The Mediterranean Fruit Fly
Plant Protection and Quarantine
May 1999
The Mediterranean fruit fly (Ceratitis capitata), commonly called
Medfly, or Moscamed in Spanish, is one of the world's most destructive
agricultural pests.
The female Medfly attacks ripening fruit, piercing the soft skin and
laying eggs in the puncture. The eggs hatch into larvae (maggots), which
feed inside the fruit pulp.
Appearance and Life Cycle
The adult Medfly is slightly smaller than a common housefly and is
very colorful. It has dark blue eyes, a shiny, black thorax (back),
and a yellowish abdomen with silvery cross bands. Its wings, normally
drooping, display a blotchy pattern with yellow, brown, and black spots
and bands.
The life cycle of the Medfly has five phases:
(1) the adult female deposits eggs under the skin of fruit, (2) the
eggs hatch and produce maggots or wormlike larvae, (3) the larvae feed
on the pulp of fresh fruits and vegetables before dropping to the ground,
(4) the larvae transform into pupae in the soil, and (5) the pupae mature
into adults and emerge from the soil. Under tropical summer weather
conditions, the Medfly completes its life cycle in 21 to 30 days.
History
The Medfly originated in Africa. It has since spread throughout the
Mediterranean region, southern Europe, the Middle East, western Australia,
South and Central America, and Hawaii. In general, it is found in most
tropical and subtropical areas of the world.
The Medfly became established in Hawaii in 1910. Hawaii remains infested
with this pest, and no eradication program is currently under way. The
first U.S. mainland infestation occurred in Florida in 1929. Several
infestations have occurred on the mainland since then. However, State
and Federal eradication programs in California, Florida, and Texas have
prevented it from becoming established.
Eradication
The eradication of the Medfly is accomplished by action in three areas:
survey, regulation, and control.
Survey-The U.S. Department of Agriculture's (USDA) Animal and
Plant Health Inspection Service (APHIS), along with State departments
of agriculture, maintains trapping programs in high-risk areas of States
susceptible to Medfly establishment. When one or more Medflies is collected
in an area, APHIS and State officials immediately implement a delimiting
survey. Using the detection site as the focal point, field crews position
additional traps to determine if an infestation exists and to locate
and define the limits of the infested area.
Regulation-If an infestation exists, Federal and State quarantine
regulations are imposed to help prevent artificial spread of the pest.
Federal quarantine laws regulate the interstate movement of any article
that may harbor the fly. State regulations control the movement of these
articles going to uninfested areas of the same State. Articles regulated
by State and Federal authorities include all Medfly-host fruits and
vegetables present in the area. Open-air fruit and vegetable stands
must provide protective covers for the produce to prevent infestation,
and commercial and home-grown produce may not be moved without special
inspection and treatment.
Control-Three kinds of treatment are used alone or in combination
to eradicate the Medfly.
Aerial and Ground Bait Spray Application
This spray is approved for use by the Environmental Protection Agency.
The spray contains minimal amounts of an insecticide and a protein/sugar
bait that attracts the flies.
Sterile Insect Technique (SIT)
In the SIT, Medflies are reared in large quantities, sterilized with
a small amount of irradiation, and released into areas where they mate
with wild Medflies. Such matings do not produce offspring. Eventually
the wild population is eliminated through attrition.
SIT is most effective against low-level Medfly populations where a
high proportion of sterile to wild flies can be achieved to ensure success.
Initial applications of insecticide bait spray are sometimes necessary
to bring local populations down to low densities.
Insecticide Application to Soil Under Host Trees
These products will kill some larvae as they enter the soil to pupate
and most of the adults as they later emerge.
Currently, application of insecticide to the soil is used only when
larvae are detected. The preferred and most popular eradication strategy
is an integrated approach combining all three treatments, with emphasis
on the use of SIT.
Damage
In the United States, the Medfly could attack peaches, pears, plums,
apples, apricots, avocados, citrus, cherries, figs, grapes, guavas,
kumquats, loquats, nectarines, peppers, persimmons, tomatoes, and several
nuts.
If the Medfly were to become established, consumer prices would go
up and produce would become less available. In addition, backyard gardens,
as well as commercial production areas, would require increased use
of pesticides on a routine basis.
In 1993, APHIS estimated that annual losses attributable to the Medfly
in the continental United States would be about $1.5 billion annually
if this exotic pest were to become established. These losses would come
in the form of export sanctions, lost markets, treatment costs, reduced
crop yields, deformities, and premature fruit drop.
The Medfly in Mexico and Guatemala
In 1977, the Governments of the United States, Mexico, and Guatemala
initiated a cooperative program known as the Moscamed Program to eradicate
the Medfly from Mexico and to maintain a barrier in Guatemala to halt
the Medfly's northern spread. This program is designed to suppress Medfly
populations and reduce the risk of introduction into the United States.
Mexico has been free of Medfly since 1982, except for outbreaks in
the southernmost State of Chiapas, adjacent to Guatemala.
The Moscamed Program operates two facilities that produce sterile Medfliesone
in Metapa de Dominguez, Mexico, and one in El Pino, Guatemala.
Keeping the Medfly Out
Many of the insects, weeds, and plant diseases that attack U.S. crops
are foreign invaders. APHIS administers agricultural quarantine laws
to help keep foreign plant pests and diseases out and to control domestic
pests and diseases of limited distribution.
Travelers returning to the continental United States from Hawaii or
a foreign country are prohibited from bringing into the country fresh
fruits, meats, plants, birds, and plant and animal products that may
harbor pests or diseases.
In fiscal year 1998, agricultural officers cleared for entry more than
400,000 aircraft that brought travelers and cargo to the United States.
In the same year, officers intercepted more than 1.8 million illegal
plants, animals, or plant and animal byproducts. More than 52,000 plant
pests and diseases identified as dangerous to the U.S. agricultural
industry were also intercepted.
Additional Information
If you have questions about the Medfly, call the central office of
APHIS' Plant Protection and Quarantine (PPQ) unit at (301) 734-8645,
or contact a U.S. Federal regulatory official, listed in the Federal
Government section of your telephone directory under USDA, APHIS, PPQ.
You may also call your State's regulatory officials, usually listed
under department of agriculture, plant protection or regulatory division,
in the State government section of your telephone directory.
In addition, APHIS' Internet home page (http://www.aphis.usda.gov)
provides up-to-date information on various agricultural pests and diseases
and other related topics.
The U.S. Department of Agriculture (USDA) prohibits discrimination
in all its programs and activities on the basis of race, color, national
origin, gender, religion, age, disability, political beliefs, sexual
orientation, or marital or family status. (Not all prohibited bases
apply to all programs.) Persons with disabilities who require alternative
means for communication of program information (Braille, large print,
audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600
(voice and TDD).
To file a complaint of discrimination, write USDA, Director, Office
of Civil Rights, Room 326-W, Whitten Building, 14th and Independence
Avenue, SW, Washington, DC 2025-9410 or call (202) 720-5964 (voice and
TDD). USDA is an equal opportunity provider and employer.
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