ENCM 21062 - Ecology Laboratory
Practical No: 09
Determination of the temperature tolerance range of a common ant species
(Oecophylla smaragdina - “Dimiya”)
Introduction
Shelford’s law of tolerance (Shelford, 1913) states that “not only may too little of
something be a limiting factor (as proposed by Liebig (1840)), but also too much of such
factors, e.g. heat, light, water can be limiting factors for organisms”. Therefore, an organism
has an ecological minimum and ecological maximum of such factors; the range between the
two values represents the limits of tolerance of any factor.
Learning outcomes
At the end of this session, students will be able to determine the air temperature tolerance
range of Oecophylla smaragdina workers.
Methodology
1. Study, sketch and describe the two experimental set ups and the control set-up and, other
requirements related to the experiment (air temperature within the beaker should only be
increased or decreased).
2. Keep the ants at each temperature for 10 minutes.
3. Record the number of dead individuals after each time period (preferably 10 minutes).
Initial No: 20 workers
Temperature
˚C
30
35
40
45
No. of dead
individuals after
10 minutes
Remarks
No. of dead
Temperature
individuals after Remarks
˚C
10 minutes
30
25
20
15
10
5
50
0
1
(Write any other observation on the status and behaviour of workers in the column for
‘Remarks’)
4. Show graphically the temperature tolerance range of the species.
Draw two graphs as follows.
(a) Temperature (˚C) along the X axis and mortality % along the Y axis.
(b) Temperature (˚C) along the X axis and survival % along the Y axis.
5. (a) Explain why the ants died with the increase or decrease of air temperature?
(b) What will be your finding in an open environment?
2