Receptor neuron responses to potential sex pheromone components in the caddisfly Rhyacophila nubila (Trichoptera: Rhyacophilidae)

Olfactory single sensillum responses of male and female caddisflies Rhyacophila nubila (Trichoptera: Rhyacophilidae) were examined with the tungsten penetration technique to investigate the presence of receptor neurons tuned to potential sex pheromone components. The compounds tested in the experiment were heptan-2-one, nonan-2-one, (R)-heptan-2-ol, and (R)-nonan-2-ol, which have all been found to be present in female abdominal glands, plus the two antipodes (S)-heptan-2-ol and (S)-nonan-2-ol. Four types of receptor neurons were found in equal proportions in males and females. One type responded primarily to heptan-2-one. A second type responded primarily to (R)-heptan-2-ol and a third type primarily to its enantiomer (S)-heptan-2-ol. The fourth type of receptor neuron responded to nonan-2-one, (R)-nonan-2-one, and (S)-nonan-2-ol, with a bias to nonan-2-one. The receptor neurons responding to the tested compounds made up a great majority of the contacted neurons in both males and females.