Belize, and establish the barrier along the border with Honduras and El Salvador,″ he said. ″We hope to eradicate the screwworm from Guatemala within the next year or so.″

This is the second recent incident in which an infested dog has triggered a screwworm campaign. In April, larvae were identified in a hunting dog being returned to the United States from Venezuela after the animal passed through airports in Miami, Fla., and Albuquerque, N.M.

In that instance, millions of sterile flies were released over a six-week period. No infestations developed in either area.


WASHINGTON (AP) - This year’s Pacific Northwest crop of chickpeas, or garbanzos, a regular fare at salad bars in many parts of the country, has been riddled by fungus, but the Agriculture Department says help is on the way from the war-torn Mideast.

A fungal disease called Ascochyta blight is leaving fields of chickpeas looking as if ″someone went through them with a blowtorch,″ said Walter J. Kaiser Jr., a plant pathologist in the department’s Agricultural Research Service in Pullman, Wash.

Kaiser and other researchers have identified genetic resistance to the fungus in chickpea plants collected by the International Center for Agricultural Research, Aleppo, Syria.

The scientists plan to use the new plant material, or germplasm, to breed blight resistance into commercial varieties of chickpeas, the agency said Wednesday in a report released here.

Meanwhile, the Pullman chickpea team said farmers can rid their fields of the blight temporarily by plowing under straw and other crop residues. Agency scientists discovered the disease in 1983.

Kaiser said this year’s blight wiped out more than half of the $6 million chickpea crop planted on 15,000 acres in eastern Washington and northwestern Idaho, the largest producing area in the country.

Another 6,000 to 8,000 acres of chickpeas are grown in coastal valleys of southcentral California and are not affected so far by the disease.


WASHINGTON (AP) - This year has a few months remaining, but already the Agriculture Department is promoting its 1988 outlook conference.

″Outlook ’88 will provide in-depth analysis of commodity prospects that farmers and businesses can use to plan for 1988,″ said Ewen Wilson, who has been designated as assistant secretary for economics.

The annual conference will be held here Dec. 1-3, he said Wednesday. Government and industry analysts are asked to assess the outlook for agriculture in the coming year.

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