Fruit flies are any of the species of flies belonging to the taxonomic family Drosophilidae. They are also known as vinegar flies or pomace flies, and should not be confused with the family Tephritidae, which contain the true fruit flies. This family is most recognized for the species Drosophila melanogaster, which has been heavily studied in genetics, biological study, and developmental biology. Flies of the Drosophilidae family are characteristic for their infestation of leaves, fungi, flowers, slime fluxes, and fruit. They have a short life cycle, but reproduce rapidly to maintain their existence; they are a pest and a danger able to inflict tremendous damage on agriculture.
Physical characteristics in the Drosophilidae species range widely, but there are some that are typical of this family. All flies possess a minute anal cell in the wing, an incomplete subcostal vein with two breaks in it, and postocellar hairs; three of these quills usually rest on either side of the head.
The species Zaprionus indianus Gupta displays a unique pair of white stripes from the antennae to the end of the thorax on its dorsal side; two black lines of equal width straddle each white line. This species is a yellow color and around 3.5 mm in length.
The Drosophila suzukii is a light yellow to brown color, exhibits large red eyes, and in appearance seems very similar to the common fruit fly (Drosophila melanogaster). Females possess a bulky, toughened, jagged ovipositor, but no combs on their anterior feet like the males of this species. Both males and females display continuous black bands on their abdomen. Males are notable by the darkened section on the tips of each wing. This species averages 2-3mm in size.
The Rhagoletis indifferens, commonly referred to as the western cherry fruit fly is 5mm in size and on its wings exhibits a dark arrangement of bands.
Drosophilids deposit their eggs in flowers, fungi, fruit, sap fluxes, or decomposing vegetation by penetrating the surface and laying the egg(s) within. Characteristics in species differ in the number of eggs a female will oviposit at a time; some species lay just one, while others may lay hundreds. The sites where eggs are oviposited also vary. The international species, Drosophila busckii, has been known to breed from lettuce leaves in Victoria and leaves of pea plants in Japan. The Spotted Wing Drosophila uses her hefty, jagged ovipositor to puncture the skin of fruit and lays the eggs inside. These eggs will hatch and allow the larva to begin feeding on the fruit; this food source enables the maggots to develop. The steady consumption of the fruit causes it to spoil and become damaged, which can provide an opening for infection.
Drosophilidae species are formed of post-mitotic cells, possess a brief life span of one to several weeks varying on the climate temperature, and display incrementally ageing. Due to the short life cycle of fruit flies, they must rapidly reproduce to sustain their population. A Spotted Wing Drosophila may have between 10-15 generations in the year and 2-3 generations during the cherry season. This species is most active at 68oF; when temperatures surpass 86oF the adult males become sterile and activity is reduced. In a Drosophila culture media of a continuous 25oC, the Zaprionus indianus Gupta lived an average of 82 days for the males and 93 days for the females, with a maximum of 150 days. The females’ average number of offspring was 58, with a highest total being 105. The time span from egg fertilization to a grown adult was 19 days.
Drosophilids are seen as merely annoying flies because they infest decaying fruits, flowers, leaves and fungi. However, some species may inflict tremendous damage, like the Zaprionus indianus Gupta. This species infests 73 different kinds of fruit in its native region of Africa. Its presence in the western hemisphere has also been significant, especially in Brazil, where it is estimated to have caused a 50% commercial damage in the nation’s fig production. Drosophila suzukii is another species that has created economic havoc. This fly, commonly known as the Spotted Wing Drosophila, infests fresh fruits that include cherries, raspberries, strawberries, blueberries, and black berries. This species also damages boysenberries, nectarines, plumcots, and a range of Japanese plums because of the fruit’s soft flesh. Their infestation of such crops in California has produced a major agricultural issue.
The family Drosophilidae includes one of the most important organisms to scientific research, the Drosophila melanogaster. This minute fly is no more that 3mm long, but it has been researched for almost a century. Its small size, short life cycle, and ability to house in mass numbers, makes this fruit fly a practical organism for research.
The life cycle of the drosophila is just two weeks, which allows scientists to keenly observe the development of the fly. The eggs of the Drosophila melanogaster are approximately half a millimeter in length. A larva will emerge from the egg only a day after fertilization. The larva will rapidly molt as it eats. This molting continues until the drosophila transforms into an encased, stationary pupa, where it will spend the next four days altering its body into a winged adult. Within 12 hours of the newly reconstructed fly emerging it will become fertile.
The Drosophila melanogaster was initially studied in genetics, including for to the rules of inherent genetics and the relations between genes and proteins. However, the drosophila has been used more recently in the field of developmental biology, especially the embryonic and pupa development. The speed at which the embryo develops within the egg and the pupa’s rate of rebuilding the insect’s body into a winged form has captured the attention of scientific study. There are thousands of scientists at work today analyzing the small, yet fascinating Drosophila melanogaster.
- 98. Family DROSOPHILIDAE Neal L. Evenhuis and T. Okada, May 9, 2008.
- A quick and simple introduction to Drosophila melanogaster Gerard Manning, The Drosophila Virtual Library, July 12, 2008.
- Spotted Wing Drosophila, Drosophila suzukii: A New Pest in California J. Caprile, et al, University of California Integrated Pest Management,June 18, 2010.
- Drosophilidae, Wikimedia Foundation, Inc., September 26, 2010.
- Zaprionus indianus Gupta (Diptera: Drosophilidae), A Genus and Species New to Florida and North America Gary J. Steck, Florida Department of Agriculture and Consumer Services Division of Plant Industries, December 12, 2005.
- Identifying Drosophila suzukii Josh Vlach, Oregon Department of Agriculture, June 2, 2010.
- Spotted Wing Drosophila or Cherry Vinegar Fly Mark S. Hoddle, University of California Riverside - Center for Invasive Species Research, April 7, 2010.