Hindawi Publishing Corporation Psyche Volume 2012, Article ID 172739, 6 pages doi:10.1155/2012/172739 Research Article Tree-Dwelling Ants: Contrasting Two Brazilian Cerrado Plant Species without Extrafloral Nectaries Jonas Maravalhas,1 JacquesH.C.Delabie,2 Rafael G. Macedo,1 and Helena C. Morais1 1 Departamento de Ecologia, Instituto de Biologia, Universidade de Bras´ılia, 70910-900 Bras´ılia, DF, Brazil 2 Laboratorio´ de Mirmecologia, Convˆenio UESC/CEPLAC, Centro de Pesquisa do Cacau, CEPLAC, Cx. P. 07, 45600-000 Itabuna, BA, Brazil Correspondence should be addressed to Jonas Maravalhas, [email protected] Received 31 May 2011; Revised 28 June 2011; Accepted 30 June 2011 Academic Editor: Fernando Fernandez´ Copyright © 2012 Jonas Maravalhas et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Ants dominate vegetation stratum, exploiting resources like extrafloral nectaries (EFNs) and insect honeydew. These interactions are frequent in Brazilian cerrado and are well known, but few studies compare ant fauna and explored resources between plant species. We surveyed two cerrado plants without EFNs, Roupala montana (found on preserved environments of our study area) and Solanum lycocarpum (disturbed ones). Ants were collected and identified, and resources on each plant noted. Ant frequency and richness were higher on R. montana (67%; 35 spp) than S. lycocarpum (52%; 26), the occurrence of the common ant species varied between them, and similarity was low. Resources were explored mainly by Camponotus crassus and consisted of scale insects, aphids, and floral nectaries on R. montana and two treehopper species on S. lycocarpum. Ants have a high diversity on cerrado plants, exploring liquid and prey-based resources that vary in time and space and affect their presence on plants. 1. Introduction presented by Schoereder et al. [2] indicate that the presence of EFNs does not affect ant species richness within a given Foliage-dwelling ants are an important component in tropi- tree and there is no particular ant species composition typical ff cal environments [1–3], a ecting locally the composition of plants with EFNs. and abundance of other insect communities [4–6]and To link the richness and seasonal variation of ants to directly or indirectly driving mutualistic and trophic inter- attractive resources available on a particular plant species, actions in plant-herbivore-predator/parasite interactions [7– we compared ant assemblages on two species that do not 11]. High abundance and richness of ants on this stratum bear EFNs and are common of the cerrado region of central are due to a highly energetic liquid diet, mainly extrafloral Brazil: Roupala montana Aubl. (Proteaceae) and Solanum nectaries (EFNs) and hemipteran honeydew [12–14]. Ants lycocarpum St. Hill. (Solanaceae). In our sampling area, use a variety of resources from plants and their herbivores both plants have similar stature and structure, are consumed and these associations are facultative and vary temporally by myrmecophilous hemipterans [21, 22], and were found and spatially [1]. in different environments: R. montana occurring in native In the cerrado, a savanna-like vegetation in central cerrado vegetation, where S. lycocarpum is rarely found, Brazil, there is a high proportion of plants bearing EFNs, being common in altered areas at the borders of roads and representing up to 31% of the plant individuals surveyed agropastoral fields. The ability of S. lycocarpum to establish [15, 16] and a rich fauna of ants exploiting them [2, 17– itself in a wider range of environments supposedly leads 19]. A vast literature about direct and indirect associations to bigger ant richness, in contrast to R. montana. On the of ants and plants in this biome is available [20], but there other hand, impoverished areas, where S. lycocarpum occurs, are few studies comparing ant faunas and their resources can sustain weaker ant diversity, which can affect the ant between plant species, especially those without EFNs. Results fauna foraging on this species. We expect that differences 2 Psyche on the area of occurrence and resource availability between Table 1: Frequency of occurrence of ants and myrmecophilous these plant species may lead to important differences in the hemipterans on Roupala montana (Proteaceae) and Solanum lyco- composition of ant species. carpum (Solanaceae), in Fazenda Agua Limpa, Federal District, Brazil. Comparisons made with contingency tables. 2. Material and Methods Caracteristics Roupala Solanum χ2 P 2.1. Study Area. This study was conducted in the Fazenda Examined plants 327 431 Agua Limpa (15◦57S, 47◦54W), Federal District, Brazil. Plants with ants 218 226 15.517 0.0001 Plants with myrmecophilous This 4,500 ha farm belongs to the University of Brasilia 139 188 0.094 0.816 and includes mainly undisturbed cerrado vegetation and hemipterans Co-occurrence of ants and agro-silvo-pastoral experimental areas. The region has alti- 115 143 0.328 0.620 tudes around 1,050 m a.s.l., average annual temperature of hemipterans ◦ Plants with hemipterans 22 C, and average annual rainfall of 1,417 mm (series from 24 45 2.161 0.141 1980 to 2004, data from RECOR Meteorological Station, without ants Plants with ants without http://www.recor.org.br/), and a marked seasonality, with a 103 83 15.046 0.0001 lengthy dry season ranging from May to September and a wet hemipterans season from October to April. 2.2. Plant Species. Roupala montana is widely distributed period. Every ant observed on the plant was collected and in the Brazilian cerrado [23] and is abundant in cerrado the occurrence of myrmecophilous hemipterans registered. remnants of the Federal District. It is an evergreen shrub Roupala montana plants (n = 327) were examined between that simultaneously sheds leaves and produces new ones, April and September (dry season) of 2007 in a typical reaching up to three meters height, blooms for a long period cerrado vegetation area of 2 ha. Previous surveys in the during the year, and is pollinated by moths [24–26]. It same study area were made on this species during the wet hosts ant-tended hemipterans like scale insects (Coccoidea), season of 2006, when the focus was to collect the ants aphids (Aphidoidea), and, especially a leafhopper species, tending nymphs of Rotundicerus sp. (n = 116). Solanum Rotundicerus sp. (Cicadellidae and Idiocerinae), which forms lycocarpum plants (n = 431) were inspected between large aggregates of nymphs feeding on new leaves at the March 2007 and March 2008 along dirt roads that cross a beginning of the rainy season [21].Arichfaunaofcater- mosaic of environments, including typical and “campo sujo” pillars, including Hallonympha paucipuncta (Spitz, 1930) (a physiognomy dominated by herbaceous vegetation) native (Riodinidae) and at least 10 species of Lycaenidae, consumes cerrado areas, pastures and cultures of coffee, sorghum, and its leaves and inflorescences [27–29]. pine. The sampling area of S. lycocarpum wasmorewidely Solanum lycocarpum is an evergreen shrub with max- imum height of about two meters, being extremely com- spread than that of R. montana. mon in disturbed environments [30, 31]. New leaves and The mean similarity of ant species composition between flowers grow throughout the year, but flowers do not the two plant species was calculated by grouping the samples n = reward nectar to insects, and pollen is the floral resource of each month from April and October ( 7). The collected by bumblebees through buzz pollination behavior similarity indexes and rarefaction curves were generated [30]. Leaf surfaces are covered with simple glandular and using EstimateS [39]. The frequency tests were made using nonglandular trichomes and stellate trichomes [32]. The BioEstat 5.0 [40]. treehopper Enchenopa brasiliensis Strumpel,¨ 2007 (Mem- bracidae) is a common species feeding on apical meristems and inflorescences [22]. In the study area, two species of 3. Results Membracidae, one of Aetalionidae and an inderterminated Ants were more frequent on R. montana (67%) as compared number of species of scale insects were tended by ants on to S. lycocarpum (52%) and this difference was due to new leaves of this plant. One Cicadelidae species was very higher occurrence of ants on R. montana plants without abundant too on the same plants, but it was not associated myrmecophilous hemipterans (Table 1). Along the study with ants. Solanum lycocarpum leaves are eaten by several we collected a total of 45 ant species from 11 different microlepidoptera, especially Symmetrischema chloroneura (Meyrick, 1923) (Gelechiidae) [33], its stems are consumed genera. We recorded 35 species on R. montana and 26 on S. ± by gall-forming weevil, Collabismus clitellae Boheman, 1837 lycocarpum, with estimated richness (first order Jackknife (Curculionidae) [34] and its leaves and fruits are eaten standard deviation) of 40 (± 2.6) and 29 (± 2.3), respectively, by several species of mammals [31, 35–37]. Attini nests (Figure 1; Table 2). (Formicidae and Myrmicinae) favor the establishment of The frequency of occurrence of the most common ant seedlings and enhance nutrient in the leaves of S. lycocarpum species were different on the two plant species (Table 2) [38]. and the mean similarity (±sd) of the ant assemblages for the dry season was low (Sorensen Index = 0.419 ± 0.078), 2.3. Samples and Data Analysis. Individuals of both plant especially when the frequency of occurrence of ant species species were carefully examined always in the morning was considered (Morisita-Horn Index = 0.372 ± 0.167). Psyche 3 35 lycocarpum, but small ants, like some species belonging to the genera Brachymyrmex, Dorymyrmex, Pheidole, and 30 Solenopsis, possibly use this resource. Pseudomyrmex spp. were generally present (68%) on plants without myrme- 25 cophilous hemipterans. 20 4. Discussion 15 Ant species We found a high frequency of plants visited by ants, 10 showing the prevalence of ants foraging on cerrado plants, even during the dry season, when R.