New Screwworm Diet Helps Save Money for
Eradication Program By
December 4, 2000
Parasitic screwworm flies, once the scourge of the U.S.
livestock industry, are now being fed a meatless, biodegradable artificial diet
that promises to save the U.S. Department of Agricultures screwworm
eradication program as much as $100,000 annually.
That estimate comes from Agricultural Research Service entomologist
Muhammad F. Chaudhury. In 1999, he made several changes to the artificial diet
used to rear millions of screwworm flies at a factory operated by the
U.S.-Mexican Commission for Eradication of Screwworms in Tuxtla Gutierrez,
Chiapas, Mexico. The factory-raised screwworm flies are subsequently sterilized
by irradiation. These sterile flies are released to mate with wild screwworm
flies--matings that produce no viable eggs and therefore reduce and ultimately
eliminate the wild screwworm population.
Previously, screwworm flies for the eradication program were
raised on a diet of horse meat and honey. The new diet consists of spray-dried
eggs and either honey or molasses. Female screwworm flies laid more eggs on the
meatless diet than on the horsemeat diet.
Yet another improvement: Recycled newspaper can be used in the
screwworm diet to replace an absorbent gel now used for bulk in the larval
diet. Besides further reducing the cost of rearing the insect larvae, recycled
newspaper is biodegradable, while the absorbent gel is not. Larger
factory-scale trials will be conducted in January. Chaudhury presented
information about the economic savings of the new diets at a meeting of the
Entomological Society of America (ESA)
from Dec. 3-7 in Montreal, Canada.
The insect rearing facility in Tuxtla currently produces 150
million sexually sterile flies per week and air shipments are made to support
the U.S.-Panama Screwworm Eradication
Program in Panama City.
On Oct. 4, 2000, Costa Rica was declared free of screwworms.
Panama is currently the only Central American country still working to
eradicate the destructive pest. Total eradication in Panama is expected by
2001. Screwworms, obligate parasites because their larvae eat living flesh,
nearly devastated the U.S. livestock industry in the 1900s. ARS achieved its
worldwide reputation for screwworm control based on the pioneering work of
Edward F. Knipling and Raymond C. Bushland, who developed the sterile insect
ARS is the chief scientific research agency for the
U.S. Department of Agriculture.
Scientific contact: Muhammad F. Chaudhury, ARS Screwworm
Research Laboratory, Tuxtla Gutierrez, Chiapas, Mexico, telephone
011-529-614-1441, fax 011- 529-614-1415, firstname.lastname@example.org.