8.1. Rate of development

Homeothermous organisms are warm blooded (mammals, birds)
Poikilothermous organisms are cold blooded (all invertebrates, plants, fishes, amphibians, reptiles)

Development of poikilothermous organisms depends on temperature, whereas development of homeothermous organisms is temperature-independent.

The rate of development can be measured by a reciprocal of the number of time units (e.g., days) that is required for completion of development. Rates of development can be estimated for the entire onthogenesis or for a specific stage. For example, if it takes 15 days for an insect to develop from egg hatch till pupation, then the rate of larval development is v = 1/15 = 0.0667.

Temperature (°C), t
Development time,
T
Development rate,
v = 1 / T
5
-
-
10
200
0.005
15
100
0.010
20
60
0.017
25
40
0.025
30
30
0.033
35
35
0.028

Here is the graph of development rate versus temperature:

In the temperature range from 10 to 30 (°C), development rate changes almost linearly with increasing temperature. At very low temperature there is no development, and at very high temperature development is retarded.

Alexei Sharov 12/5/98