Comparison of the mating behaviour of a bush cricket in the laboratory and the field: Calling activity and mating frequency of a long-winged species, Phaneroptera falcata (Ensifera: Tettigoniidae)

Abstract

Bush crickets are a model group for testing hypotheses in sexual selection, but much of the information is based on labora - tory observations on wingless or short-winged species, which may restrict their generality. Here we describe aspects of the mating be- haviour of the long-winged e uropean bush cricket Phaneroptera falcata (Poda, 1761). Both in the laboratory and the field, diel calling followed a normal, though slightly left-skewed distribution, peaking about three hours after sunset or lights-off. u nder bright green- house conditions, when the light was suddenly switched off, calling occurred only after the onset of darkness. Decreasing light intensity may trigger the start of calling activity. i n the field, calling decreased from midnight onwards, which may be related to a decrease in temperature. The sequence of events during copulation was identical in the laboratory and the field. h owever, in two of 14 copulations documented in the field, a pre-copulatory behaviour was observed that resembled the putative removal and ingestion of rival sperm. Previous suggestions that P. falcata (Poda) is monogamous are rejected on the basis of both laboratory and field results. i n the labora- tory males and females mated every 2.3 and 3.6 days, respectively. We introduce a simple way to calculate the average frequency of mating in the field, based on the observation that at any one time 3% of all the individuals are recorded mating and copulation lasts 15 min. We estimate that on average P. falcata (Poda) mates once per day. More generally, our results show it is important for evolutionary conclusions to measure behaviourial data in the field.