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Occurrence of Atta cephalotes (L.) (Hymenoptera: Formicidae) in Alagoas, Northeastern Brazil

Ocorrência de Atta cephalotes (L.) (Hymenoptera: Formicidae) em Alagoas

Michele M. Corrêa Ana G.D. Bieber Rainer Wirth Inara R. Leal About the authors

Abstracts

Atta cephalotes (L.) presents a wide distribution in the Neotropical region. In Brazil, this species is disjunctly distributed in the Amazon region and in the states of Maranhão, Pernambuco and southern Bahia, all of which belong to Northeast Region. Here we report on a survey of Atta colonies in 42 remnants of the Atlantic rainforest in Alagoas and Pernambuco. Our results include new records of A. cephalotes in the state of Alagoas and thereby extend the known distribution area of its southern populations in Northeast Brazil. In addition, the species was strongly associated with well-conserved forest remnants, indicating that it is highly sensitive to disturbance. We suggest that, in the fragmented scenario of the northeastern Atlantic forest, A. cephalotes may be replaced by A. sexdens, which was present throughout all survey sites.

Brazilian Atlantic Forest; disjunct distribution; leaf-cutting ant; new record; species replacement; disturbance sensitive taxon


Atta cephalotes (L.) apresenta ampla distribuição na região Neotropical. No Brasil, foi registrada na região Amazônica e nos estados do Maranhão, Pernambuco e sul da Bahia, todos pertencentes à Região Nordeste. Neste trabalho é apresentado o registro de A. cephalotes em 42 remanescentes de Floresta Atlântica nordestina em Alagoas e Pernambuco. Os resultados incluem novos registros de A. cephalotes em Alagoas, ampliando a distribuição da espécie no Nordeste. Além disso, mostram que a espécie é fortemente associada a remanescentes de floresta bem conservados, indicando alta sensitividade a perturbações. É sugerido que, no cenário fragmentado da Floresta Atlântica nordestina, A. cephalotes pode estar sendo substituída por A. sexdens que esteve presente em todas as áreas amostradas.

Distribuição disjunta; Floresta Atlântica; formiga cortadeira; novo registro; substituição de espécies; taxon sensível a perturbações


SCIENTIFIC NOTE

Occurrence of Atta cephalotes (L.) (Hymenoptera: Formicidae) in Alagoas, Northeastern Brazil

Ocorrência de Atta cephalotes (L.) (Hymenoptera: Formicidae) em Alagoas

Michele M. CorrêaI; Ana G.D. BieberI Rainer WirthII; Inara R. LealI

IDepto. Botânica, Universidade Federal de Pernambuco, 50.670-901, Recife, PE, Brazil, correamm@uol.com.br, gabieber@hotmail.com, irleal@ufpe.br

IIAbteilung Allgemeine Botanik, Universität Kaiserslautern, Postfach 3049, 67653 Kaiserslautern, Germany, wirth@rhrk.uni-kl.de

ABSTRACT

Atta cephalotes (L.) presents a wide distribution in the Neotropical region. In Brazil, this species is disjunctly distributed in the Amazon region and in the states of Maranhão, Pernambuco and southern Bahia, all of which belong to Northeast Region. Here we report on a survey of Atta colonies in 42 remnants of the Atlantic rainforest in Alagoas and Pernambuco. Our results include new records of A. cephalotes in the state of Alagoas and thereby extend the known distribution area of its southern populations in Northeast Brazil. In addition, the species was strongly associated with well-conserved forest remnants, indicating that it is highly sensitive to disturbance. We suggest that, in the fragmented scenario of the northeastern Atlantic forest, A. cephalotes may be replaced by A. sexdens, which was present throughout all survey sites.

Key words: Brazilian Atlantic Forest, disjunct distribution, leaf-cutting ant, new record, species replacement, disturbance sensitive taxon

RESUMO

Atta cephalotes (L.) apresenta ampla distribuição na região Neotropical. No Brasil, foi registrada na região Amazônica e nos estados do Maranhão, Pernambuco e sul da Bahia, todos pertencentes à Região Nordeste. Neste trabalho é apresentado o registro de A. cephalotes em 42 remanescentes de Floresta Atlântica nordestina em Alagoas e Pernambuco. Os resultados incluem novos registros de A. cephalotes em Alagoas, ampliando a distribuição da espécie no Nordeste. Além disso, mostram que a espécie é fortemente associada a remanescentes de floresta bem conservados, indicando alta sensitividade a perturbações. É sugerido que, no cenário fragmentado da Floresta Atlântica nordestina, A. cephalotes pode estar sendo substituída por A. sexdens que esteve presente em todas as áreas amostradas.

Palavras-chave: Distribuição disjunta, Floresta Atlântica, formiga cortadeira, novo registro, substituição de espécies, taxon sensível a perturbações

The genus Atta, together with the genus Acromyrmex, represents the true leaf-cutting ants, an ecological and taxonomic group exclusively restricted to the Neotropics. Atta ants are one of the major herbivores of tropical and subtropical America, cutting per year up to 13% of the standing leaf crop in a colony's territory (Wirth et al. 2003). Moreover, they are considered the principal pest of agro- ecosystems and reforested areas (Mariconi 1970, Anjos et al. 1993). Because of the damage they cause to agriculture and the conspicuousness of their nests, they certainly belong to the most studied insect species of the Neotropics. Yet, despite the wealth of knowledge available on leaf-cutting ants, there is still a lack of basic information, such as on the geographic distribution of some species (Teixeira et al. 2004). The species Atta cephalotes (L.) is known to have a wide and continuous distribution from Mexico to Bolivia (Kempf 1972). Nevertheless, in Brazil, existent data suggest a disjunct nature of its populations. According to Mariconi (1970) and Kempf (1972), this species occurs in the entire Amazon region and also in the states of Maranhão, Pernambuco and southern Bahia, all of which belong to Northeast Brazil. In this paper, we report the occurrence of A. cephalotes in Alagoas, one of the two small states located between Bahia and Pernambuco.

Between 1999 and 2004, we surveyed a total of 42 remnants of Atlantic rainforest in Alagoas and Pernambuco for the presence of Atta colonies. The vegetation of these areas belongs to the Atlantic forest domain, ranging from lowland rain forest (< 100 m) to lower montane rain forest (100 – 600 m) (Veloso et al. 1991). Mean rainfall at all study sites ranges from 1240 mm to 2460 mm year -1, with wet- and dry-season usually from April - October, and from November - March, respectively (Coutinho et al. 1998, Pimentel & Tabarelli 2004, Bieber et al. 2005). We collected major workers of Atta spp., which were identified following the keys provided by Mariconi (1970) and Fowler et al. (1993). Identification was subsequently confirmed by two specialists. Specimens were deposited in the collections of Laboratório de Invertebrados Terrestres da UFPE, Museu Nacional (Rio de Janeiro, RJ) and Centro de Pesquisas do Cacau (CEPLAC, Ilhéus, BA).

We recorded two Atta species, A. sexdens and A. cephalotes, that differed considerably in frequency of occurrence. A. sexdens was consistently present in all of the 42 forest remnants surveyed, whereas A. cephalotes occurred in only seven of these remnants - three in Alagoas and four in Pernambuco (Table 1). In Alagoas, we found A. cephalotes in the 3500-ha fragment of Coimbra (Usina Serra Grande), one of the largest remnants of Atlantic forest of the Pernambuco Center of Endemism, and in two smaller remnants called Aquidabam 1 and Aquidabam 2 in the close vicinity of Coimbra (ca. 300 m). In Pernambuco, we recorded A. cephalotes in four neighboring remnants (less than 50 m distance) of the Reserva Particular do Patrimônio Natural (R.P.P.N.) Frei Caneca – i.e., Quengo, Fervedouro, Ageró, and Espelho (see Table 1). All of these remnants where A. cephalotes was found, except Aquidabam 2, present well-conserved forests with the four strata characteristic of mature Atlantic forest (Pimentel & Tabarelli 2004, Bieber et al. 2005) and have previously been suggested as priority areas for Atlantic forest conservation (MMA 2002).

Our record brings to discussion three issues. Firstly, it reveals a serious lack of myrmecological studies in Alagoas, resulting in the fact that even after 500 years of colonization one of the most conspicuous ant species has been overlooked by scientists.

Secondly, it represents basic distributional data and thus contributes to the understanding of biogeographic patterns in leaf-cutting ants. In the case of A. cephalotes our records in Alagoas extend the known distribution area of the southern populations of this species (cf. Mariconi 1970, Kempf 1972) and may serve as a relevant basis for further studies on the disjunct nature of its occurrence.

The third and most obvious point emerging from the present report refers to the ecological distribution and the conservation status of A. cephalotes. Our survey of variable-sized forest remnants in Alagoas and Pernambuco clearly revealed a strong association of A. cephalotes with well-conserved forest patches (or close proximity to such forests, as in the case of Aquidabam 2). We therefore suggest that in the northeastern Atlantic forest A. cephalotes is restricted to a few suitable patches of forests that experienced less anthropogenic influence. This is in line with published knowledge describing A. cephalotes as a 'woodland species' commonly found in mature or old-growth forests (Rockwood 1973, Jaffe & Vilela 1989). Given the fact that Northeast Brazil is characterized by high levels of land-use and forest fragmentation (Ranta et al. 1998) dating back to the 16th century, it is reasonable to assume that A. cephalotes populations have been subject to a drastic decline in the humid forests of this region.

In contrast, A. sexdens occurs in a wide range of habitats from primary forests to plantations and has been repeatedly suggested to benefit from the dramatic increase of human-induced disturbances (Vasconcelos 1990, Fowler 1995, Vasconcelos & Cherrett 1995, Fowler et al. 1996). The differing disturbance sensitivity between the two species may be due to a more generalist foraging behavior of A. sexdens, which allows it to adapt to a broader range of environmental conditions than the more specialized A. cephalotes (Vasconcelos 1990). As a consequence of the above, we propose that A. cephalotes is being replaced by A. sexdens in the fragmented scenario of the northeastern Atlantic forest. The lack of A. cephalotes in disturbed fragments must result from intrinsic factors that limit its capacity to colonize and survive in these habitats. A similar pattern was observed in the restinga vegetation, where Atta robusta Borgmeier is being replaced by Atta sexdens rubropilosa (Forel) (Fowler 1995, Fowler et al. 1996). But generally such environmentally induced replacement of native species by other native species has rarely been documented in ants (Fowler et al. 1994).

Our results provide evidence that A. cephalotes represents a fragmentation-sensitive species of leaf-cutting ants, the disjunct southern populations of which may be prone to local extinction because of the erosion of suitable forest habitats in Northeast Brazil.

Acknowledgments

The study was supported by German Science Foundation (DFG, project WI 1959/1-1), Fundação Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, project 007/01) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, project 540322/01-6 and 2430.00/02). Conservation International do Brasil, Centro de Estudos Ambientais do Nordeste and Usina Serra Grande provided infrastructure during the field work. We are grateful to Antônio J. Mayhé-Nunes and Jacques H. C. Delabie who confirmed the specimens' identifications of A.cephalotes, and Alexandre Grilo and Marcondes Oliveira who provided data about remnants. M.M.C. and A.G.D.B. are post-graduate students supported by CAPES grants.

Literature Cited

Received 15/XII/04. Accepted 21/III/05.

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Publication Dates

  • Publication in this collection
    26 Sept 2005
  • Date of issue
    Aug 2005

History

  • Received
    15 Dec 2004
  • Accepted
    21 Mar 2005
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