Environmental Turbulence

 

Turbulence in natural environments and its effect on flying insects


Wild insects perform flight behaviors in an aerial environment that is very different from an indoor laboratory.  All natural environments contain turbulent eddies, and the size and strength of these eddies varies enormously depending on height above the ground, surrounding vegetation, and atmospheric conditions.  Despite the profound influence that this complex, unpredictable aerial environment may have on flying insects, no studies to date have examined how turbulence affects insect flight performance.  Our work on rolling instabilities during forward flight in orchid bees (Combes and Dudley, 2009) has led us to look more closely at the aerial environment produced by wind tunnels and found in natural habitats.  We have measured how turbulence varies in tropical forests from ground level to the top of the canopy, and are developing techniques to reproduce the complex characteristics of natural air flow with open-air jets. 


While studying forward flight in orchid bees, we found that individual bees vary significantly in their ability to maintain stable flight in turbulent air.  Because many of the resources that orchid bees collect are found only in upper levels of the canopy where turbulence is high, this individual difference in flight performance could have important ecological implications, preventing certain individuals from collecting the wide variety of resources needed to survive and attract mates.  To determine whether this link between the aerial environment and flight performance plays a significant role in the foraging ecology of orchid bees, we are planning further studies to track the vertical and horizontal movements of bees after characterizing their capacity for maintaining stable flight in turbulent air.