Spectral mating preferences were examined in male Agrilus angustulus (Buprestidae: Coleoptera), a member of a taxon known for its high species diversity and striking metallic coloration. The spectral emission profile of a typical A. angustulus female displays low chroma, broadly overlapping that of the green oak leaves they feed and rest upon, while also including longer wavelengths. To pinpoint behaviorally significant spectral regions for A. angustulus males during mate selection, we observed their field approaches to females of five Agrilus planipennis color morphs that have greater chroma than the normal conspecific female targets. Agrilus angustulus males would initially fly equally frequently toward any of the three longest wavelength morphs (green, copper and red) whose spectral emission profiles all overlap that of typical A. angustulus females. However, they usually only completed approaches toward the two longest wavelength morphs, but not the green morphs. Thus, spectral preference influenced mate selection by A. angustulus males, and their discrimination of suitable targets became greater as these targets were approached. This increasing spectral discrimination when approaching targets may have evolved to allow female emissions to remain somewhat cryptic, while also being visible to conspecifics as distinct from the background vegetation and heterospecific competitors.
The authors declare no competing or financial interests.
M.J.D. developed concepts, designed experiments, performed experiments and data analysis, and prepared the manuscript. J.P.L. designed experiments and performed experiments to obtain color morphs. A.J.M. performed data analysis. G.C., L.S. and Z.I. developed concepts and assisted in insect location and experimentation T.C.B. developed concepts and revised the manuscript.
Funding was provided by the United States Department of Agriculture, Animal and Plant Health Inspection Service program supporting the Development of Detection Tools for Exotic Buprestid Beetles [12-8130-1430-CA].
All data are available through figshare: figshare.com/s/161e6cb4276511e5855e06ec4b8d1f61
Supplementary information available online at http://jeb.biologists.org/lookup/doi/10.1242/jeb.137885.supplemental
- Received January 22, 2016.
- Accepted June 29, 2016.
- © 2016. Published by The Company of Biologists Ltd