Fog-basking behaviour and water collection efficiency in Namib Desert Darkling beetles
In the Namib Desert fog represents an alternative water source. This is utilised by Darkling beetles (Tenebrionidae) that employ different strategies for obtaining the fog water.
Some dig trenches in the sand, while others use their own bodies as fog collectors assuming a characteristic fog-basking stance. Two beetle species from the genus Onymacris have been observed to fog-bask on the ridges of the sand dunes during fog events.
These beetles all have smooth elytra surfaces, while another species with elytra covered in bumps is reported to have specialised adaptations facilitating water capture by fog-basking. To resolve if these beetles also fog-bask, and if elytra covered in bumps are more efficient fog water collectors than smooth ones, we examined four Namib Desert beetles; the smooth Onymacris unguicularis and O.
laeviceps and the bumpy Stenocara gracilipes and Physasterna cribripes. Here we describe the details of the structures of the beetleelytra, their fog-basking behaviour, and determine how efficient they are at harvesting water from fog.
Results: The beetles differ greatly in size.
The largest P. cribripes has a dorsal surface area that is 1.39, 1.56, and 2.52 times larger than O.
unguicularis, O. laeviceps, and S.
gracilipes, respectively. In accordance with the earlier reports we found that the second largest O.
unguicularis is the only one of the four beetles that assumes the head standing fog-basking behaviour, and that fog is necessary to trigger this behaviour. No differences were seen in the absolute fog water collection efficiency by the different beetles.
However, data corrected according to the sizes of the beetles revealed differences. The better fog water harvesters were S.
gracilipes and O. unguicularis while the large P.
cribripes was the poorest. Examination of the elytra microstructures showed clear structural differences, but the elytra of all beetles were found to be completely hydrophobic.
Conclusions: The differences found in fog water harvesting efficiency by the dorsal surface areas of beetles with very different elytra surface structures were minor.
We therefore conclude that the fog-basking behaviour itself is a more important factor than structural adaptations when O. unguicularis collect water from fog.
Author: Thomas NorgaardMarie Dacke
Credits/Source: Frontiers in Zoology 2010, 7:23
Published on: 2010-07-16
Copyright by the authors listed above - made available via BioMedCentral (Open Access). Please
make sure to read our disclaimer prior to contacting 7thSpace Interactive. To contact our editors, visit our online helpdesk. If you wish submit your own press release, click here.
Social Bookmarking
RETWEET This! | Digg this! | Post to del.icio.us | Post to Furl | Add to Netscape | Add to Yahoo! | Rojo
|
|
