Frankliniella occidentalis (Pergande): Comparison of spectral sensitivity with responses to colors during swarming and non-swarming behavior

Abstract

Frankliniella occidentalis response to color hue and intensity was tested in both field bioassays and electrophysiology of the thrips eye. Results of electroretinograms demonstrated that males and females have a double peak spectral efficiency in the ultraviolet near 365nm and in the green-yellow range at 540nm. Results of field tests suggest, based on density change relative to sex ratio change between behaviors, that there was a greater change in male behavior (i.e. density) than in female behavior. Higher densities of thrips were observed on blue, violet, white and yellow hues. Interactions between the UV and green photopigments and integration of visual stimuli within the central nervous system may allow for discrimination of blue and violet colors, that are at wavelengths between the two peaks. Because the peaks of spectral sensitivity and the relative efficiency are the same between sexes, and the relative rankings of density remains the same between behavior periods, the greater change in male versus female behavior may be the result of complex behavioral responses to many possible cues as yet undetermined.