Pollination ecology of Agave macroacantha (Agavaceae) in a Mexican tropical desert. II. The role of pollinators

We did a series of observational studies and manipulative experiments on th e guild of nocturnal visitors of Agave macroacantha, including (1) a descri ption of the hourly patterns of visits by moths and bats, (2) an evaluation of the relative contribution of bats and moths to flowering success, and ( 3) an evaluation of the pollination efficiency of the different bar species . Scapes exposed to moths but excluded to bats yielded similar to 50% fewer fruits than those exposed to both pollinator groups. Flowers exposed to th e bat species Leptonycteris curasoae showed similar fruiting success to tho se exposed to Choeronycteris mexicana and to those exposed to the whole noc turnal visitor guild. However, the fruits originated from flowers pollinate d by Lepronycteris curasoae yielded significantly more seed than those expo sed to Choeronycteris mexicana or to the whole pollinator guild. It is conc luded that Agave macroocantha is extremely dependent on nocturnal pollinato rs for its reproductive success and that bats are especially important for successful pollination. Some of these pollinators are migratory and have be en reported to be steadily declining. A continuing decline in the populatio ns of pollinators may impede the successful sexual reproduction of the plan t host and may put the long-term survival of this agave species under risk.