Natuurtijdschriften

Toegang tot tijdschriften over de Nederlandse natuur

The life history of Aeshna mixta seems to be subject to thermal conditions acting during the embryonic stage. Three aspects should be considered. 1. – Completion of embryonic diapause. An exposure of the eggs at 10°C for 10 to 15 weeks before return to 20°C must be considered as the thermal optimum for performing the diapause development. 2. — Synchronization of hatching. The minimal period of exposure to low temperatures is 15 weeks. After that time 94% of eggs hatch within 5 days. 3. – Number of larval instars. The post-embryonic development may involve 9, 10 or 11 larval Instars, each of these development types being determined ab ovo. A relatively short embryogenesis (100 days) induces hatching of larvae which develop within a rather short time (2/3 of type 9, 1/3 of type 10), whereas an about two times longer embryogenesis causes the hatching of larvae which develop slowly with a higher number of instars (4/5 of type 10,1/5 of type 11).