Koptur, Suzanne , Rico-Gray, Victor , Diaz-Castelazo, Cecilia , Palacios-Rios, Monica .
Nectar secretion on fern fronds is associated with lower levels of herbivore damage: field experiments with Pleopeltis crassinervata, a widespread epiphyte of Mexican cloud forest remnants.
Though it is not from the section of the genus Polypodium known to have some species bearing nectaries, Pleopeltis crassinervata frequently has sooty mold at the base of its fronds. This mold indicates nectar secretion, and suggested that this species may, like other epiphytic Polypodium species, benefit from ant protection supported by nectar secretion on its developing fronds. Previous experiments used sticky resin to exclude ants, but the fronds of this species are often lying flat against the tree trunks upon which they grow; we used nylon polish to cover the nectaries instead. We chose twenty-two pairs of fronds (each pair on separate plants), matched for size and developmental stage; on one of each pair we covered the nectaries with polish (experimental treatment), on the other we put polish on another part of the frond (control). Developing fronds on experimental plants (with nectaries covered) suffered greater damage than did fronds on control plants with nectaries functioning normally, suggesting nectaries attract visitors that protect the fronds against herbivores. We conducted the same experiment on a fern that does not have nectaries (Polypodium furfuraceum), and found no difference between experimental and control fronds. We found seven species of ants visiting the nectaries of Pleopeltis crassinervata, and assessed their protective abilities with caterpillar placement experiments; there was a wide range of response. Variation in ant behavior towards herbivores may explain why some individual plants showed no evident benefit from protection in this facultative association. Nectaries attracting protective agents may help Pleopeltis crassinervata, the most widespread epiphytic species, persist despite habitat disturbance, surviving on shade trees in coffee plantations in former cloud forest areas of Veracruz.
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1 - Instituto de Ecologia, A.C., Herbarium, Apto. 63, Xalapa, Veracruz, 91000, Mexico
2 - Universidad Veracruzana - Xalapa, Instituto de Neuroetología, Calle Dr. Luis Castelazo s/n, Col. Industrias Animas, Xalapa, Veracruz, 91190, Mexico
3 - Instituto De Ecologia, A.C., Apto. 63, Xalapa, Veracruz, 91000, Mexico
Presentation Type: Oral Paper:Papers for Sections
Location: Portland Room/Chase Park Plaza
Date: Tuesday, July 12th, 2011
Time: 3:00 PM