PARENT SESSION
Thursday, August 10, 8:00-11:30 am
COS 81 - Plant-herbivore interactions I
Plantation Room, Cook Convention Center
Presiders: L Altfeld

Agave palmerii facilitates mutualistic hawkmoth-plant interactions in the southwestern US.

Alarcon, Ruben^*,1, Bronstein, Judith¹, Davidowitz, Goggy¹, ¹ University of Arizona, Tucson, AZ

ABSTRACT- Hawkmoths (Sphingidae, Lepidoptera) are nocturnal pollinators that typically visit fragrant, showy flowers with concealed nectar. In the arid grasslands and foothills of southern Arizona, the emergence of adult moths and the flowering of hawkmoth plants are largely tied to the onset of summer rains. When the flowering phenologies of these plants do not encompass the entire flight period of the fauna, adult moths must find alternative nectar sources. Analysis of pollen removed from the proboscises of >500 individual hawkmoths attracted to blacklights at the Santa Rita Experimental Range (Arizona) in 2004 and 2005 suggest that 8 of 11 hawkmoth species heavily visit Agave palmerii (Agavaceae), a species morphologically adapted to bat pollination with copious volumes of nectar per flower. Pollen-load data indicate that when Datura wrightii (Solanaceae) is at its peak bloom, Manduca hawkmoths temporarily switch from Agave to Datura, which they effectively pollinate. These results suggest that Agave populations might be facilitating the Datura / Manduca and other mutualistic plant-pollinator interactions by supporting hawkmoths when alternative resources are scarce.

Key words: hawkmoth-plant interactions, Datura / Manduca mutualism, Agave palmerii