McInnis, who is at ARS' U.S.
Pacific Basin Agricultural Research Center in Honolulu, Hawaii, helped design
the pioneering tests of the Toliman TSL medflies in Guatemala. He did the work
with David Lance of USDA's Animal and Plant Health Inspection Service, formerly
at Waimanalo, Hawaii, and now at Cape Cod, Massachusetts; Pedro Rendon and
colleagues with APHIS in Guatemala City, Guatemala; and co-researchers from the
government of Guatemala.
Rendon and staffers at the International Atomic Energy Agency developed the
Toliman TSL strain by crossing the Viennese TSL flies with a Guatemalan strain
of medfly. Toliman TSLs needed for the collaborative research were produced at
a medfly factory in El Pino, outside Guatemala City, Guatemala. APHIS and the
Guatemalan government run that insectary.
Native to Africa, medflies have lived in Guatemala since at least the 1960s.
The El Pino factory can produce up to about 50 billion medflies a year. Some
are released in Guatemala, forming a living barrier that helps stop the species
from advancing north into the United States. Other steriles are shipped to the
United States for use in regional wars against medfly.
California, for instance, has an enormous need for steriles for its ongoing
campaign in Los Angeles, Riverside, Orange, and San Bernardino counties.
The state last year used 15 billion steriles for this war on medflies.
Florida has a similar campaign and uses 70 million sterile medflies a week in a
The Guatemalan studies, begun in 1993, included the largest-ever outdoor
test of TSL medflies. For these rigorous examinations of the insects'
proficiencies, more than 120 million Toliman TSLs and the lab's conventional
"Petapa" strain of neutered medflies were set free in coffee fields
As part of the experiment, researchers collected coffee berries that had
been visited by the female flies to determine whether the hidden eggs were
infertile. In plots where the Toliman TSLs had been released, the proportion of
infertile eggs to fertile eggs was from three to five times greater than that
of a standard lab-reared strain.
The Toliman TSLs also scored high in two other critical categories: field
dispersal, or ability to roam throughout fields instead of staying in one
place, and field survival, or ability to adapt to climate and other
The ARS, APHIS, and Guatemalan investigators were the first to move TSLs out
of the lab and into mass production. As a result of the team's exhaustive
studies of Toliman TSLs, the El Pino fly factory is now planning to produce
only this top-performing strain.
Two major sterile-medfly factories in Hawaiione operated by APHIS and
the other by the State of Californiaalso plan to produce TSLs
exclusively. In all, they could provide more than 400 million steriles a week
for mainland campaigns.
Largely because of the impressive results of the Guatemalan field tests with
Toliman TSLs, other countries threatened by medfly invasions are opting to use
TSLs in their own mass-rearing programs. Chile and the Portuguese island of
Madeira, for example, are already using strains of top-performing TSLs to guard
their crops against the ravages of wild medflies.By
Marcia Wood, Agricultural
Research Service Information Staff.
This research is part of Crop Protection and Quarantine, an ARS National
Program (#304) described on the World Wide Web at
Donald O. McInnis is at
the USDA-ARS U.S. Pacific
Basin Agricultural Research Center, 2727 Woodlawn Dr., Honolulu, HI 96822;
phone (808) 988-8232, fax (808) 988-7290.