Description/How to recognize a……..
An adult Drosophila melanogaster (common fruit fly) is yellow-brown (tan) in colour, and is only about 3 mm in length and 2 mm wide. It has a rounded head with large, red, compound eyes; three smaller simple eyes and short antennae. The female is slightly larger than the male. There are black stripes on the back surface of its abdomen, which can be used to determine the sex of an individual. Males have a greater amount of black colouring concentrated at the end of the abdomen. Like other flies, common fruit flies have a single pair of wings that grows from the middle segment of its thorax. Larvae are minute, white, and lack legs and a defined head (Miller 2014).
Getting around
Adult Drosophilds are able to fly. Larvae crawl to different part of their decaying host fruit/plant (Miller, 2014).
Communicating
Male Fruit fly sings to the females by initiating the wing vibration that normally generates courtship song (Clyne & Miesenböck, 2008).
Distribution
Widespread, their natural homes include those in the tropical regions of the old world (Africa, Asia and Europe), but common Fruit fly has been introduced to nearly all temperate regions of the world. They are also known to seek shelter in colder winter months because of their inability to withstand the colder temperature (Miller, 2014). The records in southern Africa include; north of Limpopo (unpublished record), coastal region of KwaZulu-Natal, suburbs of Johannesburg and Pretoria, Tanzania and along the coast of Mozambique (McEvey, 1988).
Habitat
Drosophila melanogaster is common in and near human settlements, whether this be large cities or farmyards and remote agricultural areas. This species often exist in large numbers at ripe fruit in kitchens, vegetable matter in bins and compost in gardens (McEvey 1988). Drosophila melanogaster breeds successfully in bananas, Ensete giletti. Other host plants used as breeding site of D. melanogaster include mangos (Mangifera indica), pawpaw (Carica papaya) and apple guava (Psidium gaujava). Several other fruit tree species of the African region have been shown to host D. melanogaster larvae (Keller 2007).
Food
Fruit flies utilise a variety of food and lives largely on plant material, including mostly rotting plants and fruit (adults), and unripe, slightly ripened and ripe fruit as well as fruit that has just started to decay (larvae) The larvae gradually develop on the decaying fruit, which they use as their main source of nutrition. Drosophila species are considered major pests in some parts of the world for this reason (Miller 2014).
Sex and Life cycles
Reproduction of this species is quick. A single pair of flies can produce hundreds of offspring within a couple of weeks; and the development of offspring is extremely dependent on temperature. The offspring become sexually mature within a few days. Male flies have sex combs on their front legs; they use the combs to grasp the female’s abdomen and genitalia and to spread their wings prior to mating. However, when these combs are removed it seems to have only a slight effect on mating success (Miller 2014).
Eggs of common fruit flies are place on fruit, and hatch into fly larvae, which instantly start consuming the fruit on which they were laid. The entire life cycle lasts approximately ten days at an optimal temperature (Miller 2014). Flies complete embryonic development as eggs before emerging as first instar larvae. The larvae eat, grow and molt through three instar stages before the larval stops crawling. Flies undergo transformation during the pupal stage and adult structures are formed. Upon completing transformation, an adult fly hatches (Kaleka, Kaur & Bali, 2019).
Family life
Eggs are usually laid in clumps on unripe or slightly ripened fruit; the larvae develop on a decaying fruit, and instantly start consuming the fruit on which they hatched. The larvae in the fruits tend to aggregate together, but they become solitary as they grow old. There are no parental care and no real family life (as they mate indiscriminately with any individual of the opposite sex) (Miller 2014).
The big picture
This species is widely used in scientific research to learn about traits that can be passed on from parent to child, the study of DNA, genes and characters, since it is relatively straightforward to disrupt or modify their genes. It is also used to model some human diseases and in the drug discoveries of such diseases (Miller 2014).
Friends and foes
As one of many animals that are low on the food chain, egg and larvae fall prey to different diseases, parasitoids and predators. Quite a high number of second instar larvae are attacked by a wasp species, though the host larva is not killed until after it has pupated. Drosophila melanogaster are infected by bacteria Wolbachia and Soiroplasma. These bacteria have the ability to manipulate Drosophila melanogaster’s ability to favor their own transmission, the Wolbachia-infected males and uninfected females result in the production of few to no offspring. Both Spiroplasma and Wolbachia can selfishly change host sex proportion through male killing in Drosophila, selectively killing the male offspring of infected females (Hamilton & Perlman 2013).
Smart strategies
These flies live for a very short time and have the capacity to produce lots of offspring. They utilise a wide variety of food sources and freely enter human settlements, which enables them to live almost anywhere in the world. These strategies ensure the survival of the species (Keller 2007).
Poorer world without me
Fruit flies should be considered as beneficial insects in that they eat rotting matter that might otherwise turn into a source of fungal or bacterial infection or attract more unwanted pests, such as mice and rats. They are important in that their digestive systems release the nutrients back into the soil. Other flies lay their eggs in dung so their worms can feed, breaking down the dung. These decomposers complete the food chain, releasing nutrients for plants, bacteria and fungi (Gardeners 2019).
People & I
Drosophila melanogaster is known to occupy storage facilities over winter seasons, where it can consume/ruin huge amounts of food. Common fruit flies are considered a pest in many areas (Miller, 2014).
Conservation status and what the future holds
The species has no special status (Miller, 2014).
Relatives
Drosophila is a species-rich genus; about 1 500 species have been described (Van der Linde et al. 2007). It is very difficult to differentiate between D. melanogaster and D. simulans, a closely related species; the difficulty appear as the pair being very similar in appearance and both can be found anywhere in the world (McEvey 1988). Drosophila sechellia is the only species that is highly specialised on a single food resource; the fruit of Morinda citrifolia, the rest can feed on a variety of food. Another very rare member of the subgroup is D. orena (Keller 2007).
Official Common Name: Common fruit fly
Scientific Name and Classification: Drosophila melanogaster Meigen, 1830
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Diptera
Family: Drosophilidae
Genus: Drosophila
Species: D. melanogaster Meigen, 1830
Scientific Name and Classification: Drosophila melanogaster Meigen, 1830
References and further reading
- Clyne, J.D. and Miesenböck, G., 2008. Sex-specific control and tuning of the pattern generator for courtship song in Drosophila. Cell, 133(2), pp.354-363.
- David, J.R., Lemeunier, F., Tsacas, L. and Yassin, A., 2007. The historical discovery of the nine species in the Drosophila melanogaster species subgroup. Genetics, 177(4), pp.1969-1973.
- Drosophila melanogaster Meigen, 1830 in GBIF Secretariat (2017). GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org on 2019-05-15.
- Gardener 2019, Fruit fly, viewed 13 January 2020, < https://www.gardeners.com/how-to/fruit-fly/7303.html>
- Hamilton, P.T. and Perlman, S.J., 2013. Host defense via symbiosis in Drosophila. PLoS pathogens, 9(12), p.e1003808.
- Kaleka, A.S., Kaur, N. and Bali, G.K., 2019. Larval Development and Molting. In Edible Insects. IntechOpen.
- Keller, A., 2007. Drosophila melanogaster’s history as a human commensal. Current Biology, 17(3), pp.R77-R81.
- McEvey, P., 1988. A key to Drosophilidae (Insecta: Diptera) collected in areas of human settlement in southern Africa. Journal of the Entomological Society of Southern Africa, 51(2), pp.171-182.
- Miller, C. 2014. “Drosophila melanogaster” (On-line), Animal Diversity Web, Viewed 13 January 2020, <https://animaldiversity.org/accounts/Drosophila_melanogaster/
- van der Linde, K., Bächli, G., Toda, M.J., Zhang, W.X., Katoh, T., Hu, Y.G. and Spicer, G.S., 2007. Case 3407: Drosophila Fallen, 1832 (Insecta, Diptera): proposed conservation of usage. Bulletin of Zoological Nomenclature, 64(4), pp.238-242.
Author: Remember Baloyi and Pholoshi Maake
Email: R.Baloyi@sanbi.org