Commonly known as a fruit fly or vinegar fly, Drosophila melanogaster is one of the most prevalent flying insects. It is classified under the family Drosophilidae of the order Diptera. The distinguishing physical characteristics of fruit flies are brick-red eyes and brownish colored body with significant black rings along the length of the abdomen. The sexual dimorphism in this type of flying insect is very distinct; males are smaller, have an abdominal black patch, and sexcombs in the first leg. An adult fruit fly measures about 3 mm in length.
Drosophila melanogaster is widely used as a model organism in biology experiments. It is studied as a representing organism of eukaryotes. Be it in evolution, genetics, developmental biology, or pathology, fruit fly is used in several fields of science. Well, the specialty of this insect lies in its short life cycle, easy breeding, and production of large number of offspring (a female lays about 100 eggs per day).
Life Cycle of a Fruit Fly
In laboratory studies, a new generation of fruit flies can be obtained after every two weeks. With the advancement in genetic research, sequencing the genome of Drosophila has been completed and issued in the year 2000. Besides the small body size, there are only 4 pairs of chromosomes. Also, a lot of D. melanogaster mutant forms are produced and identified with different names. If you are a science student, you may be well acquainted with the life cycle of this insect.
The length of developing time (an egg maturing into an adult) varies with respect to the prevailing temperature, which is a characteristic of all cold-blooded insects. When kept at room temperature (77° F), a Drosophila egg requires 8.5 days to develop into an adult; whereas in temperatures higher than this, development time is more because of heat stress.
Egg: It is about 0.5 mm. A female may lay as many as 400 eggs in a favorable laying ground (for example, a decaying mushroom or a fruit). Within 24 hours of laying, the eggs hatch into the 1st star instar larvae. In room temperature conditions, this hatching time is as short as 15 hours.
Larva: The larval stage of this insect consists of three instars. Within 24 hours of hatching, the larva molts to develop into 2nd instar larva. Again after 24 hours (i.e., 48 hours after egg hatching), this larva molts, and matures to 3rd instar larva. During these stages, the larva loses its spiracles, mouth, and hooks.
Pupa: After 4 days of voracious feeding, the 3rd instar larva encapsulates itself inside a hard and dark-colored puparium. It is in this pupal stage, where the metamorphosis of D. melanogaster takes place, giving rise to wings and legs. At room temperature conditions, the duration of metamorphosis lasts for 4 days.
Adult: The adult D. melanogaster emerges through the operculum of the puparium. Within 8 - 12 hours of emergence, the female fly is receptive. Then, it mates with the male Drosophila for about 30 minutes, during which the male inseminates hundreds of sperms inside the female fly. The female stores the sperms, and uses them latter for laying eggs.
Since the maturation time of fruit flies differs with temperature fluctuation, it is obvious that their life span or longevity also varies with the surrounding environmental conditions. In general, the lifespan of Drosophila lasts for several weeks. And, considering the ease of breeding and caring, scientists all over the world agree that fruit flies will remain to be the most versatile model organism in biological science.