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Abstract

Female hawkmoths, Manduca sexta, use olfactory cues to locate nectar sources and oviposition
sites. We investigated if the behavioral significance
of odorants is represented already in the antennal
lobe, the first olfactory neuropil of the insect0s
brain. Using in vivo calcium imaging, we first established
a functional map of the dorsal surface of the
antennal lobe by stimulating the moths with 80
ecologically relevant and chemically diverse monomolecular
odorants. We were able to address 23 olfactory
glomeruli, functional subunits of the antennal
lobe, in each individual female. Next, we studied the
relevance of the same odorants with two-choice experiments
(odorant versus solvent) in a wind tunnel.
Depending on odorant identity, naive moths made
attempts to feed or to oviposit at the scented targets.
A correlation of wind tunnel results with glomerular
activation patterns revealed that feeding and oviposition
behaviors are encoded in the moth’s antennal lobe by the activation of distinct groups of glomeruli.