Bimodal pollination system of the bromeliad Aechmea nudicaulis involving hummingbirds and bees

Abstract

In order to compare the effectiveness of birds and insects as pollinators, we studied the floral biology of the bromeliad Aechmea nudicaulis (L.) Grisebach in the biome of the Atlantic rain forest, southern Brazil. On Santa Catarina Island, flowering extends from mid-September to the end of December, with diurnal anthesis. The reproductive system is obligatory xenogamy, thus pollinator-dependent. Flowers secrete 31.84 μl of nectar per day, with a mean sugar concentration of 23.2%. Highest nectar volume and sugar concentration occur at the beginning of anthesis. Most floral traits are characteristic for ornithophily, and nectar production appears to be adapted to the energy demand of hummingbirds. Continued secretion of the sucrose-dominated nectar attracts and binds visitors to inflorescences, strengthening trapline foraging behaviour. Experiments assessing seed set after single flower visits were performed with the most frequent visitors, revealing the hummingbird Thalurania glaucopis as the most effective pollen vector. In addition, bees are also functional pollinators, as substantiated by their high visitation frequency. We conclude that this pollination system is bimodal. Thus, there is redundancy in the pollination service provided by birds and bees, granting a high probability of successful reproduction in Ae. nudicaulis.

Floral visitors and potential pollinators of a rupicolous bromeliad (Pitcairnioideae) in the Brazilian semiarid

“…The largest impact of the bee's pillage behavior must be in pollen collection because they are generally considered efficient when removing pollen from the anthers. Bees are the most important pollinating insects for angiosperms and form the group with greatest diversity involved in the pollination of many plant species (Zanette et al, 2005), also playing an important role in the pollination of bromeliads (Benzing, 2000;Schmid et al, 2011).…”

“…Bromeliads are an important component in maintaining biological diversity (Siqueira Filho and Machado, 2001;Rios et al, 2010;Santana and Machado, 2010), since they provide shelter, serve as a substrate for foraging and even as a breeding site for many organisms (Ramalho et al, 2004;Romero and Vasconcellos-Neto, 2005;Andrade et al, 2009). They are also a food resource for floral visitors (Siqueira Filho and Machado, 2001;Kaehler et al, 2005;Rios et al, 2010).…”

“…Despite the great diversity of floral visitors reported for Bromeliaceae, mainly in the genera Aechmea, Tillandsia, Vriesea and Puya (Sazima et al, 1989;Siqueira Filho and Machado, 2001;Nara and Weber, 2002;Mendonça and Dos Anjos, 2003;Rios et al, 2010), little is known about the floral visitors of the genus Encholirium. An exception is the study performed on Encholirium spectabile Mart.…”

An overview on pollination of the Neotropical Poales

“…Further examples include pollination by hummingbirds (Canela 2006) and bats (Sazima et al 1995) in Vriesea longicaulis Mez, and flowers of Aechmea nudicaulis (L.) Griseb. that were mainly pollinated by hummingbirds (Sazima et al 1996;Buzato et al 2000;Araujo et al 2004;Canela 2006;Machado & Semir 2006;Piacentini & Varassin 2007), but were also visited by bees (Schmid et al 2011). Indeed hummingbirds and bees was the most frequent combination (58.3%) of mixed pollination systems in Bromeliaceae, recorded in Aechmea nudicaulis (Schmid et al (Buzato et al 2000;Guerra et al 2010), Pitcairnia staminea Lodd.…”

“…Moreover, possible reversals to wind-or animal-pollination, changes in the type of pollinators in zoophilous groups (e.g. from hummingbirds to bee or bats, Sazima et al 1995;Canela 2006;Schmid et al 2011) and the arising of pollination by wind and animals (ambophily) (Costa & Machado 2012) were also observed.…”