Ground-foraging ants (Hymenoptera: Formicidae) and rainfall effect on pitfall trapping in a deciduous thorn woodland (Caatinga), Northeastern Brazil

Abstract

The semi-arid Caatinga is the fourth largest biome of Brazil, which biota still remains one of the most poorly known, especially with regard to invertebrate groups. In this study, a ground-foraging ant assemblage was surveyed during one year and the effect of rainfall on pitfall trapping was assessed. The study was performed in an area located in the municipality of Pentecoste (3º48' S-39º20' W), in the State of Ceará. A 200m transect with 20 equidistant sampling points was established. Transect sampling was performed once a month during 12 months, over the period August 2008-August 2009. At each sampling point, a pitfall trap partially filled with a mixture of ethanol and monoethylene glycol was placed at the beginning of each month and remained in the field for seven days. 39 species belonging to six subfamilies and 19 genera, plus two unidentified species, were collected, with Pheidole (10 spp.) and Camponotus (8 spp.) being the taxa with the most species. 23 species were frequent, being found in more than 50% of the 12 transect samplings. Five species had an intermediate frequency (25 to 50%), while 13 were relatively infrequent (less than 25%). Most of the species (22) showed low occurrence, being found in less than 10% of the 240 samples (20 samples each month, during 12 months). Only five species were collected in more than 50% of the samples, those species being also responsible for most of the total abundance (number of captured individuals of all species) observed each month. The speciesaccumulation curves (observed and estimated) indicated that sampling sufficiency was attained, and that about 92% of the estimated ground-foraging ant fauna had been collected. 40 and 29 species were collected in the dry and rainy season, respectively, with monthly species richness ranging from 13 to 28. The total ant abundance showed a drastic decrease during the rainy season, and a negative linear correlation was found between rainfall and total ant abundance (R 2 =0.68). A similar negative linear correlation was found for species occurrences against rainfall (R 2 =0.71), and for mean number of species per pitfall trap against rainfall (R 2 =0.71). However, some species showed equal abundance, occurrence and mean number of individuals per pitfall trap in both seasons, while others showed a much higher abundance and occurrence during the rainy season. Pitfall trapping as a method to sample ground-foraging ant assemblage of the Caatinga biome and potential factors responsible for lower pitfall trap performance during rainy season are discussed.

Land use and terrestrial arthropods at the Colombian Pacific coast

“…The activity of the terrestrial arthropods as documented by the captures in the pitfall traps did not vary with the amount of rainfall. This is in stark contrast to observations of Nunes et al (2011) and Delsinne et al (2008), where ant numbers in semi-arid areas (Brazilian Caatinga and Paraguayan Chaco, respectively) were drastically reduced by rainfall. However, this could be expected, as our study area is part of the Chocó biogeographic region with rainfall records of up to 12,000 mm.…”

“…In the same study, Ectatomma quadridens (F. 1793) is mentioned as a predator of S. valida. In Colombia, E. ruidum has also been associated with predation of spittle bugs in pastures, insect pests of citrus (Abadia Lozano et al 2013) and various pests of coffee (Mera Velasco et al 2010). Velázquez et al (2006) identified E. ruidum among the important predators of the agave weevil, Scyphophorus acupunctatus Gyllenhal, 1838 (Coleoptera: Curculionidae) in Venezuela with presence in almost all the sampled areas.…”

poral dynamic of foraging of epigeic ants in an urban forest fragment

“…The other species that were found in the four samples had highest abundance in the months of rainy season (January and October). This results may be related to the foraging strategy of each species (PORTER;TSCHINKEL, 1987), to the physical barrier imposed by rain, to the efficiency of the pitfall trap during the rainy months, and to the variation of available resources (NUNES et al, 2011). According to Dos Santos et al, (2012), in the Cerrado biome, during the months with lowest precipitation, the availability and quality of food fall sharply, influencing populations directly, including some ant species (see COGNI;OLIVEIRA, 2004;YAMAMOTO;DEL-CLARO 2008).…”

When the company does not matter: High‐quality ant seed‐disperser does not drive the spatial distribution of large‐seeded myrmecochorous plants

“…ribifolia ), we assessed the online SpeciesLink database (available at http://www.splink.org.br/). To access the occurrence points of D. quadriceps , we searched for papers in the Scopus and Web of Science online database in which we could gather georeferenciated information about sites in which this species was collected (Santana‐Reis & Santos ; Vasconcellos et al ; Quinet & Tavares ; Araújo & Rodrigues ; Nunes et al ; Santos et al ,, ; Medeiros et al ; Nascimento et al ; Cologna et al ; Ulysséa & Brandão ; Lenhart ; Torres et al ; Leal et al ,b). For D. quadriceps , we have only selected occurrence points located in Caatinga vegetation because the selected plant species are strictly associated to this ecosystem (Fig.…”