POWER OUTPUT AND EFFICIENCY OF SOUND PRODUCTION BY CRICKETS

I estimated the sound power of male crickets calling outdoors using a microphone array to measure their sound fields. Average power output for four species, Scapteriscus borellii (N = 18), S. vicinus (N = 7), Oecanthus quadripunctatus (N = 6), and Anurogryllus arboreus (N = 6), was 6.5, 4.5, 10.2, and 58.6-mu-W, respectively. Power output for male mole crickets (Scapteriscus spp.) was variable (range 2-22-mu-W), and estimated efficiency was less than 0.1%. Efficiencies of sound production for tree crickets (Oecanthus) and short-tailed crickets (Anurogryllus) were between 1% and 3%. Power output of S. vicinus males was significantly correlated with soil moisture near the male's burrow. Larger Oecanthus males produced significantly more power than smaller males. Male Oecanthus that used leaves as baffles increased power output by a factor of 2 (3 dB). Radiation patterns of Scapteriscus sound fields were hemispherical. Those of Oecanthus and Anurogryllus were dumbbell shaped. Radiation patterns of Scapteriscus and Oecanthus are predicted by simple physical systems. The costs and benefits to male reproduction due to increased power output relate to changes in efficiency of sound production and preferences used by females, competitors, or natural enemies in locating calling males.