Evolutionary relationships of courtship songs in the parasitic wasp genus, Cotesia (Hymenoptera: Braconidae).

Justin P Bredlau,Karen M Kester,Vivek Nityananda

doi:10.1371/journal.pone.0210249

Abstract

Acoustic signals play an important role in premating isolation based on sexual selection within many taxa. Many male parasitic wasps produce characteristic courtship songs used by females in mate selection. In Cotesia (Hymenoptera: Braconidae: Microgastrinae), courtship songs are generated by wing fanning with repetitive pulses in stereotypical patterns. Our objectives were to sample the diversity of courtship songs within Cotesia and to identify e underlying patterns of differentiation. We compared songs among 12 of ca. 80 Cotesia species in North America, including ten species that have not been recorded previously. For Cotesia congregata, we compared songs of wasps originating from six different host-foodplant sources, two of which are considered incipient species. Songs of emergent males from wild caterpillar hosts in five different families were recorded, and pattern, frequency, and duration of song elements analyzed. Principal component analysis converted the seven elements characterized into four uncorrelated components used in a hierarchical cluster analysis and grouped species by similarity of song structure. Species songs varied significantly in duration of repeating pulse and buzz elements and/or in fundamental frequency. Cluster analysis resolved similar species groups in agreement with the most recent molecular phylogeny for Cotesia spp., indicating the potential for using courtship songs as a predictor of genetic relatedness. Courtship song analysis may aid in identifying closely related cryptic species that overlap spatially, and provide insight into the evolution of this highly diverse and agriculturally important taxon.

Highlights

Acoustic signals are used by diverse groups of insects for species recognition, fitness displays, and courtship elicitation
In this study we describe the courtship songs of ten additional species of Cotesia, and use clustering to explore the relationships and patterns among songs
Eleven species of Cotesia were collected at different sites in the United States (Table 1); one additional species was from a published recording (C. marginiventris)

Summary

Introduction

Acoustic signals are used by diverse groups of insects for species recognition, fitness displays, and courtship elicitation. Songs used during insect courtship are generally stereotypical within a species and likely play a role in reproductive isolation. Courtship songs may be a useful identifying character, especially among cryptic or closely related species [1]. Songs of Drosophila species groups are species-specific and have been studied for evolutionary patterns [2,3,4,5]. Courtship song analyses have been used in conjunction.

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