A comparison of the courtship and mating behavior of three species ofNasonia (Hymenoptera: Pteromalidae)

The parasitic waspNasonia vitripennis (Hymenoptera: Pteromalidae) is the subject of numerous genetic, evolutionary, ecological, and ethological studies, particularly relating to sex-ratio evolution, non-Mendelian inheritance, courtship behavior, and speciation. Here we describe the courtship behavior of two sibling species(N. longicornis andN. giraulti) and compare their courtship to that ofN. vitripennis. Courtship behavior ofNasonia males includes mounting of females, orientation to the female's head, and a repeated series of stereotypic movements, including head nods, mouthpart extrusions, antennal sweeps, and wing vibrations. Females signal receptivity by lowering their antennae in synchrony with opening their genital orifice. After copulation, males engage in brief postcopulatory displays. All three species have the basic components described above. However, although the three species are quite similar morphologically, there are distinct differences in courtship displays. Notable differences include the length of courtship cycles, the absence of a ritualized antennal sweep prior to the first cycle invitripennis, additional head nods and ritualized foreleg movements inlongicornis, and a dramatic increase in numbers of head nods ingiraulti. Results show that closely related species can often be distinguished based on courtship differences, although many of these differences may not contribute to a reproductive barrier.