Diversity of wing patterns and abdomen-generated substrate sounds in 3 European scorpionfly species

Functional Diversity of Vibrational Signaling Systems in Insects

Communication by substrate-borne mechanical waves is widespread in insects. The specifics of vibrational communication are related to heterogeneous natural substrates that strongly influence signal transmission. Insects generate vibrational signals primarily by tremulation, drumming, stridulation, and tymbalation, most commonly during sexual behavior but also in agonistic, social, and mutualistic as well as defense interactions and as part of foraging strategies. Vibrational signals are often part of multimodal communication. Sensilla and organs detecting substrate vibration show great diversity and primarily occur in insect legs to optimize sensitivity and directionality. In the natural environment, signals from heterospecifics, as well as social and enemy interactions within vibrational communication networks, influence signaling and behavioral strategies. The exploitation of substrate-borne vibrational signaling offers a promising application for behavioral manipulation in pest control.

Wing-waving behaviors are used for conspecific display in the Japanese scorpionfly, Panorpa japonica

Species of scorpionfly (Mecoptera) in the family Panorpidae perform wing-waving behaviors, whereby they rotate their front and rear wings at the same time. Previous studies have suggested that a male, which carries food for use as nuptial gifts for females, performs the wing-waving behavior when the male gives the gift to a female or competes with other males. However, when and how the wing-waving behavior occurs during a series of nuptial giftings and male–male competitions have not been investigated. Therefore, we here observed the role of wing-waving behavior during the processes of giving nuptial gifts and male–male competition in the Japanese scorpionfly Panorpa japonica in the laboratory and field. Unlike previous studies, only males performed wing-waving behavior toward females, while females did not exhibit the behavior in the wild. Also, males always performed wing-waving behavior before male–male competition. After a male–male competition, winner males continued wing-waving behavior, but loser males never performed the behavior against the winner male. A comparison of wing-waving behaviors before competitions between winner and loser males showed that the frequencies of wing-waving behaviors were higher in winner than in loser males. The present results suggest that the wing-waving behavior functions in the inter-sexual and intra-sexual selection in P. japonica. Digital video images related to the article are available at http://www.momo-p.com/showdetail-e.php?movieid=momo210513pj01a and http://www.momo-p.com/showdetail-e.php?movieid=momo210513pj02a and http://www.momo-p.com/showdetail-e.php?movieid=momo210513pj03a.

Hypothesis on monochromatic vision in scorpionflies questioned by new transcriptomic data

In the scorpionfly Panorpa, a recent study suggested monochromatic vision due to evidence of only a single opsin found in transcriptome data. To reconsider this hypothesis, the present study investigates opsin expression using transcriptome data of 21 species including representatives of all major lineages of scorpionflies (Mecoptera) and of three families of their closest relatives, the fleas (Siphonaptera). In most mecopteran species investigated, transcripts encode two opsins with predicted peak absorbances in the green, two in the blue, and one in the ultraviolet spectral region. Only in groups with reduced or absent ocelli, like Caurinus and Apteropanorpa, less than four visual opsin messenger RNAs have been identified. In addition, we found a Rh7-like opsin in transcriptome data derived from larvae of the mecopteran Nannochorista, and in two flea species. Peropsin expression was observed in two mecopterans. In light of these new data, we question the hypothesis on monochromatic vision in the genus Panorpa. In a broader phylogenetic perspective, it is suggested that the common ancestor of the monophyletic taxon Antliophora (Diptera, Mecoptera and Siphonaptera) possessed the full set of visual opsins, a Rh7-like opsin, and in addition a pteropsin as well as a peropsin. In the course of evolution individual opsins were likely lost in several lineages of this clade.