Drosophila Research
Drosophila melanogaster is known generally as the common fruit fly.
This species is a model organism that is widely used for biological
research in studies of genetics, physiology, microbial pathogenesis and
life history evolution. It is typically used because it is a species that is
easy to care for, breeds quickly, and lays many eggs.
If you have been seeing small flies or gnats in your kitchen, they're
probably fruit flies. Fruit flies can be a problem year round, but are
especially common during late summer/fall because they are attracted to
ripened or fermenting fruits and vegetables.
Tomatoes, melons, squash, grapes and other perishable items brought in
from the garden are often the cause of an infestation developing indoors. Fruit flies are also attracted to
rotting bananas, potatoes, onions and other unrefrigerated produce purchased at the grocery store. This
fact sheet will explain how infestations originate and how they can be prevented in your home or place
of business.
Fruit flies are common in homes, restaurants, supermarkets and wherever else food is allowed to rot
and ferment. Adults are about 1/8 inch long and usually have red eyes. The front portion of the body is
tan and the rear portion is black. Fruit flies lay their eggs near the surface of fermenting foods or other
moist, organic materials. Upon emerging, the tiny larvae continue to feed near the surface of the
fermenting mass. This surface-feeding characteristic of the larvae is significant in that damaged or
over-ripened portions of fruits and vegetables can be cut away without having to discard the remainder
for fear of retaining any developing larvae.
Life cycle:
The developmental period for Drosophila melanogaster varies with temperature, as with many
ectothermic species. The shortest development time (egg to adult), 7 days, is achieved at 28 °C (82 °F).
Development times increase at higher temperatures (11 days at 30 °C or 86 °F) due to heat stress.
Under ideal conditions, the development time at 25 °C (77 °F) is 8.5 days, at 18 °C (64 °F) it takes 19
days and at 12 °C (54 °F) it takes over 50 days. Under crowded conditions, development time
increases,[8] while the emerging flies are smaller.[8][9] Females lay some 400 eggs (embryos), about five
at a time, into rotting fruit or other suitable material such as the medium in which we will use in class.
The eggs, which are about 0.5 millimeters long, hatch after 12–15 hours (at 25 °C or 77 °F). The
resulting larvae grow for about 4 days (at 25 °C) while molting twice (into 2nd- and 3rd-instar larvae),
at about 24 and 48 h after hatching. During this time, they feed on the microorganisms that decompose
the fruit, as well as on the sugar of the fruit itself. Then the larvae encapsulate in the puparium and
undergo a four-day-long metamorphosis (at 25 °C), after which the adults emerge.
Females become receptive to courting males at about 8–12 hours after emergence. Males perform a
sequence of five behavioral patterns to court females. First, males orient themselves while playing a
courtship song by horizontally extending and vibrating their wings. Soon after, the male positions itself
at the rear of the female's abdomen in a low posture to tap and lick the female genitalia. Finally, the
male curls its abdomen, and attempts copulation.
Things you need to research:
1. How to determine the sex of a fruit fly
2. Best mating techniques
3. Transfer techniques
4. Proper storage techniques
5. How to anesthetize a fly colony.
6. How to make nutrient medium.
7. Life cycle of Drosophila
8. Disposal techniques
9. Genetic traits that are easily identifiable.
10. Past research and data.
11. How to calculate recombination frequency.
12. Much, much more……
Things to get done prior to project:
1.
2.
3.
4.
What question(s) are you asking
What is your hypothesis?
How many traits will you look at? Why?
You and your group will need to identify what traits are on the same chromosome or different
chromosomes.
a. How do you figure that out?
b. What data do you need to collect?
c. How many flies do you need to cross?
d. How many offspring do you need to count?
e. Do you need to perform a “Test Cross”?
5. Do you have enough time to complete this project (The project is not due until April 30th).
Project requirements: (see “Formal Lab reporting Guidelines” and “Lab grading rubric”)
1.
2.
3.
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6.
Completed project must be typed and your best work.
Each group turns in one project paper with both of your names on the project.
A title page
Have your project proof read before you turn it in.
Use proper grammar and talk in the best scientific language possible.
Introduction to project with question(s) asked, your hypothesis, and independent variables
identified.
7. Detailed material list
8. Each procedure written out completely
9. Complete results section including:
a. Properly labeled figures
b. Appropriate data tables
c. Chromosomal banding figure
10. Conclusion:
a. Remember to refer to your results
b. Answer any questions asked
c. What happened?
d. What went wrong?
e. What would you do different next time?