Published data are collected here on the developmental zero point of various species of insects, which was obtained from the relation between temperature and the duration of development applying it to the theory of total effective temperature. Many collected values are listed in Table 1, where insects are listed in alphabetical order.
Frequency distribution of the developmental zero point is like a normal curve (Fig. 1), the mean of which falls at about 11°C. Maximum temperature obtained was 19.5°C and minimum one was -1.1°C. The zero points in the species of Lepidoptera or Hemiptera are somewhat lower than those of Hymenoptera or Diptera (Fig. 2 and Table 2). Even in the same species, the different value of it is shown by the differences of ecological race, sex, developmental stage and environmental condition.
Comparative magnitude of the developmental zero in each successive developmental stage is not constant and takes various combinations as shown in Table 3.
This is also true in each instar of the larval stage.
Interesting ecological implications are shown in the comparison between the developmental zero points in both species of prey and predator or host and parasite (Table 4) and in the comparison of it among closely allied species.
