Action de la témperature sur le développement embryonnaire de Enallagma hageni (Walsh) (Odonata: Coenagrionidae)

TEMPERATURE INFLUENCES ON EMBRYONIC DEVELOPMENT OF ENALLAGMA HAGENI (WALSH) (ODONATA: COENAGRIO- N1DAE) — Eggs of E. hageni were submitted to different constant-temperature regimes (10-35° C) under a constant photoperiod (16 h light). The lower threshold of development was estimated to be at 9.19° C according to Trottier’s formula (1971, Can. Ent. 103: 1671-1683), and the hatching threshold at 12.5° C. At temperatures of 35°C and higher no hatching was observed. The optimal temperature was 30° C with a mean hatching time of 9.2 days. The most favourable temperatures were estimated to be from 17.5-30.0° C. The results were compared with observations in nature.