Flying Scorpions?

Found a cool insect today at Gander Mountain:

Scorpionfly (Panorpa speciosa),

Gander Mt. FP, Lake Co, IL 5/29/2014

This interesting fellow is a Scorpionfly (Panorpa sp.), in the order Mecoptera. I think it's P. speciosa, but there are several other possibilities and they aren't especially easy to ID. The coiled abdomen that gives the group their name is only found in males. They're totally incapable of stinging, though -- that structure is used for mating.

Their mating system has inspired a surprising amount of research, given how infrequently I've managed to find the darn things. (This is my first for Illinois and my third ever scorpionfly.) The concept of fluctuating asymmetry (FA) has been around for some time. While the genes of most animals produce a bilaterally symmetrical result, those genes still have to work in a rather unforgiving environment. Genotypes that are better able to adapt to the surroundings during development should produce more symmetrical individuals, so FA becomes a measure of genetic quality.

This idea has been tested in other organisms -- for instance, Moller found that female Barn Swallows (Hirundo rustica) prefer more symmetrical males. (1) What makes Panorpa so interesting in this regard is that their mating system appears to be driven by pheromones rather than visual signals, so FA shouldn't be something directly selected for. However, Thornhill found that female Japanese Scorpionflies (P. japonica) prefer pheromones from males with low FA, providing strong support for the idea that FA is an honest signal of genetic quality. (2) The polygynous nature of their mating system helps with these sort of studies, (3) since sexual selection is based on differential mating success on the part of one or both sexes, and those differences are usually higher in polygynous species than in monogamous ones.

Actually finding life on another planet would be an amazing thing, and would give a lot of wonderful insights into evolution on Earth. But in the meantime, we don't have to worry about running out of things to learn right here in our own backyards.

(1) Moller, A. P. (1994). Sexual selection in the barn swallow (Hirundo rustica). IV. Patterns of fluctuating asymmetry and selection against asymmetry. Evolution, 658-670.

 

(2) Thornhill, R. (1992). Female preference for the pheromone of males with low fluctuating asymmetry in the Japanese scorpionfly (Panorpa japonica: Mecoptera). Behavioral Ecology, 3(3), 277-283.

 

(3) Sauer, K. P., Lubjuhn, T., Sindern, J., Kullmann, H., Kurtz, J., Epplen, C., & Epplen, J. T. (1998). Mating system and sexual selection in the scorpionfly Panorpa vulgaris (Mecoptera: Panorpidae). Naturwissenschaften, 85(5), 219-228.