Role of the Corpora Cardiaca in the Behavior of Saturniid Moths. I. Release of Sex Pheromone

In virgin female silkmoths the protrusion of the genitalia or "calling" behavior signals sex pheromone release. The wild Polyphemus and Cecropia silkmoths "call" in response to specific environmental cues which are chemical and photoperiodic respectively. The semi-domesticated Pernyi silkmoth is exceptional in that it shows no overt "calling" behavior and pheromone is apparently released continuously.2. By appropriate experiments it was possible to show that the corpora cardiaca but not the corpora allata are prerequisite for the "calling" behavior. Thus, when the corpora allata are removed from female pupae, the behavior of the resulting moths is normal. By contrast, removal of the corpora allata-corpora cardiaca complex greatly reduces the number which "call."3. In order to perform their function in the "calling" behavior the corpora cardiaca must have intact connections with the brain. Reimplantation of three pairs of corpora allata-corpora cardiaca complexes into animals lacking their own complexes fails to restore the ability to "call." "Calling" is also blocked when the nervous connections between the corpora cardiaca and the brain are severed.4. Evidently, in response to the environmental signals the brain stimulates the release of a hormone from the intrinsic cells of the corpora cardiaca. This hormone then acts on the abdominal nervous system to provoke the protrusion of the female genitalia and the accompanying release of pheromone.