When the Utility of Micro-Computed Tomography Collides with Insect Sample Preparation: An Entomologist User Guide to Solve Post-Processing Issues and Achieve Optimal 3D Models

Many techniques are used today to study insect morphology, including light and electronmicroscopy. Most of them require to specifically prepare the sample, precluding its use for furtherinvestigation. In contrast, micro-CT allows a sample to be studied in a non-destructive and rapidprocess, even without specific treatments that might hinder the use of rare and hard-to-find speciesin nature. We used synchrotron radiation (SR) micro-CT and conventional micro-CT to prepare3D reconstructions of Diptera, Coleoptera, and Hymenoptera species that had been processed with4 common preparation procedures: critical-point drying, sputter-coating, resin embedding, andair-drying. Our results showed that it is possible to further utilize insect samples prepared withthe aforementioned preparation techniques for the creation of 3D models. Specimens dried at thecritical point showed the best results, allowing us to faithfully reconstruct both their external surfaceand their internal structures, while sputter-coated insects were the most troublesome for the 3Dreconstruction procedure. Air-dried specimens were suitable for external morphological analyses,while anatomical investigation of soft internal organs was not possible due to their shrinking andcollapsing. The sample included in resin allowed us to reconstruct and appreciate the externalcuticle and the internal parts. In this work, we demonstrate that insect samples destined to differentanalyses can be used for new micro-CT studies, further deepening the possibility of state-of-the-artmorphological analyses.