Pheromone-degrading enzymes (PDEs) are supposed to be involved
in the signal inactivation step within the olfactory sensilla of
insects by quickly degrading pheromone molecules. Because esters
are widespread insect pheromone components, PDEs belonging to
the carboxylesterase (CCE) family have been the most studied.
However, only two CCEs were both identified at the molecular
level and functionally characterized as PDEs until recently. In
the pest moth Spodoptera littoralis, we have identified an
unsuspected diversity of antennal CCEs, with a total number of
30 genes. Two CCEs, enriched in antennae and belonging to
distinct clades, were shown to present different substrate
specificities toward pheromone and plant compounds. A same CCE
was also shown to efficiently degrade both pheromone and plant
components. Our results suggest that the structural evolution of
antennal CCEs reflects their functional diversity and that a
complex set of CCE-mediated reactions take place is the
olfactory organs of moths. lepidopt