Cecropia

De Oliveira et al. (2015) - The plants of the genus Cecropia (Löefling 1758) are fast growing pioneer trees that are exclusively Neotropical (Schupp 1986; Longino 1991a; Berg & Rosselli 2005). Sixty-one species of the genus are known, but in Brazil are registered about 20 species, with higher concentration in the northeastern region (Gaglioti & Romaniuc 2012). Around 80% of Cecropia species are myrmecophylous (Davidson 2005), housing their ants, generally mutualistic, in their hollow and segmented stem and providing them with food resources, such as Müllerian corpuscles produced by trichilia (keel-shaped region located at the bottom of leaf petioles covered by velutinous mat of trichromes) and pearl bodies on the leaves (Schupp 1986; Longino 1991a; Delabie et al. 2003). The ants most commonly associated with Cecropia belong to the genus Azteca. These ants are very aggressive and control the Müllerian corpuscle production (Davidson & Mckey 1993; Davidson 2005). They also remove climbing lianas and other plants that compete for light with their host (Schupp 1986) and reduce the number of herbivores, such as leaf-cutting ants and chewing insects (Jolivet 1990; Vasconcelos & Casimiro 1997). Furthermore, the ants nourish the plant with nutrients supplied by the waste deposited within stem internodes (Sagers et al. 2000; Dejean et al. 2012). Thus, they positively influence the growth and survival of their host Cecropia (Schupp 1986; Vasconcelos & Casimiro 1997).

No Azteca species is strictly housed by a single host species, and each Cecropia species may be inhabited by more than one ant species (Longino 1989a, 1991a; Davidson & Mckey 1993). Ants of the genera Camponotus, Crematogaster, Pachycondyla and Pseudomyrmex have already been observed on Cecropia (Harada & Benson 1988; Davidson & Fisher 1991; Longino 1991a; Yu & Davidson 1997).

Neoponera luteola is one of the rare ponerine species involved in a mutualism with plants. It nests exclusively inside the stems of Cecropia tessmannii trees. The plant provides glycogen-rich Müllerian bodies on the petioles of young leaves, and this is the principal food of the ants. In return, workers protect the host plant from herbivores and encroaching vines. The colonies can get exceptionally populous as trees grow taller.

Species richness of ants associated with Cecropia is negatively related to latitude and altitude, and positively related to humidity at site and within the plant (Longino 1989a, 1991b) as well as to the architectural complexity of the latter (Reis et al. 2013). Some environmental factors also influence the richness of ants associated with Cecropia, such as open or closed forest areas (Longino 1989a, 1991a).

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