Spatial orientation of the mould mite, Tyrophagus putrescentiae (Schrank) (Acarina: Acaridae), in the computer-programmed olfactory field

The attractiveness of food odor to the mould mite was demonstrated in the micro-locomotion compensator (MLC) as well as in a classical choice-chamber. The MLC has been developed for use in experiments on the orientation mechanisms of tiny animals. The positioning system of the MLC constantly returns a mite walking on a glass plate to the center of the apparatus by sliding the plate. A computer controlling the MLC logs the displacement of the plate, whose array defines the path of the mite. It also controls a micro solenoid-operated valve to generate odor cues in airflow over the mite. If the odor is generated by position in a virtual olfactory field created by the MLC, the mite would exert a similar olfactory response as in a real choice-chamber. In practice, odorous zones with attractant were defined on the glass plate in a checkered pattern, and the test animal was exposed to the odor while it stayed in the zones. Mites were effectively confined to the odorous zones in the virtual olfactory field, as well as in the real choice-chamber. The frequency of stays in the odorous zones positively correlated with the odor concentration to provide a reliable estimate of attractiveness using probit analysis.