Pre-flight warming up of maturing Aeshna mixta Latreille (Anisoptera: Aeshnidae)

It is shown that maturing A. mixta can use shivering as a pre-flight warming up strategy, which gives the insects the capacity to switch between pure ectothermy and a combination of ectothermy and endothermy. So far this has been evidenced in mature odonates only. Since this strategy opens the way to eocrepuscular flight in immatures, this may be a cue in explaining the role of twilight zone flight. For the first time the relationship between ambient temperature (T_) and shivering on the duration of the pre-flight period was investigated under natural conditions. The duration of shivering was negatively, but just not significantly, correlated with the ambient temperature. The duration of shivering and T_ did not effect the duration of the pre-flight period. Shivering intensity, however, significantly reduced the time prior to take-off. The observations suggest that abdominal shivering may represent part of an endothermic strategy.