|Alarcon Jr, Ruben|
Submitted to: Proceedings of the National Academy of Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2008
Publication Date: 3/4/2008
Citation: Riffell, J. A., Alarcon, R., Abrell, L., Davidowitz, G., Bronstein, J. L., Hildebrand, J. G. Behavioral consequences of innate preferences and olfactory learning in hawkmoth-flower interactions. Proceedings of the National Academy of Sciences (105)9:3404-3409. 2008. Interpretive Summary: Pollinators possess the ability to visit alternative floral resources when preferred host plants are scarce. To understand the behavioral mechanisms controlling floral preference we studied the hawkmoth Manduca sexta, in the semi-arid grassland of Arizona. Here, hawkmoths forage primarily on Agave palmeri, but shift to the moth-adapted flowers, Datura wrightii, when they become abundant. Both plants emit similar concentrations of floral odor, but scent composition, nectar, and flower color are distinct. Although Agave palmeri provides 114 times the calories than D. wrightii flowers do, hawkmoths prefer D. wrightii's odor profile and readily switch to D. wrightii flowers.
Technical Abstract: Spatiotemporal variability in floral resources can have ecological and evolutionary consequences for both plants and the pollinators upon which they depend. The behavioral mechanisms that allow floral visitors to persist when a preferred floral resource is scarce, however, rarely have been considered. To understand these mechanisms better, we examined factors controlling floral preference in the hawkmoth, Manduca sexta, in the semi-arid grassland of Arizona, USA. Here, hawkmoths forage primarily on flowers of the bat-adapted agave, Agave palmeri, but shift to the moth-adapted flowers of its larval host plant, Datura wrightii, when they become abundant. Both plants emit similar concentrations of floral odor, but scent composition, nectar, and flower reflectance are distinct between the two flower species, and A. palmeri flowers provide 114 times as much chemical energy (J/cm2) as flowers of D. wrightii. Behavioral experiments with both naive and experienced moths revealed that hawkmoths learn to take nectar from agave flowers through olfactory conditioning but readily switch to D. wrightii flowers, for which they are the primary pollinator, based on an innate odor preference. Behavioral flexibility and the olfactory contrast between flowers permit the hawkmoths to persist within a dynamic environment, which at the same time to function as the major pollinator of one plant species.