|Joy, David - UNIVERSITY OF TENNESSEE|
Submitted to: Scanning
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 10, 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 determine how such factors as light, temperature, moisture and pressure are perceived by the mites. The current study describes a procedure that freezes mites so that they can be observed in 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 structures of mites and to postulate functions for these structures. Observations of mites with this microscope indicated one type of hair or seta may help the mite locate electro- or magnetic fields in their environment and thereby find a food source or avoid a predator. If this is true, perhaps artificial fields could be generated to confuse or disorient the mites and thereby reduce the damage that they cause to man and agriculture. Thus, this report will be used by scientists developing safe methods of controlling mites. The information may also benefit the public by identifying potentially harmful species of mites.
Technical Abstract: Mites, which are the second largest arthropod group after insects, contain over thirty types of specialized, external, hairs or microscopic setae that function as mechanoreceptors, chemoreceptors, thermoreceptors, hygroreceptors or photoreceptors. Recently, our laboratory demonstrated the advantages of using low temperature scanning electron microscopy (SEM) to distinguish and characterize the different types of setae found on mites. During this study, one highly specialized type of seta, known as a trichobothrium, exhibited regular and repeatable oscillations in the SEM as the frozen specimens were imaged. Subsequently, trichobothria were imaged in two other species and exhibited the same phenomenon. No other types of setae on the mites behaved in this manner. This study provides details on these observations and attempts to offer an explanation for the movement.