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United States Department of Agriculture

Agricultural Research Service

Title: Examination of Frozen, Hydrated Mites Using Low Temperature Field Mission Scanning Electron Microscopy

Author
item OCHOA, RONALD

Submitted to: Electron Microscopy Society of America Proceedings
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 1, 2000
Publication Date: N/A

Interpretive Summary: More than 10,000 species of mites infect nearly every agronomic and horticultural plant important to agriculture. In the United States, these pests cause annual economic losses from decreased food, fiber, and ornamental production estimated to be in the billions of dollars. One problem facing scientists is their inability to observe the detailed structure of mites and to distinguish those that are harmful from those that are not. The current study describes a procedure that freezes mites so that they can be oberved with a very powerful microscope known as a field emission scanning electron microscope. With this instrument, scientists can observe the mites at magnifications of more than 20,000 times. This enables them to describe the detailed structure of new mites and to relate them to other forms. Examining mites in this way, provides scientists with information that can be used to identify potentially harmful mites and to help pest management specialists. In addition, this information will benefit the public by identifying new and potentially harmful species of mites before they are introduced into this country.

Technical Abstract: Because of their microscopic size and fragile nature, it has been estimated that less than ten percent of mite species are known to science. Recently, data from scanning electron microscopy (SEM) has been used to facilitate and complement the information that is obtained with a light microscope. However, the preparation techniques associated with SEM frequently prevent or compromise the results. This study evaluates the use of low temperatur field emission (LTFE) SEM to image mites. Results indicate that Cryofixation, which is associated with this technique, maintains the mites at their living/feeding sites. Furthermore, the turgor of the specimens, including eggs and soft bodied species, is also maintained. The structure of delicate features, such as setae, which are subject to mechanical damaged during chemical fixation, dehydration and drying, are well preserved. Field emission SEM, which provides useful magnification beyond that attainable with a conventional SEM, also enables resolution of ultrastructural features, such as pores on the surface of the solenidia. These advantages indicate that LTFESEM is an important technique that can provide complementary data for taxonomic descriptions of mites.

Last Modified: 8/19/2014
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