The oldest populations of mediterranean fruit flies (a.k.a. medflies) can be traced back to the African tropics in the Ethiopian biogeographic region. This species is native to both the Ethiopian and Palearctic regions, and introduced populations have since been discovered in all of the biogeographic regions.
Transportation of fresh fruit by air (either commercially, or incidentally by travelers) has greatly increased the risk of accidental introduction of this species into other parts of the world, and strong efforts are made to prevent its spread. (Copeland, et al., 2002; Dekker and Messing, 2005; Thomas, et al., 2001)
In their native home range (sub-Saharan Africa), medflies are found in forests, open woodland in highland areas, and at the coast, shrublands, and dunes. Their dispersal across suboptimal habitats, such as areas where woody vegetation is dominant, is possible because of their ability to both exploit plants in dry habitats and their ability to migrate over moderate-to-substantial distances.
The body ofis protected by an exoskeleton made of chitin. As in all insects, the body has three main segments: the head, thorax, and abdomen; as well as three pairs of legs. The oval-shaped abdomen is yellowish with two white bands. It is covered by black bristles. The thorax is whitish-yellow with patches of black. The eyes are reddish-purple, transforming to black within 24 hours of death. The single pair of wings is translucent and embellished with patterns of brown, yellow, black, and white.
Medflies exhibit sexual dimorphism in that females are larger than males and can be identified by a yellow wing pattern and pointed ovipositor (about 1.2 mm long) which is used to plant eggs within the host fruit. Males have more exaggerated features such as more brightly colored eyes, longer front legs, and a pair of supra-fronto-orbital bristles.
The white larvae, or maggots, are legless and may be up to 8 mm in length. Pupal length is about 4 mm and adults range from 3 to 5 mm, approximately two-thirds the size of a housefly. The wingspan of Oriental fruit flies, which have a body length of 6 to 8 mm, have a wingspan of 5.3 to 7.3 mm. Medflies, being slightly smaller in body size, probably have slightly shorter wingspans. (California Department of Food and Agriculture, 2005; Teparkum, 1998; Thomas, et al., 2001)was not available, but can be extrapolated from the wingspan of similar species.
Medflies undergo a complete metamorphosis, beginning life as larvae and transforming into completely different-looking adult fruit flies. Females lay their eggs approximately 1 mm beneath the skin of host fruit. Although each female lays only 2 to 10 eggs in a given fruit, multiple females may lay their eggs in the same location, so that the slim, smooth, white eggs, about 0.1 cm long, may be clustered together in a single spot of seventy-five or more.
After 1.5 to 3 days (longer if the temperature is lower) the eggs hatch. The larvae carve tunnels, eating their way through the fruit. Larval life may last a mere 6 to 10 days (when temperature is around 25ºC). Along with temperature, the type of host fruit affects the length of the larval stage. In citrus fruits, 14 to 26 days may be required to reach pupation. Development in a green peach is completed in 10 to 15 days.
There are three larval stages, or instars. In the first, larvae are slender, cream colored, translucent, and about 0.1 cm long. In the second instar, larvae are partly transparent, revealing the fruit in the gut. By the third instar, larvae are opaque white and 0.6 to 0.8 cm long. These larvae can be distinguished from other fruit fly larvae by their thoracic spiracles, with 7 to 11 small protruding tubules.
Most larvae begin to pupate at sunrise, an inch or two into the soil. The pupal stage lasts from 6 to 13 days at around 24.4ºC. This range significantly increases (possibly to about 19 days) when the temperature drops to around 20.5ºC. The pupal stage is resistant to temperature extremes and dessication, so it may last much longer if conditions are not right for emergence. It is typical for the new adult medflies to surface on warm mornings. At this early adult stage, they are capable of flying short distances, and may disperse further distances via the wind. (Mau and Kessing, 1992; Thomas, et al., 2001)
Female medflies are fussy about their mates. Though the basis of a female's choice is not entirely understood by scientists, characteristic communications between the sexes are thought to play a role.
Male medflies claim their mating ground territories on individual leaves by depositing a pheromonal substance from the tip of the abdomen to the leaf. In addition, the male emits sounds by rapidly vibrating his wings while perched on the underside of his leaf.
Females watch this behavior from a distance of about 6 to 10 cm then begin to approach the male if he is deemed acceptable. As the female nears (within 3 to 5 mm) the male’s rapid wing flapping switches modes to what is called “fanning” in which he moves forward and backward, possibly to better direct the pheromones at the female. The male then proceeds with a side-to-side head motion. Slow motion analysis of the courtship shows female responses to the calling male. These inconspicuous responses, all occurring within 0.04 to 0.16 seconds, include touching the male with her head or front legs, jumping towards the male, short wing vibrations, and stretching just after mounting. A female may reject a male at any stage of the courtship sequence.
Males seek multiple mates (polygyny), whereas females tend to remate only if the initial mating was with a sterile male. ("Acoustic Trap for Female Mediterranean Fruit Flies", 2004; McPheron and Steck, 1996; Thomas, et al., 2001)
Adult medflies reach sexual maturity approximately five days after emerging from the pupal stage. Copulation occurs at any time of the day and both sexes are sexually active throughout the entire day. Medflies in tropical regions (warm temperatures year round) are capable of year-round breeding. A female medfly may lay up to 22 eggs per day, and possibly 800 eggs during her lifetime, though 300 is more typical. Because new eggs are constantly made throughout a female’s adult life, fecundity, or the number of eggs laid, is largely a function of the female’s lifespan. ("Acoustic Trap for Female Mediterranean Fruit Flies", 2004; Mau and Kessing, 1992; Thomas, et al., 2001)
Medflies do not provide care for their offspring after eggs have been laid. However, females do invest some resources in each egg, providing young with the nutrients and energy needed to hatch out as larvae.
Sources differ on the maximum lifespan of adult medflies, it may be six months or a year, though they agree that cool conditions with abundant food and water are necessary for the flies to survive this long. Most live much shorter lives, and in most populations at least half are dead in less than 60 days. On a normal diet of sugar and protein in laboratory settings, females tend to outlive males by approximately 1.5 days. (Carey, et al., 2002; Mau and Kessing, 1992)
Most information pertaining to the behavior ofdeals with reproduction, and is therefore reported in the Reproduction sections.
These flies are usually sedentary, staying in the same area as long as there is fruit present to serve as food and egg-laying sites. They can be dispersed by the wind at least a mile (1.6 km). (Thomas, et al., 2001)
There is little information available on home range sizes for medflies. There is at least some territoriality, with male medflies claiming their mating territories on individual leaves.
Male medflies use chemical, visual, acoustic, and behavioral (e.g. wing waving) signals in their sexual communication with females. See “Reproduction: Mating Systems” for information on both male-female and male-male (marking of leaves with chemical to stake out mating ground territory) communication. In addition to these communication pathways, it is likely that some tactile communication occurs during mating itself. (Thomas, et al., 2001)
Among the Tephritidae, medflies are the most polyphagous species. This means that they feed from the widest variety of host-fruits. Over 200 types of fruits and vegetables have been recorded as hosts for this parasitic species. Species consumed include fruits of the following plant families: Anacardiaceae, Cucurbitaceae, Loganiaceae, Meliaceae, Oleaceae, Podocarpaceae, Rosaceae, Rubiacaea, Sapotaceae and Solanaceae. Though preferences differ geographically, thin-skinned, slightly hard, ripe, and succulent fruits are desirable.
Adult (mature) and larval (immature) stages differ in their feeding habits. As mentioned under “Development”, larvae eat their way through the fleshy host fruit. At this immature stage, nutrition is essential and will determine adult size, time of development, and the percentage of larvae that emerge. Studies have shown that diets with higher concentrations of glucose and sucrose lead to better development than those containing high starch or maltose concentrations. Adult medflies require carbohydrates from the juices of ripe fruit, and protein from bird feces and decomposing fruit. Adults feed in mid-morning and late afternoon.
Adult medflies prefer the portion of the fruit in which there is more nutritive value. For example, the lower portions of orange and papaya fruits contain the bulk of the nutrition. If placed on the top portion of these fruits, a medfly will move to the lower part. In contrast, flies placed on the lower portion of the fruit remain there to feed. (California Department of Food and Agriculture, 2005; Demirel, 1999; Mau and Kessing, 1992; Thomas, et al., 2001)
These flies have no obvious structures or behaviors that are specifically related to defense against predators.
Medflies are attached by many parasitoid wasps. Some wasps (such as Diachasmimorpha tryoni and Diachasmimorpha longicaudata) are capable of hearing the larvae eating their way through the fruit. The wasp uses its ovipositor to inject an egg into the maggot. During the fly's pupation, the wasp larva will eat its host, killing the developing fly and emerging from the pupal case as an adult.
Many generalist predators of insects, such as ants, spiders, mantids, and assassin bugs will attack fruit flies. Birds, including chickens, will attack the larvae as they emerge from fruit, and some soil nematodes attack the larvae as the burrow and pupate. (Dekker and Messing, 2005; Adams, 1994; Dekker and Messing, 2005)
In their natural environment, these flies are parasitic on host plants, but are not often harmful to plant populations. They may reduce seed dispersal by spoiling fruit, but they don't necessarily prevent seed germination. They are prey for a wide variety of insect predators and parasites. They are much more significant in agricultural ecosystems, where they can be a major pest of fruit crops (see below). ("Common Pests of Summer Fruit in Western Australia", 2003; Gillespie and McNeil, 1998)
There are no known positive effects ofon humans.
Of all true fruit flies, medflies are the most rampant pest, attacking practically all with a fleshy fruit species. Economically, medflies impact humans by damaging crops and making the fruit unmarketable.
Fruit-growers and their governments around the world spend millions of dollars a year trying to control this pest and prevent it from spreading to new locations. ("Common Pests of Summer Fruit in Western Australia", 2003; International Atomic Energy Agency, 2003; Mau and Kessing, 1992)
This species is abundant around the world, and not considered in need of conservation. It is a pest, and the target of strong efforts to reduce its abundance and distribution.
Becausehas such negative impact on agricultural economies around the world, research into cotrol of this species is widespread. An important step in limiting crop damage inflicted by medflies is field sanitation. This involves destroying unmarketable and infested fruits, burying them one meter under soil with lime to kill any larvae present in the fruit. Also, reducing food sources (i.e. keeping the quantity of ripe fruit to a minimum) through weekly harvestings is helpful. In areas of severe infestation, further techniques are needed to eliminate medflies.
Insecticides are used, but can be ineffective since egg-laying takes mere minutes. Although the chemicals kill the adult pests, they often work only after eggs have been laid. Bait insecticides containing proteinaceous liquid attractants encourage females to feed. Such females may die before oviposition, reducing crop damage caused by larvae. Disadvantages of insecticide use include: residues in food, soil and water pollution, and the evolution of resistance to pesticide in medfly populations.
Releasing parasitoids (such as the wasps mentioned under “Predators”) is another method of control that may be employed. Research conducted in Hawaii showed that approximately twenty thousand wasp parasitoids (Diachasmimorpha tryoni) per square kilometer per week provided effective medfly suppression.
One of the most successful techniques of control, especially in combination with the release of parasitoids, is the release of sterile males. These sterile males mate with wild females who, in turn, produce infertile eggs.Such eggs do not hatch into destructive larvae. Difficulties in the production of sterile males have limited the utility of this method. (International Atomic Energy Agency, 2003; Mau and Kessing, 1992; McPheron and Steck, 1996; Thomas, et al., 2001)
There is sometimes confusion between C. capitata and other species of "true fruit flies" (family Tephritidae) and Drosophila melanogaster, the "fruit fly" that has been widely used in genetic research (along with other species of Drosophila). Despite the similar common names, Drosophila is in a different family, the Drosophilidae, and is not a significant agricultural pest. The Drosophila species that feed on fruit feed mainly on yeasts and other microbes that grow on decaying fruit, not on the fruit itself. They may be a household nuisance, but unlike and other tephritids, they don't damage intact fruit.
George Hammond (editor), Animal Diversity Web.
Amy Allen (author), Kalamazoo College, Ann Fraser (editor, instructor), Kalamazoo College.
Nancy Shefferly (editor), Animal Diversity Web.
Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
living in the southern part of the New World. In other words, Central and South America.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
uses sound to communicate
living in landscapes dominated by human agriculture.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
having a worldwide distribution. Found on all continents (except maybe Antarctica) and in all biogeographic provinces; or in all the major oceans (Atlantic, Indian, and Pacific.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
union of egg and spermatozoan
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
an animal that mainly eats fruit
An animal that eats mainly plants or parts of plants.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
fertilization takes place within the female's body
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
having the capacity to move from one place to another.
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
the area in which the animal is naturally found, the region in which it is endemic.
islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.
found in the oriental region of the world. In other words, India and southeast Asia.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death
chemicals released into air or water that are detected by and responded to by other animals of the same species
having more than one female as a mate at one time
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
scrub forests develop in areas that experience dry seasons.
breeding is confined to a particular season
remains in the same area
offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.
reproduction that includes combining the genetic contribution of two individuals, a male and a female
mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
movements of a hard surface that are produced by animals as signals to others
uses sight to communicate
breeding takes place throughout the year
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Adams, S. 1994. "Putting the bite on Caribbean fruit flies" (On-line). Accessed November 07, 2005 at http://www.ars.usda.gov/is/AR/archive/key2.htm.
California Department of Food and Agriculture, 2005. "Mediterranean Fruit Fly Pest Profile" (On-line). Pest and Disease Information. Accessed October 10, 2005 at http://www.cdfa.ca.gov/phpps/pdep/mediterranean_ff_profile.htm.
Carey, J., P. Liedo, L. Harshman, Y. Zhang, H. Mueller, L. Partridge, J. Wang. 2002. Life history response of Mediterranean fruit flies to dietary restriction. Aging Cell, (2002) 1: 140-148. Accessed November 13, 2005 at http://anson.ucdavis.edu/~mueller/agingcell.pdf.
Copeland, R., R. Wharton, Q. Luke, M. Meyer. 2002. Indigenous Hosts of Ceratitis capitata (Diptera:Tephritidae) in Kenya. Annals of the Entomological Society of America, 95/6: 672-694. Accessed November 12, 2005 at http://www.bioone.org/bioone/?request=get-document&issn=0013-8746&volume=095&issue=06&page=0672.
Dekker, L., R. Messing. 2005. "Introduction to Managing Fruit Flies in Hawai'i" (On-line). http://www.extento.hawaii.edu. Accessed November 12, 2005 at http://www.extento.hawaii.edu/kbase/reports/fruit_pest.htm.
Demirel, N. 1999. "Behavioral Paradigms in the Mediterranean Fruit Fly, Ceratitis capitata (Weidemann)" (On-line). Accessed November 07, 2005 at http://www.colostate.edu/Depts/Entomology/courses/en507/papers_1999/demirel.htm.
Gillespie, P., B. McNeil. 1998. "Ceratitis capitata (Weidman)" (On-line). Fruit Flies of New South Wales. Accessed October 10, 2005 at http://www.agric.nsw.gov.au/Hort/ascu/fruitfly/ceratiti.htm.
Hunt, M., E. Roux, R. Wood, A. Gilburn. 2002. The effect of supra-fronto-orbital (SFO) bristle removal on male mating success in the Mediterranean fruit fly (Diptera: Tephritidae). Florida Entomologist, 85: 83-88. Accessed October 12, 2005 at http://www.bioone.org/bioone/?request=get-abstract&issn=0015-4040&volume=085&issue=01&page=0083.
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McPheron, B., G. Steck. 1996. Fruit Fly Pests: A World Assessment of Their Biology and Management. Delray Beach, Florida: St. Lucie Press.
National Agricultural Pest Information System, 1993. "Fact Sheet for Fruit Flies" (On-line). Pest Tracker. Accessed October 10, 2005 at http://ceris.purdue.edu/napis/pests/misc/fff.txt.
Plácido-Silva, M., F. Zucoloto, I. Joachim-Bravo. 2005. Influence of protein on feeding behavior of Ceratitis capitata Wiedemann (Diptera:Tephritidae): comparison between immature males and females. Neotropical Entomology, 34: 539-545. Accessed October 12, 2005 at http://www.scielo.br/scielo.php?pid=S1519-566X2005000400002&script=sci_arttext&tlng=en.
Teparkum, S. 1998. "Pests of Mango" (On-line). Accessed October 10, 2005 at http://www.ento.vt.edu/Fruitfiles/mangoIPM/mangoIPM.HTM#Oriental%20fruit.
Thomas, M., J. Heppner, R. Woodruff, H. Weems, G. Steck. 2001. "Featured Creatures" (On-line). Accessed October 10, 2005 at http://creatures.ifas.ufl.edu/fruit/Mediterranean_fruit_fly.htm.