Use of low-temperature field emission scanning electron microscopy to examine mites

Partly because mites are microscopic in size and fragile in nature, acarolo gists estimate that less than five percent of extant species have been taxo nomically described. Recently, data from conventional scanning electron mic roscopy (SEM) have been used to facilitate the descriptions and complement the information that has been historically obtained with the light microsco pe. However, the conventional preparation techniques associated with SEM fr equently prevent or compromise the results. This study evaluated the use of low-temperature field emission SEM to image mites and their hosts. Results indicated that a modified cryofixation procedure, which was associated wit h this technique, retained the mites at their living/feeding sites in natur al behavioral positions. Furthermore, the turgor of the specimens, even egg s and soft-bodied species, was also maintained. The structure and orientati on of delicate structures such as setae, which would be subjected to mechan ical damage during conventional chemical fixation, dehydration, and drying, were also preserved after cryofixation. Field emission SEM, which provided useful magnification beyond that attainable with a conventional SEM, also enabled resolution of ultrastructural features, such as tenent hairs on the empodium and pores on the dorsal surface that had not previously been obse rved. These advantages indicate that the low-temperature field emission SEM can provide important structural data that can be used to study the anatom y, morphology, and bioecology of mites.