Abstract: Electrophysiological recordings of responses to its sex pheromone components from single olfactory receptor cells were carried ont in the male cotton bollworm, Heliothis armigera. The sensory cells of the longest trichiform sensilla responded specifically to the pheromone components tested. Only two types of receptor neuronswere found by inference of the measurements, each tuned to one of the female-pro-duced components. The majority of the neurons were tuned to the major component (Z)-ll-hexadecenal (Z-11-16:A1), which fired large spikes. Another group of neurons responded specifically to the stimulation with (Z)-9-he~adecenal (Z-9-16:A1),which fired small spikes. Electrophysiological recordings from these sensilla showedthat (Z)-11-hexadecenal is a major component, (Z)-9-hexadecenal is a minor com ponent.

Key words: Heliothis armigera——sensilla trichodea——single cell's recording, sex pheromone