Doctoral Dissertations


J. C. Webb

Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Biosystems Engineering

Major Professor

John J. McDow

Committee Members

John I. Sewell, Walter L. Green, Smith Worley


Investigations were made to isolate, analyze, and identify the specialized sound produced by the male Caribbean fruit fly, Anastrepha suspensa (Loew), before pair formation and to determine if this sound is used as one mode of communication in the fly's sexual behavior. Three other sounds were identified and related to specific behavioral activities, These experimental data were to provide information on one of several factors that is needed to develop effective control methods for this and other closely related insect species. These sounds were recorded with the flies located in an anechoic chamber. Calibrated condenser microphones were used as the transducers to detect these sounds, to convert them to electrical signals, and to transfer them to instrumentation located outside of the anechoic chamber. After the sound pressure level was recorded, the data were stored on magnetic tape for later analysis and identification. The data were analyzed for frequency, waveform, and pulsed information. A power spectral density or a frequency spectrum was calculated and plotted for each sound signal on a real—time spectrum analyzer and an x—y recorder. The power spectral density and the frequency spectrums were compared for each sound signal for similarities and differences. A bioassay test system was designed and constructed to measure the response of both the males and the females to the reproduced calling sound alone or in combination with pheromone extract. The test insects were allowed to move toward the treatment, away from the treatment, or to remain in the entrance cell. Four sounds from the male flies were isolated and identified and each related to a specific behavioral activity; these activities are flight, aggression, premating, and calling. Each of these sounds was found to contain different information and each has its own distinct frequency signature. The calling sound was the only one to contain pulsed information. The pulse duration ranged from 0.04 to 21 seconds, with 60 percent of the pulse durations less than 0.50 seconds and 85 percent less than 0.75 seconds. The males did not respond to other calling males or to the reproduced calling sound either alone or in combination with pheromone extract. The females, eight to thirteen days old, responded to calling males, pheromone extract, and reproduced calling sound plus pheromone extract, but did not respond to sound alone. The response of the younger flies, six to eight days old, was significantly greater to sound plus pheromone extract than to pheromone extract alone. The techniques developed in the research for obtaining frequency signatures of the acoustical properties for specific insect activities show promise of becoming a very important tool for measuring insect quality. Such a tool would be a true asset to research scientist as a measure of quality control for both laboratory reared and mass reared insects. These frequency signatures could also be useful as a taxonomic tool in identifying other species of Tephritid fruit flies.

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