FOURIER-ANALYSIS OF WING BEAT SIGNALS - ASSESSING THE EFFECTS OF GENETIC ALTERATIONS OF FLIGHT-MUSCLE STRUCTURE IN DIPTERA

A method for determining and analyzing the wing beat frequency in Dipt era is presented. This method uses an optical tachometer to measure Di ptera wing movement during flight. The resulting signal from the optic al measurement is analyzed using a Fast Fourier Transform (FFT) techni que, and the dominant frequency peak in the Fourier spectrum is select ed as the wing beat frequency. Also described is a method for determin ing quantitatively the degree of variability of the wing beat frequenc y about the dominant frequency. This method is based on determination of a quantity called the Hinder, which is derived using data from the FFT analysis. Calculation of the H index allows computer-based selecti on of the most suitable segment of recorded data for determination of the representative wing beat frequency. Experimental data suggest that the Hinder can also prove useful in examining wing beat frequency var iability in Diptera whose flight muscle structure has been genetically altered. Examples from Drosophila indirect flight muscle studies as w ell as examples of artificial data are presented to illustrate the met hod. This method fulfills a need for a standardized method for determi ning wing beat frequencies and examining wing beat frequency variabili ty in insects whose flight muscles have been altered by protein engine ering methods.