Is it a bat or a male? A female moth (Syntomeida epilais, Lepidoptera: Erebidae: Arctiinae) adapts its acoustic signals for defense or courtship.

Abstract

Courtship behavior in the polka-dot wasp moth Syntomieda epilais is the most elaborate acoustic communication system known in the Erebidae. Both males and females must emit their acoustic signals for successful mating under natural conditions in the presence of insectivorous echolocating bats. I stimulated ninety-two females S. epilais during their courtship period (between 2:30 and 6:30 am) with playback of conspecific male and female signals and of the Mexican free-tailed bat (Tadarida brasiliensis) attack sequence. I recorded the acoustic responses of the tested females. On the third night after eclosion, at the initiation of courtship behavior, females discriminate among these three types of acoustic trains, responding preferentially to conspecific male signals. In contrast, during the first two nights after eclosion, they respond strongly to the bat attack sequence but not to conspecific male signals. I also demonstrate that after mating (six nights after eclosion) female moths stop responding to conspecific male signals, while continuing to respond to the bat attack pulse-train. These, as well as other novel observations suggest that these female moths can modulate their acoustic signals according to the stimulating conditions for defense against bats or courtship, by varying their response thresholds and latencies.