|Crop Knowledge Master|
Ceratitis capitata (Wiedemann)
|Mediterranean Fruit Fly|
Ronald F.L. Mau, Extension Entomologist
Jayma L.Martin Kessing, Educational Specialist
Department of Entomology
Updated by: J.M. Diez April 2007
The Mediterranean fruit fly, or Medfly, is one of the world's most destructive fruit pests. Because of its wide distribution over the world, its ability to tolerate cooler climates better than most other species of fruit flies, and its wide range of hosts, it is ranked first among economically important fruit fly species. This pest attacks more than 260 different fruits, flowers, vegetables and nuts. Thin-skinned, ripe, succulent fruits are preferred. Host preferences vary in different regions. Plant hosts include avocado, banana, bittermelon, carambola (star fruit), coffee, guava, mango, papaya, peppers and persimmon. Although several species of cucurbits have been recorded as hosts of the Medfly, they are considered very poor hosts. Some hosts have been recorded as Medfly hosts only under laboratory conditions and may not be attacked in the field. Knowledge of the hosts in one country often aids in correctly predicting those which are most likely to be infested in a newly infested country, but what may be a preferred host in one part of the world may be a poor host in another. An extensive host list is provided by Weems (1981).
The species originated in the Mediterranean region of Europe and North Africa and is not known to be established in the mainland US. It has been detected in Florida and California, especially in recent years, and each infestation required intensive and massive eradication and detection procedures so that the pest did not become established. The Medfly is established in the Western Hemisphere in Argentina, Bermuda, Brazil, Costa Rica, Hawaii, and Uruguay. It occurs in Western Australia, in many countries in Europe and Africa, and in Asiatic countries in the Mediterranean area, such as Israel, Jordan, Lebanon and Turkey.
Mediterranean fruit flies were accidentally introduced into Hawaii from Australia around 1907. They are usually found at upper elevations, although breeding has occurred in lower elevations on Kauai (Vargas, et. al., 1983).
The damage to crops caused by Mediterranean fruit flies result from 1) oviposition in fruit and soft tissues of vegetative parts of certain plants, 2) feeding by the larvae, and 3) decomposition of plant tissue by invading secondary microorganisms.
Larval feeding damage in fruits is the most damaging. Mature attacked fruits may develop a water soaked appearance. Young fruits become distorted and usually drop. The larval tunnels provide entry points for bacteria and fungi that cause the fruit to rot. These maggots also attack young seedlings, succulent tap roots, and stems and buds of host plants.
On papaya, the Mediterranean fruit flies are rare pests in field situations, melon flies are considered occasional pests and the oriental fruit flies are primary pests. Although the actual injury on papaya by fruit flies is relatively low, these flies are considered a major pest of papaya in terms of exporting from Hawaii to the US Mainland and Japan. It is therefore necessary to treat the papaya fruits with post-harvest quarantine treatments.
The economic importance of the Medfly cannot be evaluated entirely from the standpoint of the actual damage to the various crops affected. It must also be considered from the standpoint of quarantine.
Quarantine laws aimed at preventing the entry and establishment of flies in areas where it does not occur have been established and are vigorously enforced. The US Government has strict laws regulating the movement of certain commodities to prevent the establishment of Medfly into the continental US. The Japanese Government restricts the entry of commodities attacked by this pest into their country.
The length of time required for the Medfly to complete its life cycle under tropical conditions is 21-30 days.
Eggs are very slender, curved, 1/25 inch long, smooth and shiny white. They are deposited under the skin of fruit that is just beginning to ripen, often in an area where some break in the skin has already occurred. Several females may use the same deposition hole with 75 or more eggs clustered in one spot. each female will deposit 2 to 10 eggs. Eggs hatch in 1.5 to 3 days in warm weather.
Larvae pass through three larval stages, or instars. They are shaped typical of fruit flies, being elongate, cream colored, cylindrical maggot-shaped, anterior end narrowed and somewhat recurved ventrally, with anterior mouth hooks, and flattened caudal end. Length of first larval stage is 1/25 inch or less, body mostly transparent; the second larval stage is partially transparent with the fruit in the gut visible; the fully grown third larval stage is 1/4 to 1/3 inch long, with a body fully opaque white or the color of ingested food. Exact size of larva depends on diet. The larvae can be distinguished from other fruit fly larvae by the anterior, or thoracic, spiracles that bear small, finger-like tubules ranging from 7 to 11 in number, typically 9 to 10 in number. The larval stage may last as short as 6 to 10 days or as long as 14 to 26 days depending on temperature and host. By the time the larvae have fully developed and are ready to pupate, the fruit has usually dropped to the ground where pupation occurs.
Pupae are cylindrical, approximately 1/8 inch long, and dark reddish brown. Minimum duration of the pupal stage is 6-13 days when the mean temperature ranged from 76û-79û F. Pupae usually develops in soil an inch or two below the surface.
The adult is 1/6 to 1/5 inch long which is about two thirds the size of a house fly. The general color of the body is yellowish with a tinge of brown, especially the abdomen, legs, and some of the markings on the wings. The oval shaped abdomen is clothed on the upper surface with fine, scattered black bristles, and has two narrow, transverse, light colored bands on the basal half. The female can be distinguished by its long ovipositor at the apex of the abdomen. When fully extended, the ovipositor (the egg laying tube) is about 6 times as long as its greatest width.
The top surface of the thorax is convex, the ground color creamy-white to yellow, marbled with black blotches. The lighter areas are clothed with very fine bristles, and several prominent black bristles arise from the black areas of the thorax.
The wings, usually held in a drooping position on live flies, are broad, transparent and glassy with black, brown and brownish yellow markings, with tints appearing faded. There is a fairly wide, brownish yellow band across the middle of each wing. The extreme base is blotched with brownish yellow, with the rest of the basal area curiously marked with black, forming dark lines of the radiating wing veins, with dark spots between them.
The head of the male bears two long, black bristles with broadly flattened, somewhat diamond shaped tips, arising between the eyes near the antennae. The eyes are reddish purple.
Female Medflies lay 1 to 10 eggs in a cavity 1/25 inch deep. She may lay as many as 22 eggs per day and as many as 800 eggs during her lifetime (usually about 300). Females usually die soon after they stop ovipositing.
Adults die in greatest numbers within 2-4 days after emergence if they cannot obtain food. Usually about 50% of the flies die during the first 2 months after emergence. Some adults may survive up to a year or more under favorable conditions of food, water, and cool temperatures. When host fruit is continuously available and weather conditions favorable, successive generations will be large and continuous. Lack of fruit for 3 to 4 months reduces the population to a minimum.
When the eggs hatch, the larvae begin feeding almost immediately. Tunnels are formed, but the larvae often feed together in the same vicinity until they are nearly fully grown.
Larvae leave the fruit in largest numbers at or just after daybreak and pupate in the soil or whatever is available.
Adults emerge from the pupal cases in largest numbers early in the morning during warm weather and emerge more sporadically in cooler weather. They can fly short distances, but winds may carry them a mile or more away. Copulation may occur at any time throughout the day. Newly emerged adults are not sexually mature. Males often show sexual activity 4 days after emergence, and copulation has been observed 5 days after emergence. Most females are ready to mate from 6 to 8 days after emerging from the pupa. Both sexes are sexually active throughout the day.
One of the more effective mechanical control methods is bagging the fruit to exclude egg laying. Trapping is an alternative method but it has not been completely effective.
The principal cultural control method used for controlling this pest is field sanitation. Field sanitation directed toward the destruction of all unmarketable and infested fruits. Infested fruit should be buried 3 feet under soil surface with an addition of sufficient lime to kill larvae. Harvesting fruit weekly also reduces food sources from which large populations may develop by keeping the quantity of ripe fruit on the trees to be minimum. Other procedures that reduce the amount of in-field breeding of medflies should be used.
Thirty-two species and varieties of natural enemies to fruit flies were introduced to Hawaii between 1947 and 1952 to control the fruit flies. These parasites lay their eggs in the eggs or maggots of fruit flies and emerge in the pupal stage. Only three, Opius longicaudatus var. malaiaensis Fullaway, O. vandenboschi Fullaway, and O. oophilus Fullaway, have become abundantly established. These parasites are primarily effective on the oriental and Mediterranean fruit flies in cultivated crops.
A number of parasites have been introduced into Hawaii to control Medfly specifically. The most important were the braconid wasps, Opius humilis and Diachasma tryoni. Later, parasites of the Oriental fruit fly were found destroying the Mediterranean fruit fly. They are Biosteres oophilus, B. vandenboschi, and B. longicaudatalisted in order of effectiveness.
Chemical sprays have not been completely effective in protecting fruit from medflies. Egg laying requires only a few minutes and chemical residues do not kill adults within this time frame.
Proteinaceous liquid attractants in insecticide sprays is a recommended method of controlling adult Mediterranean fruit fly populations in the vicinity of crops. The bait insecticide sprays are applied to broad leaf plants that serve as refugia for Mediterranean fruit fly adults. Baits serve to encourage the adults (especially females) to feed on the spray residue and can provide good rates of kill. To be effective, bait-insecticide sprays must be used in combination with good sanitation practices. These practices include destruction of unmarketable fruit on every harvest date, and destruction of crop residues immediately after economic harvest has been completed.
There is no listing for Nu-Lure as of April 2007.
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Christenson, L. D. and R. H. Foote. 1960. Biology of Fruit Flies. Ann. Rev. Entomol. 5: 171-192.
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Hardy, D. E. & M. D. Delfinado. 1980. Ceratitis capitata (Wiedemann). pp. 100-102. In: Insects of Hawaii. A Manual of the Insects of the Hawaiian Islands, including an Enumeration of the Species and the Notes on their Origin, Distribution, Hosts, Parasites, etc. Volume 13. Diptera: Cyclorrhapha III. University of Hawaii Press, Honolulu. 451 pages.
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Lockwood, S. 1957. Mediterranean Fruit Fly, Ceratitis capitata. Loose-Leaf Manual of Insect Control. California Department of Agriculture.
Marsden, D. A. 1979. Insect Pest Series, No. 9. Melon Fly, Oriental Fruit Fly, Mediterranean Fruit Fly. University of Hawaii, Cooperative Extension Service, College of Tropical Agriculture & Human Resources.
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Weems, H. V. Jr. 1981. Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera; Tephritidae). Entomology Circular No. 230. Fla. Dept. Agric. and Consumer Serv., Division of Plant Industry.