Sexual singing in a nonchrysoperlan green lacewing, Chrysopiella minora Banks (Neuroptera: Chrysopidae)

Abstract

The courtship song of the western North American green lacewing Chrysopiella minora is described. Like the songs of better known members of the genus Chrysoperla, that of C. minora is a tremulation signal, produced by rapid vertical oscillation (jerking) of the abdomen. Both sexes produce identical shortest repeated units and must duet with one another before mating. Each shortest repeated unit is a volley of abdominal vibration about 0.25 s long, repeated twice per s. Mean abdominal vibration frequency at 27 °C is 113 Hz at the start of each volley, but drops during the course of the volley to 75 Hz. During a duet, individuals reciprocally and precisely exchange single volleys for many seconds before copulating; there is little overlap of the volleys of the partners. Temperature affects the call: linear regression equations describing temperature relationships are calculated for the important features of the song. Obligatory sexual singing by abdominal tremulation has been seen previously only in Chrysoperla, and its presence in Chrysopiella suggests independent origin in a distinct lacewing lineage. Superficial resemblance between the calls of Chrysoperla plorabunda and Chrysopiella minora is due to convergence, which can be tolerated without danger of hybridization in such distantly related species.