Antennal neurones specific for redundant pheromone components in normal and mutant Trichoplusia ni males

Abstract Recordings were made from the pheromone‐sensitive receptor cells within antennal hairs of normal and mutant male cabbage loopers, Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae), using a cut‐sensillum technique. From sampling 136 sensilla on normal males and 123 on mutant males, cells excited by pairs of behaviourally redundant minor pheromone components were discovered: Z9–14: Ac was found to be replaceable with 12: Ac and 11–12: Ac was found to be replaceable with Z5–12: Ac. These cells were not found during previous neurophysiological investigations, but explain most of the associations between mutually replaceable (redundant) pheromone components which had been demonstrated previously to be behaviourally redundant in wind tunnel studies. Our results indicate that the mutant gene in T.ni that affects pheromone production does not affect pheromone receptors in males. Using both AC‐ and DC‐coupled recordings from receptor cells, we found that a single minor component could apparently hyperpolarize one cell while depolarizing another cell within the same sensillum, suggesting that noise reduction and other complex signal processing by receptor cells may contribute to odour processing in the macroglomerulus of the antennal lobe. 1992 Royal Entomological Society