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Effects of the structure and composition of pheromone plumes on the response of the male almond moth, Cadra cautella
Abstract
The influence of the completeness of the blend and quantity of female produced pheromone on the response of male Cadra cautella (Lepidoptera: Phycitidae) was investigated. The threshold concentrations for initiation of pheromone-mediated behaviors are set solely by (Z,E)-9,12-Tetradecadienyl Acetate (the major component), but the presence of (Z)-9-Tetradecenyl Acetate (the minor component) at concentration levels above threshold increased the proportion of males engaging in intermediate and late in-the-sequence behaviors. The organization of male response to pheromone in C. cautella is in accordance with the component hypothesis. Investigation of the effects of blend and concentration of pheromone upwind flight orientation of C. cautella males demonstrated that males fly directly upwind not only to the blend that mimics the female gland extract, but also to an array of "wrong" or "sub-optimal" pheromone blends. The structure of the pheromone plume influences the flight pattern of C. cautella males flying to the complete blend at optimal dosages. Increase in plume size resulted in faster ground velocities, lower turning frequency, narrower turns, and reduced track angles. In short, increasing plume size results in faster and more direct upwind flight. Although changes in pheromone concentration had discernible effects on male upwind flight, concentration effects were smaller than the effects related to changes in plume shape. The internal structure among the plumes was manipulated to produce pulses of pheromone in turbulent plumes and no pulses in the homogeneous filament plume. When filamentous pheromone plumes were marked with smoke, in wind tunnel situations, we were able to monitor C. cautella males changing their inflight maneuvers in response to encounters with pheromone plumes. We explored two features determining the internal structure of the plume, the volume of "continuous" plumes, and the interval between several pulse durations. Males fly faster and straighter to intermittent pheromone plumes consisting of large puffs pulsed at high frequency. When pheromone puffs were delivered at low frequencies, moths responded to individual pulses by "locking on" and flying upwind after contact. The basis of the in flight pheromone-mediated behavior might be the individual responses to single pulses. (Abstract shortened by UMI.)
Subject Area
Entomology|Ecology|Physiology
Recommended Citation
Mafra-Neto, Agenor, "Effects of the structure and composition of pheromone plumes on the response of the male almond moth, Cadra cautella" (1993). Doctoral Dissertations Available from Proquest. AAI9408304.
https://scholarworks.umass.edu/dissertations/AAI9408304