Invasão de áreas de savana intra-amazônicas por Digitonthophagus gazella (Fabricius, 1787) (Insecta: Coleoptera: Scarabaeidae)

Abstract

RESUMONeste estudo, foi avaliada a invasão da comunidade de Scarabaeinae detritívoros de uma savana amazônica pela espécie africana Digitonthophagus gazella (Fabricius 1787). O estudo foi realizado nas proximidades da vila de Alter do Chão (2º 31' S e 55º 00' W), localizada a aproximadamente 36 km a sudoeste de Santarém, Pará, Brasil. Vinte e duas áreas de savanas de 3,75 ha (250 x 150 m) distribuídas em 30.000 ha foram amostradas, no período de 21 de julho a 13 de agosto de 2003, utilizando 66 armadilhas de queda com três tipos de iscas (fezes bovinas, fezes humanas e carcaças). Foram encontrados indivíduos de D. gazella em quatro das vinte e duas áreas amostradas. Procurou-se explicar a presença da espécie nas áreas de savana através de análises de regressão logística, onde as variáveis explicativas foram: ocorrência de queimada nos últimos seis anos, diversidade e abundância total de Scarabaeidae nativos presentes na área, abundância de Canthon sp.1, (espécie de Scarabaeidae mais abundante na região). Exceto pela abundância total de indivíduos de Scarabaeidae nativos, nenhuma das variáveis bióticas e abióticas tiveram efeito estatisticamente significativo na presença do D. gazella. Estes resultados podem ser explicados por: (a) algum fator ainda não analisado, relacionado à invasão da área pelo D. gazella; (b) Não houve tempo para a dispersão e estabelecimento da espécie em todas as áreas; (c) A comunidade nativa de Scarabaeinae apresenta resistência à invasão pelo D. gazella. PALAVRAS-CHAVE:Amazônia, Ecossistema tropical, Brasil, Invasão biológica. Invasion of intra-Amazonian savannas by the dung beetleDigintonthophagus gazella (Fabricius, 1787) (Insecta: Coleoptera: Scarabaeidae) ABSTRACT This work aimed to verify the invasion of the dung beetles community from intra-Amazonian savanna by the African species Digitonthophagus gazella (Fabricius 1787). The research was carried out near Alter do Chão village (2º 31' S; 55º 00' W), 36 Km Southwest of Santarém, Pará, Brazil. Twenty two areas were sampled, from 21 July to 13 August 2003, using 66 baited pitfall traps (cattle dung, human faeces and carcass bait). D. gazella individuals were found in four of twenty two sampled areas. The presence of the species in the savanna was analysed by a logistic regression, using the occurrence of burnings in the last six years, species richness and abundance of native Scarabaeinae, and abundance of Canthon sp1, (the most abundant species in the region), as explanatory variables. Except for the total abundance of native Scarabaeinae, none of the variables were statistically significant for the presence of D. gazella. Hypothetically, these results were probably due to a non-analysed factor related to the invasibility of the area by D. gazella, or lack of time for the species to disperse and establish in all the areas, or a resistance of native dung beetle community to D. gazella invasion. Nevertheless, there must be a competitive mechanism of invasion resistance bounding the abundance of native species and D. gazella invasi...

First report on dung beetles in intra-Amazonian savannahs in Roraima, Brazil

“…In addition, the species reported here were also found within highly impacted Brazilian forests, such as northeastern fragments of Atlantic forest (Salomã o & Iannuzzi 2015, Viegas et al 2014, planted Eucalyptus sp. forests and Amazonian secondary forests, savannahs and agricultural areas , Louzada et al 2010, Matavelli & Louzada 2008. The number of dung beetle species and individuals reported here was lower than in other intra-Amazonian savannahs (Louzada et al 2010, Matavelli & Louzada 2008, southern cerrado (Abot et al 2012, Almeida et al 2011, Durães et al 2005, Gries et al 2012, Vieira & Silva 2012 and native grasslands of the 'Pampa' region .…”

“…forests and Amazonian secondary forests, savannahs and agricultural areas , Louzada et al 2010, Matavelli & Louzada 2008. The number of dung beetle species and individuals reported here was lower than in other intra-Amazonian savannahs (Louzada et al 2010, Matavelli & Louzada 2008, southern cerrado (Abot et al 2012, Almeida et al 2011, Durães et al 2005, Gries et al 2012, Vieira & Silva 2012 and native grasslands of the 'Pampa' region . We believe this lower species-rich sample can be due the historical isolation of the intra-Amazonian from the cerrado savannahs in central Brazil during the Pleistocene period (Sanaiotti et al 2002), besides some natural specific habitat characteristics, such as edaphic factors, vegetation structure and fire occurrence (Barbosa & Fearnside 2005, Louzada et al 2010).…”

“…As such, we have sampled six species without any previous occurrence from intra-Amazonian savannahs, as only the dung beetle species O. appendiculatus, D. nisus, P. aff. xanthurus and C. mutabilis have been previously recorded in these environments (Génier 1996, Louzada et al 2010, Matavelli & Louzada 2008.…”

“…Although extensively sampled with dung baited pitfalls, the species have been considered as generalist (Andrade et al 2011), with records from open habitats in Colombia and Venezuela (Ferrer-Paris et al 2013). In Brazil they have been reported within pastures and grasslands (Costa et al 2009, Schiffler et al 2015, Silva et al 2014), caatinga (Lopes et al 2006, degraded restinga , northeastern Atlantic forest , Salomão & Iannuzzi 2015, intra-Amazonian savannahs (Matavelli & Louzada 2008) and Amazonian agricultural areas ).…”

“…Regarding their diversity within Brazilian opened areas, studies have recorded between 13 and 66 species from the Brazilian southeastern savannahs (known as 'cerrado') and pasturelands (Abot et al 2012, Almeida et al 2011, Durães et al 2005, Gries et al 2012, Milhomem et al 2003, Vieira & Silva 2012. Furthermore, 15 dung beetle species were reported from the intra-Amazonian savannahs near to Alter do Chão village, state of Pará, Brazil (Louzada et al 2010, Matavelli & Louzada 2008. Hence, considering the dung beetles' ecological importance in many ecosystem processes (Nichols et al 2008) and the poor knowledge about their fauna from the largest intra-Amazonian savannah area in Brazil, here we aimed to present the dung beetle species that were sampled within three lavrado savannahs of Roraima state, Brazil.…”