Meeting Abstract
The male hawkmoth Manduca sexta is known to have antennal receptive fields of female sex pheromone-responsive projection neurons in the antennal lobe. There are about 80 antennal segments and the distribution of the pheromone-sensitive trichoid sensilla is greater on the middle segments of the antenna, compared to the tip and the base. In flight posture, the tips of the two antennae are ca. 2 cm apart. Using both bilateral sampling and the different receptive fields on the antennae, the moths could extract odor detailed information on spatial distribution of odor instantaneously. Importantly, the cross section of the odor plume gets narrower near the source. Taken together, it could be suggested that the M. sexta could use bilateral sampling strategy to locate the odor source more efficiently. In order to test this hypothesis, we studied the odor plume tracking behavior of M. sexta with varying length of antennal segments. For this study we used moths with 10, 20, 40 and 80 (fully intact) bilateral antennal segments. Once surgically removed the cut antennal segments were glued back onto the intact antennal segments, to restore the input from the Johnston’s organ at the base of the antenna. Moths with intact antennae were successful in finding the odor source (97%, n = 37). Moths with 40 antennal segments, i.e., 50% intact antenna, performed well as intact controls (91%, n = 24) in locating the odor source. Fewer of the moths with 20 & 10 antennal segments (n = 15 & 11) (i.e., less than 50% of their functioning olfactory sensillae) succeeded in locating the odor source and exhibited great difficulty maintaining contact with and tracking the odor plume. The reduction in spatial resolution could have effected their inability to track and locate the odor source.
