Navegando por Autor "Souza, Og Francisco Fonseca de"
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Item Convergence in the variation of local and regional galling species richness.(2005) Carneiro, Marco Antonio Alves; Fernandes, Geraldo Wilson Afonso; Souza, Og Francisco Fonseca deForam investigados os determinantes locais e regionais da riqueza de insetos indutores de galhas sobre o arbusto dióico Baccharis concinna Barroso (Asteraceae) na porção sudeste da Cadeia do Espinhaço, MG. O número total de espécies de insetos indutores de galhas e a riqueza de Cecidomyiidae (Diptera) foram influenciados pelo sexo da planta. Plantas masculinas apresentaram maior riqueza de insetos indutores de galhas do que plantas femininas, corroborando a hipótese da herbivoria mediada pelo sexo na comunidade. O número total de espécies de insetos galhadores e a riqueza de Cecidomyiídeos mostraram um pico em altitudes intermediárias. A riqueza de todas as espécies de insetos galhadores e de cecidomiideos foi fortemente influenciada pelo habitat. Plantas no habitat xérico apresentaram mais espécies de insetos galhadores do que plantas no habitat mésico, corroborando a hipótese do estresse higrotérmico/nutricional. Os resultados indicam que os fatores locais podem ser importantes estruturadores da comundade de insetos galhadores em B. concinna.Item A diversidade padronizada.(1998) Carneiro, Marco Antonio Alves; Souza, Og Francisco Fonseca de; Fernandes, Geraldo Wilson Afonso; Lara, Angela C. F.Item Effect of tree size and growth form on the presence and activity of arboreal termites (Insecta: Isoptera) in the Atlantic Rain Forest.(2014) Gonçalves, Teresa Telles; Souza, Og Francisco Fonseca de; Reis Júnior, Ronaldo; Ribeiro, Sérvio PontesDespite the well known diversity of termites capable of inhabiting arboreal environments, the determinants of tree exploitation by térmites remain largely unknown. Data collected on trees exploited by termites in Brazilian Atlantic rainforest, a hot spot of diversity, reveals that whereas termite presence on trees is positively related simply to tree size, termite activity within arboreal tunnels depends on tree size and growth form. This leads us to hypothesize that termites find large trees randomly but keep higher activity in large trees due to the availability of food and arboreal nesting sites.Item Levy flights and self-similar exploratory behaviour of termite workers: beyond model fitting.(2014) Miramontes, Octavio; Souza, Og Francisco Fonseca de; Paiva, Letícia Ribeiro de; Marins, Alessandra; Orozco, SirioAnimal movements have been related to optimal foraging strategies where self-similar trajectories are central. Most of the experimental studies done so far have focused mainly on fitting statistical models to data in order to test for movement patterns described by power-laws. Here we show by analyzing over half a million movement displacements that isolated termite workers actually exhibit a range of very interesting dynamical properties –including Levy flights– in their exploratory behaviour. Going beyond the current trend of statistical model fitting alone, our study analyses anomalous diffusion and structure functions to estimate values of the scaling exponents describing displacement statistics. We evince the fractal nature of the movement patterns and show how the scaling exponents describing termite space exploration intriguingly comply with mathematical relations found in the physics of transport phenomena. By doing this, we rescue a rich variety of physical and biological phenomenology that can be potentially important and meaningful for the study of complex animal behavior and, in particular, for the study of how patterns of exploratory behaviour of individual social insects may impact not only their feeding demands but also nestmate encounter patterns and, hence, their dynamics at the social scale.Item Metal bioaccumulation alleviates the negative efects of herbivory on plant growth.(2021) Dueli, Grazieli de França; Souza, Og Francisco Fonseca de; Ribeiro, Sérvio PontesMetalliferous soils can selectively shape plant species’ physiology towards tolerance of high metal concentrations that are usually toxic to organisms. Some adapted plant species tolerate and accumulate metal in their tissues. These metals can serve as an elemental defence but can also decrease growth. Our investigation explored the capacity of natural metal accumulation in a tropical tree species, Eremanthus erythropappus (Asteraceae) and the efects of such bioaccumulation on plant responses to herbivory. Seedlings of E. erythropappus were grown in a glasshouse on soils that represented a metal concentration gradient (Al, Cu, Fe, Mn and Zn), and then the exposed plants were fed to the herbivores in a natural habitat. The efect of herbivory on plant growth was signifcantly mediated by foliar metal ion concentrations. The results suggest that herbivory efects on these plants change from negative to positive depending on soil metal concentration. Hence, these results provide quantitative evidence for a previously unsuspected interaction between herbivory and metal bioaccumulation on plant growth.Item Predation and interference competition between ants (Hymenoptera: Formicidae) and arboreal termites (Isoptera: Termitidae).(2005) Gonçalves, Teresa Telles; Reis Júnior, Ronaldo; Souza, Og Francisco Fonseca de; Ribeiro, Sérvio PontesOne of the most apparent biological interactions affecting termites is predation by vertebrates and invertebrates. Ants are the most important predators of other invertebrates and are the most active and effective predators of termites. Also, ants and termites might heavily compete for nesting space. Considering the potential of ants as competitors and predators of termites and the scarce knowledge of how they interact we tested the effects of the presence of ants on the activity of arboreal termites. Predatory ants had a negative effect on arboreal termite activity, and non-predatory ants had no effect. Specialized predatory ants are an important disturbance factor in resource exploitation by termites. Perhaps competition with non-predatory ants did not occur in our study because the foraging territories of ants and termites maybe do not overlap. Hence, it is clear that predation has a big impact on activity of termites, but the role of competition in shaping termite communities still needs further study, especially the competitive interaction between termites and ants.Item Sex-mediated herbivory by galling insects on Baccharis concinna (Asteraceae).(2006) Carneiro, Marco Antonio Alves; Fernandes, Geraldo Wilson Afonso; Souza, Og Francisco Fonseca de; Souza, Wyller Vicente M.Herbivoria por insetos galhadores mediada pelo sexo em Baccharis concinna (Asteraceae). Os padrões de interação entre o arbusto dióico Baccharis concinna Barroso (Asteraceae) e sua diversa comunidade de insetos galhadores foram estudados na região sudeste do Brasil. Duas hipóteses foram testadas neste estudo: “a hipótese do crescimento e reprodução diferenciais”, que prevê que plantas masculinas apresentam menos estruturas reprodutivas e são maiores do que plantas femininas; e a “hipótese da herbivoria mediada pelo sexo” que prevê que plantas masculinas sustentam uma maior abundância de insetos galhadores do que plantas femininas. Plantas não apresentaram dimorfismo sexual em relação ao crescimento (= número médio de folhas). Entretanto, plantas masculinas apresentaram ramos maiores e menor número de inflorescências do que plantas femininas. Estes resultados corroboram a hipótese que plantas masculinas crescem mais e se reproduzem menos do que plantas femininas. Nenhuma diferença estatisticamente significativa foi encontrada no número de galhas de insetos entre plantas masculinas e femininas, mas um efeito do sexo via meio ambiente sobre o número de galhas foi detectado. Quando cada espécie de inseto galhador em cada população da planta hospedeira foi analisada individualmente, as taxas de ataque variaram entre o sexo e a população da planta hospedeira, e estas taxas foram altamente variáveis entre as espécies de insetos galhadores. Estes resultados destacam a importância da interação entre o sexo e o meio ambiente na estrutura da comunidade de insetos galhadores e indicam que outras variáveis além do sexo da planta hospedeira podem influenciar os padrões de ataque por insetos galhadores.