How respiratory structures vary with, or are constrained by, an animal's environment is of great importance to see the differences in evolutionary development and for comparative physiology hypotheses.

It is challenging to investigate the respiratory structures of insects because they are so small, therefore only a handful of species have been examined. The analytical process in several methods that have been used is lethal and destructive and takes a lot of time and work.

In this study researchers explored and tested a different approach to measuring tracheal volume using X-ray micro-tomography scanning on living, sedated larvae. This were done at the CAF CT Scanner Facility on Stellenbosch campus. Novel data on the resistance of the larvae to the radiation dose absorbed during X-ray micro-tomography scanning are provided. By comparing how tracheal dimension (reflecting metabolic supply) and basal metabolic rate (reflecting metabolic demand) increase with mass, the study showed that tracheal oxygen supply capacity increases during development at a comparable, or even higher rate than metabolic demand.

The study provides methodological insights and novel biological data on key issues in rapidly quantifying insect respiratory anatomy on live insects.

Image: X-ray micro-tomography images of larvae of the beetle Cacosceles Newmannii.

• The article  'Using µCT in live larvae of a large wood-boring beetle to study tracheal oxygen supply during development ' was published in Journal of Insect Physiology (2021; 130: 104199) and is available online at  https://pubmed.ncbi.nlm.nih.gov/33549568/

Media requests:

Prof Anton du Plessis

E-mail: anton2@sun.ac.za

Prof John Terblanche

E-mail: jst@sun.ac.za

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