Improvised, inexpensive and easier experiments for school students

1. BEHAVIOURAL ASSAY IN DROSOPHILA
Improvised, inexpensive and easier experiments for school students
Dr. G. NAGARAJ
Laboratory Assistant in Zoology
Regional Institute of Education (NCERT)
Mysore, Karnataka, India.
gnriem@gmail.com 09036865978

2. INTRODUCTION
• The behavioral responses of Drosophila to variety of sensory
stimuli like light, volatile and non-volatile chemicals,
temperature, humidity, gravity, and sound - have been measured
by others previously.
• Some of those assays are complex and costlier.
• Objective here is to design improvised, inexpensive and easier
experiments for the school students (IX-XII class) to assay the
behavior of Drosophila to various stimuli.

3. MATERIALS REQUIRED
1. Banana
2. Jaggery
3. Biscuits
4. Cotton
5. Sticker tape
6. A4 size transparency sheet
7. Black sheet
8. Cool drink bottle
9. Scale , scissors
10. Marker pen
11.Watch
12. Hair drier
13.Card board sheet
14. Thermometers
Pic.1. Materials Required

4. PREPARATION OF THE SETUP
1. Transparency sheet is rolled with diameter according to bottle neck
diameter.
2. Longitudinal edge of the roll/ tube is pasted with sticker tape.
3. Three such rolls are joined with tape.
4. This long tube is graduated/ marked at every 5cm with marker pen.
5. Another tube of 20cm long is made with black sheet with diameter
1cm wider than transparent tube.

5. COLLECTION OF FLIES
1. In a clean bottle put 2 or 3 pieces of
banana and keep it near window.
2. Next day we can see many flies
gathered in the bottle for food.
3. Plug the mouth of bottle with cotton.
4. Later, transfer these flies to empty
bottles and use them for experiments.
Pic. 2. Collection of flies

6. 1. Geotaxis assay
1. Plug the distal end of transparent tube with
cotton.
2. Remove cotton in the bottle and immediately fix/
insert the bottle mouth into proximal end of the
tube.
3. Keep this setup vertically (Pic.3) and observe
the movement of the fly.
4. Note whether flies settle down or goes up and
count the number & percentage of flies in
quarter of the tube (0-25, 26-50, 51-75& 76-100cm .
5. Also find out how much time they take to reach
25, 50,75cm and top.
6. Interpret your observation.
BEHAVIOURAL ASSAY
Pic. 3. Geotaxis assay

7. 2. Phototaxis assay
1. Previous experimental setup is kept horizontally.
2. Insert black tube on transparent tube and keep it in centre/at
distal end (Pic.4).
3. This setup makes two/third of tube 9in turn flies) exposed to light
and one/third is in dark.
4. Observe where flies settles whether in dark or light area.
5. Interpret your observation.
Pic. 4. Phototaxis assay

8. 3. Thermotaxis assay
1. Like previous experiment the setup is kept horizontally.
2. Insert a thermometer at the distal end and keep another one near
proximal end.
3. In the middle of the tube a partition board is fixed.
4. Near distal end keep a hair drier diagonally (Pic. 5) and switch it
on with medium hot/speed.
Pic. 5. Thermotaxis assay

9. 5. Hot air rises the temperature up to 5-10’c within 2-5 mins at the
distal half part of the tube.
6. Because of the partition board proximal part is not affected by hot
air and remains in room temperature.
7. This setup gives normal and warm climate (temperature) to flies.
8. 5-10’c higher temperature at distal half part is maintained by
switching on the hair drier every alternative minutes for 30 mins.
9. Observe the movement/ settlement of the flies for 30 mins.
10. Interpret your observation.

10. 4. Chemotaxis assay
1. Keep the setup (bottle & tube) horizontally.
2. Keep a piece of food item like banana/ jaggery/ biscuits etc. at the distal
end of the tube and plug the opening with cotton (Pic.6-8)
3. Observe the movement of the flies for 30 mins.
4. Note how much time the flies taken to reach 25, 50, 75 & food ; and which
food item attracts flies more.
5. Food items can be replaced with other volatile / non-volatile chemicals
and their effect on flies (movement) can be assayed.
Pic.6. Chemotaxis Pic.7 Jaggery Pic.8 Biscuits

11. Control setup
For all the above experimental setup, a control setup for each
assay have to be maintained and studied. Control setup is
nothing but similar to the experimental except the testing factor
i.e. black tube (darkness) of photostaxis, hair drier (heat) of
thermotaxis and biscuits or jaggery of chemotaxis. For geotaxis a
horizontal tube can be used as control. Compare the
observations of experimental with control.

12. CONCLUTION
“Science is not listening, it is doing”. In this
respect the proposed above improvised and low-cost
experiments will help the students (of IX to XII class)
to learn science better and go beyond text book. It is
known that “observation is the mother of research”,
such observational projects will also develop
research bent of mind among students. Further, these
experiments were also tested with V semester B. Sc.
Ed students of RIE, Mysore.

13. THANK YOU