Interactions of pheromone with moth antennae: Adsorption,desorption and transport

Isolated antennae of the male moth Antheraea polyphemus adsorbed at least 32% of ³H-labelled pheromone molecules (E-6,Z-11 hexadecadienyl acetate) from an airstream passing the antenna. About 80% of the adsorbed molecules were caught by the long olfactory hairs (sensilla trichodea). The distal half of the hairs caught about twice as many molecules as the proximal half. About 40% of the molecules desorbed if the antennae were exposed to a clean airstream for 30 min. The adsorbed molecules were transported from the hairs towards the antennal branch. Transport due to diffusion would have a diffusion coefficient of 3 × 10^?7 cm²/s. Forty per cent of the total radioactivity per hair could be detected in receptor lymph extruded from the olfactory hairs, after an incubation time of 2 min. Dried antennae showed an increased desorption and an increased velocity of the transport along the hairs. One interpretation is that the molecules enter the receptor lymph of the intact antennae and diffuse more slowly than those on the cuticular surface. Fractional elution of fresh antennae revealed a diminishing elutability of pheromone from antennae in pentane (DEP-effect) and almost constant elutability in more polar solvents (chloroform-methanol toluene). The DEP-effect could be reversibly abolished by dehydration of the antennae. It could be shown that the DEP-effect occurs mainly on the antennal branch rather than on the hairs. Residual (uneluted) radioactivity builds up mainly on the branch.