The effect of temperature on egg development in Zygoptera: a preliminary discussion

An analysis of the limits of tolerance for egg development in Odonata has been discussed in relation to two of the mathematical formulations available in the biological literature. Thresholds and limits are discussed in relation to the findings of RIVARD et al. (1975), MASSEAU & PILON (1982a), PILON (1982), and FRANCHINI & PILON (1983) on the egg development of E. boreale, E. ebrium, E. hageni, E. vernale and I. verticalis. From this review new thresholds for each species and new values for temperature summation are proposed. A speculative discussion on the development of larval stages in five summer Coenagrionids in the Lower Laurentides is presented. Egg development in these species takes place at the time when optimal weather conditions prevail in the field. However, a certain percentage of the larval population is probably not able to develop to the overwintering stage depending on the type of larval development to which they belong. As pointed out by TROTTIER (1971) an accurate knowledge of the effect of temperature on the rate of development of the different stages of Odonata is a necessary step towards an understanding of their ecology. This present paper simply stresses the importance of this statement and the need for further investigations.