Cardiac responses to sensory stimulation in the adult tobacco budworm moth, Heliothis virescens

Electrocardiogram recordings were performed on intact Heliothis virescens moths using Ag-AgCl electrodes positioned on the body cuticular surface. Regular heart activity and its changes in response to mechanical and olfactory stimulations were analysed. Moths were also tested in their anemotactic orientation in response to olfactory stimulation. Results show that regular cardiac activity in Heliothis is cyclical and consists of the alternation of a high and a low spike-frequency period. This activity pattern is strongly influenced by sensory stimulation. Both mechanical stimulations at various intensities and olfactory stimulations with sex pheromone and 1-hexanol evoked tachycardiac effects when applied during low spike-frequency cardiac activity. In contrast, they did not affect high spike-frequency cardiac activity. It is concluded that the cardiac response in Heliothis is an effective indicator of sensory reception. It would therefore appear to represent a valid tool for testing insect reactivity.