Characterization of copulatory courtship song in the Old World sand fly species Phlebotomus argentipes

Abstract

Acoustic communication in the form of courtship and mating songs are often involved in reproductive isolation between species of Diptera, such as Drosophila, mosquitoes and sand flies. The patterns of courtship songs in New World sand fly species evolve quickly under sexual selection; and therefore, represent an important trait that can be used as a marker to study the evolution of species complexes and may aid identification of sibling species with a complex. The ability to identify vector species within species complexes is of critical importance for effective and efficient vector control programs. Species-specific song patterns seems to contribute to reproductive isolation in New World sand fly species, suggesting that auditory communication signals may be widespread among these important vectors of leishmaniasis. The main goal of the present study was to characterize the copulatory courtship song of Phlebotomus argentipes, an important vector of visceral leishmaniasis in the Old World. Ph. argentipes males produce acoustic signals during copulation and two types of songs were observed. The one we called primary song is a 'pulse song' with similar length and amplitude to the previously observed 'P1' pattern recorded in Brazilian populations of Lu. longipalpis s.l. The secondary song has 'sine song' characteristics and is quite different from any song produced by New World species. The discovery of this copulation courtship songs in Ph. argentipes supports the possibility that acoustic communication in sandflies might be more widespread than previously thought, including Old World species. Our results highlight the importance of further research on acoustic communication in the Ph. argentipes species complex and other Old World vectors of leishmaniasis.

Figure 1

Copulatory courtship song of Ph. argentipes. (A) General view of song trace showing primary followed by a secondary song trace, (B) Trace of a pulse-type primary song and (C) Trace of a sine song of the secondary song. Figures (B,C) show 1 second of song.

Figure 2

Song spectrogram of copulatory courtship song of Ph. argentipes. Pulses with similar length and amplitude compose the primary song and multiple harmonics with five different frequencies are evident in the secondary song.