Contributions of Microscopy to the Morphological Characterization of the Male Genitalia of Toxomerus politus (Diptera, Syrphidae)

Abstract

The study of insects has historically been linked to the development of microscopy. As techniques have improved, research into insect morphology can increasingly contribute to a better understanding of the structures and functions of the morphological characters of insects' three tagmata. We propose the use of methodologies applied in microscopy as a way of improving and facilitating the study of the morphological characters of fly genitalia. In addition, flies preserved in 70% alcohol were used to verify the feasibility of distinguishing ultrastructural characters in the spermatozoa, when not previously fixed for the preservation of morphological structures. We have shown that it is viable to enhance preservation of specimens using a scanning electron microscopy technique. In addition, the observation of genitalia using this technique, together with confocal laser scanning microscopy, enables better visualization, description, and understanding of the morphological characteristics of fly genitalia. We also noted, in analysis using transmission electron microscopy, that it is possible to recover and describe some morphological features of the ultrastructure of Toxomerus politus (Say, 1823) sperm, obtained from flies stored in 70% alcohol for a long period of time. Comparison between the methods used to investigate the structures of T. politus, observed after preserving the specimen, already demonstrates the importance of using appropriate methodology as a starting point for reliable results. The methodologies and techniques adopted in this work have the potential to be extrapolated to research into other species of flies and other insects in a broad context.