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Made available in DSpace on 2018-11-26T17:21:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-01-01 This study investigated the stimuli that trigger digging behavior inAcromyrmex subterraneus during nest building. The hypothesis was that the presence of the fungus garden and/or brood triggers the excavation of tunnels and chambers. For the experiment, the excavation rate of individually marked workers kept in plastic cylinders filled with soil was recorded. Four treatments were applied: (1) 30 medium-sized workers, 5 g fungus garden and 30 brood items (larvae and pupae); (2) 30 medium-sized workers and 5g fungus garden; (3) 30 medium-sized workers and 30 brood items; (4) 30 medium-sized workers without fungus and brood. After 24 h, morphological parameters of nest structure (length and width of the chambers and tunnels in cm) and the volume of excavated soil were recorded. In contrast to the expected findings, no change in morphological structure, rate of excavation by workers, or volume of excavated soil was observed between treatments, except for tunnel width, which was greater, when no brood or fungus garden was present. Thus, the results do not support the hypothesis that the fungus garden and/or brood are local stimuli for nest excavation or that they mold the internal architecture of the nest. Although this hypothesis was confirmed for Acromyrmex lundii and Atta sexdens rubropilosa, the same does not apply to A. subterraneus. The digging behavior of workers is probably the result of adaptation during nest building in different habitats. (C) 2016 Sociedade Brasileira de Entomologia. Published by Elsevier Editora Ltda. Univ Fed Juiz de Fora, Inst Ciencias Biol, Programa Posgrad Comportamento & Biol Anim, Juiz De Fora, MG, Brazil Univ Estadual Paulista, Fac Ciencias Agron, Dept Prod Vegetal, Botucatu, SP, Brazil Univ Fed Juiz de Fora, Inst Ciencias Biol, Programa Posgrad Ecol, Juiz De Fora, MG, Brazil Univ Estadual Paulista, Fac Ciencias Agron, Dept Prod Vegetal, Botucatu, SP, Brazil

Made available in DSpace on 2018-11-26T16:19:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-01-11 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Foraging networks are a key element for ant colonies because they facilitate the flow of resources from the environment to the nest and they allow the sharing of information among individuals. Here we report the results of an 8-month survey, extending from November 2009 to June 2010, of the foraging networks of four mature colonies of Atta bisphaerica, a species of grass-cutting ant which is considered as a pest in Brazil. We found that the distribution of foraging effort was strongly influenced by the landscape features around the nests, in particular by the permanently wet parts of the pasture in which the nests were located. The foraging networks consisted of underground tunnels which opened on average at 21.5m from the nests and of above-ground physical trails that reached on average 4.70m in length. The use of the foraging networks was highly dynamic, with few sections of the networks used for long periods of time. Three different phases, which could be linked to the seasonal change in the local rainfall regime, could be identified in the construction and use of the foraging networks. The first phase corresponded to the beginning of the rainy season and was characterized by a low foraging activity, as well as a low excavation and physical trail construction effort. The second phase, which began in February and extended up to the end of the humid season at the end of March, was characterized by an intense excavation and trail construction effort, resulting in an expansion of the foraging networks. Finally, in the third phase, which corresponded to the beginning of the dry season, the excavation and trail construction effort leveled off or decreased while foraging activity kept increasing. Our hypothesis is that ants could benefit from the underground tunnels and physical trails built during the humid season to maintain their foraging activity at a high level. Univ Fed Juiz de Fora, Programa Pos Grad Ciencias Biol Comportamento & B, Juiz De Fora, MG, Brazil Univ Fed Juiz de Fora, Programa Pos Grad Ecol, Juiz De Fora, MG, Brazil Univ Estadual Paulista, Dept Prod Vegetal, Fac Ciencias Agron, Botucatu, SP, Brazil Univ Fed Toulouse Midipyrenees, Univ Toulouse 3, Ctr Rech Cognit Anim, Toulouse 9, France CNRS, Ctr Rech Cognit Anim, UMR 5169, Toulouse 9, France Univ Estadual Paulista, Dept Prod Vegetal, Fac Ciencias Agron, Botucatu, SP, Brazil CAPES: 633/09