Flight system morphology and minimum flight temperature in North American cicadas (Insecta: Hemiptera: Cicadidae).

Thermal responses in cicadas have been studied for many years. The minimum flight temperature (MFT) does not show the same relationship to habitat and behavior as other thermal responses. We measured live mass, wing length, wingspan, wing area and wing loading in an attempt to correlate these morphological parameters to the MFT. We analyzed both intraspecific (in Magicicada cassinii (Fisher, 1852)) and interspecific relationships of the wing morphology and the ability of the cicadas to fly in a large number of North American cicada taxa (n=119). A total of 109 species and 10 subspecies from 17 genera, six tribes, and three subfamilies including all major North American habitats were studied. Analyses show that wing morphology (wing length, wingspan, wing area and wing loading) scales to body size as predicted by geometric similarity (all P<0.0001) for all species and wing area and wing loading (both P<0.0001) in M. cassinii. Mass (P=0.0105), wing length (P=0.0006), wingspan (P=0.0006), wing area (P=0.0055), and wing loading (P=0.0455) all demonstrate a significant correlation to MFT between species, as would be predicted by aerodynamic theory, but not within species. However, the low correlation coefficients suggest the flight system has minimal influence on the MFT of cicadas. Specific physiological adaptations appear to be responsible for the between species variability in MFT rather than being the result of modifications to the flight system morphology.