Am Angioy

An endocrine control mechanism for chemosensillar activity in the blowfly

Juvenile hormone (JH) administration increases the sensitivity of labellar chemosensilla inPhormia. It is suggested that this hormone plays a role in controlling both chemosensillar sensitivity and ovarian cycles.

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

Abstract 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.

Importance of the viscous substance at the tip of the labellar taste hairs ofPhormia regina M. on the salt-sugar interaction

The role of the mucopolysaccharide layer at the tip of labellar taste hairs ofPhormia regina M. on the inhibitory mechanism of sugar ont he stimulating effect of salt and vice versa has been investigated.

Electrical resistance and spike activity in tarsal chemosensilla of Phormia regina (Meig.).

The relationship between hair electrical resistance and responsiveness to stimulation has been investigated in the tarsal chemosensilla ofPhormia regina. Results showed that the lower the hair electrical resistance, the higher is the spike-firing frequency.