Adaptation was studied in single olfactory receptor cells of male moths of Bombyx mori and Antheraea polyphemus. Receptor potential and nerve impulse generators have different and very likely, spatially separate adaptation mechanisms possibly located in the outer dendritic segment and the cell soma, respectively. Restricted portions of the receptor cell dendrite can be locally adapted. The impulse generator may exhibit at least two distinct adaptation processes with different kinetics, as deduced from a consideration of the phasic-tonic response and the different adaptation properties of each of these phases. The response characteristics of cells in the same sensillum are different. The "faster" responding cell types resolve odor pulses with frequencies up to 10 per second--a performance that is probably needed for orientation during flight toward a small odor source.

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Inhibition of the behavioral responses of maleEpiphyas postvittana moths by theZ isorner of the major component of the sex pheromone,E11-14: OAc, was studied in a wind tunnel. Inhibition was detectable at a Z isomer concentration of 10% that of the major component and was greatest when it was added to the same source as the pheromone. Inhibition declined rapidly as the inhibitor was moved across-wind away from the pheromone source but was largely maintained when the sources were separated upwind or downwind. The results showed that the insects possess a high degree of temporal resolution for odor plumes of different composition.

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