DEBIO - Artigos publicados em periódicos

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Influence of experimental illumination and seasonal variation on crossbreeding matinf in the snail Biomphalaria glabrata.
(1988) Souza, Fernando Pimentel; Schall, Virgínia Torres; Barbosa, Norma Dulce de Campos; Souza, Mauro Schettino de; Lautner Júnior, Rodolfo
The crossbreeding activities of the Schistosoma mansoni vector snail Biomphalaria glabrata were counted in a laboratory aquarium throughout the year under two regimes of 12h light: 12h dark from 7 A., M. to 10 P. M. Mating increased significantly in Authmn and Winter and just missed a significant inverse correlation with temperature and a direct one with locomotion. Other similar experiments were carried out to compare mating under various ilumination conditions in complete daily cycle measurements. Mating counts decreased under the regimes which submited snail to a total exposure of 12h light and 12 dark during a daily cycle in the following sequence: 12h light: 12h dark alternating hourly with light gradient, 12h light: 12h dark, 1h light: 1h dark and 12h dark: 12h light. Under two constant illuminations, the mating scored less than under the previous conditions, except under 12h light. Under darkeness the mating count was lower than light conditions. There was no way to differentiate the night and day rhythms of mating on different days in each regime, except for mating under 12h light: 12 dark alternating with light gradient, constant dark and 12h dark: 12h light conditions. Mating increased in certain light and temperature conditions, in wich the intensities, should have an optimum value.
Métodos de Coloração de Roeser (1972) modificado e Kropp (1972) visando a substituição do azul de astra por azul de alcião 8GS e 8GX.
(1996) Luquel, Rebeca; Sousa, Hildeberto Caldas de; Kraus, Jane Elizabeth
(Métodos de coloração de Roeser (l972) - modificado - e Kropp (1972) visando a substituição do azul de astra por azul de alcião 8GS ou 8GX). Em folhas de Lychnophora ericoides, Coffea arabica e Nymphaea mexicana foram testados métodos de coloração baseados em Roeser (1972) modificado e Kropp (1972), visando a substituição do corante azul de astra por azul de alcião 8GS ou 8GX. As amostras foram fixadas em FAA, desidratadas em série butílica terciária e incluídas em parafina. Os cortes histológicos transversais foram corados segundo diferentes baterias de coloração, modificadas quanto ao tipo de corante usado, diferenciador e série de desidratação. As lâminas permanentes foram preparadas com bálsamo-do-canadá sintético. Os resultados obtidos evidenciaram que o método de Roeser (1972) modificado é melhor que o de Kropp (1972), nas condições deste experimento. O azul de astra pode ser substituído por azul de alcião 8GX e a desidratação pode ser em série isopropílica ou etílica, sem grande diferença entre elas. São discutidos os resultados provenientes das diferentes colorações.
A diversidade padronizada.
(1998) Carneiro, Marco Antonio Alves; Souza, Og Francisco Fonseca de; Fernandes, Geraldo Wilson Afonso; Lara, Angela C. F.
Free-feeding insect herbivores along environmental gradients in Serra do Cipó : basis for a management plan.
(1998) Ribeiro, Sérvio Pontes; Carneiro, Marco Antonio Alves; Fernandes, Geraldo Wilson Afonso
The distribution of free-feeding insect herbivores in Brazilian savanna was studied in the National Park of Serra do Cipó. Insect samples were obtained with sweep nets across cerrado (savanna), rupestrian field and altitudinal grassland vegetation from 800 to 1500 m above sea level. We found a low species richness in xeric and mesic habitats during both wet and dry seasons. Sapsucking insects were the most abundant guild (53.4%) with Cicadellidae the most abundant family (27.2%). The hypothesis that taxon richness of free-feeding insects decreases with increasing altitude was supported in xeric habitats during the wet season only, mainly as a function of mountain summit effect. There was a decrease of 65% in the number of families occurring at 1400 and 1500 m compared with lower elevations. The exclusion of sites of rupestrian vegetation at mid-elevations from the analysis increased significantly the proportion of variance explained by the model. An examination of taxon distribution using canonical variate analysis supported this result. The hypothesis that mesic habitats are richer in species of free-feeding insect herbivores than are xeric habitats was not supported. The data indicate that plant sclerophylly may exert a strong negative influence on insect species richness, and that variation due to particular characteristics of each site strongly affected the studied guilds. The present results should inform conservation strategies for the National Park Management Plan, which is currently being developed.
Distribution and morphology of insect galls of the Rio Doce Valley, Brazil.
(2001) Fernandes, Geraldo Wilson Afonso; Julião, Genimar Rebouças; Araújo, Raquel Costa; Araújo, Simone Costa; Lombardi, Júlio Antônio; Negreiros, Daniel; Carneiro, Marco Antonio Alves
Brazil has the talent : just let us get on with the job. Frustrated researchers are calling for support from the international scientific community.
(2001) Ribeiro, Sérvio Pontes; Mendonça Júnior, Milton de Souza; Barbosa, Edésio M.; Souza Neto, João Adauto de
Tree species monodominance or species-rich savannas : the influence of abiotic factors in designing plant communities of the Brazilian cerrado and the Pantanal matogrossense : a review.
(2002) Ribeiro, Sérvio Pontes; Brown, Valerie K.
Efeitos do sexo, do vigor e do tamanho da planta hospedeira sobre a distribuição de insetos indutores de galhas em Baccharis pseudomyriocephala Teodoro (Asteraceae).
(2003) Araújo, Ana Paula Albano; Carneiro, Marco Antonio Alves; Fernandes, Geraldo Wilson Afonso
Effects of gender, vigor and size of the host plant Baccharis pseudomyriocephala Teodoro (Asteraceae) on gallinducing insect distribution. Several hypotheses have been proposed to explain the patterns of host plant utilization by herbivorous insects in natural communities. We tested four hypotheses aiming to understand the pattern of attack by gallinducing insects on the dioecious shrub, Baccharis pseudomyriocephala (Asteraceae). The shrub occurs in the Parque Estadual do Itacolomi, Southeastern Brazil, and supports ten species of galling insects. The following hypotheses were tested: i) male plants are more attacked by galling insects than female plants; ii) larger plant modules are preferentially attacked by galling insects; iii) galling insects perform better on larger modules than on smaller modules; iv) galling insects increase in abundance with meristematic availability. To address these questions, 240 plants (120 of each sex) were sampled in both reproductive and vegetative periods. We recorded the growth rate (4 cm), inflorescence and fruit production, attack rates of the galling insects, and their survivorship and mortality per shoot (module). Modules were separated into size classes (cm) and analyzed by regressions and ANCOVAs. Module size and reproductive effort were positively correlated with host plant size. We did not observe any effect of host plant gender on either variables. In the same way, host plant sex did not show any influence on the abundance and richness of galling insects. Although the abundance of galling insects showed a positive correlation with shoot size, the trend disappeared when the analyses were performed taking into consideration the number of galls per unit of growth (number of galls/cm of shoot) or biomass (number of galls/dry weight). Larval survivorship was not influenced by shoot size. Also, we observed that the abundance of one species of hemipteran galling insect showed a positive relation with leaf biomass. Therefore, we conclude that gender and vigor of this plant species do not influence the community structure of its galling herbivores.
Ecology and evolution of the arborescent Erica azorica (Ericaceae).
(2003) Ribeiro, Sérvio Pontes; Borges, Paulo Alexandre Vieira; Gaspar, Clara
Papilionoideae (Leguminosae) nos campos ferruginosos do Parque Estadual do Itacolomi, Minas Gerais, Brasil : florística e fenologia.
(2005) Dutra, Valquiria Ferreira; Messias, Maria Cristina Teixeira Braga; Garcia, Flávia Cristina P.
(Papilionoideae (Leguminosae) dos campos ferruginosos do Parque Estadual do Itacolomi, MG). Foi realizado um levantamento florístico das espécies de Papilionoideae (Leguminosae) ocorrentes nos campos ferruginosos do Parque Estadual do Itacolomi (PEI), situado nos municípios de Ouro Preto e Mariana, estado de Minas Gerais. As coletas foram feitas no período de março de 2001 a maio de 2002. Foram identificadas 20 espécies de Papilionoideae, pertencentes a 13 gêneros. Os gêneros mais representativos em número de espécies foram Desmodium (4), Crotalaria (3), Machaerium e Stylosanthes, com duas espécies cada. Os demais gêneros foram representados por apenas uma espécie cada. No estudo fenológico das espécies, foram constatadas correlações entre fatores climáticos (temperatura e precipitação) e a perda de folhas, brotação, floração e frutificação.
Canopy insect herbivores in the Azorean Laurisilva forests : key host plant species in a highly generalist insect community.
(2005) Ribeiro, Sérvio Pontes; Borges, Paulo Alexandre Vieira; Gaspar, Clara; Melo, Catarina; Serrano, Artur R. M.; Amaral, João; Aguiar, Carlos A. S.; André, Genage; Quartau, José Alberto
This article explores patterns of insect herbivore distribution in the canopy of the Laurisilva forests on seven islands in the Azores archipelago. To our knowledge, this is one of the first extensive study of this type in tree or shrub canopies of oceanic island ecosystems. One of the most frequently debated characteristics of such ecosystems is the likely prevalence of vague, ill-defined niches due to taxonomic disharmony, which may have implications for insect-plant interactions. For instance, an increase in ecological opportunities for generalist species is expected due to the lack of predator groups and reduced selection for chemical defence in host plants. The following two questions were addressed: 1) Are specialists species rare, and insect herbivore species randomly distributed among host plant species in the Azores? 2) Are the variances in insect herbivore species composition, frequency and richness explained by host plants or by regional island effects? We expect a proportional distribution of herbivore species between host plants, influenced by host frequency and distinct island effects; otherwise, deviation from expectation might suggest habitat preference for specific host tree crowns. Canopy beating tray samples were performed on seven islands, comprising 50 transects with 1 to 3 plant species each (10 replicates per species), giving 1320 samples from ten host species trees or shrubs in total. From a total of 129 insect herbivore species, a greater number of herbivore species was found on Juniperus brevifolia (s /65) and Erica azorica (s /53). However, the number of herbivore species per individual tree crown was higher for E. azorica than for any other host, on all islands, despite the fact that it was only the fourth more abundant plant. In addition, higher insect species richness and greater insect abundance were found on the trees of Santa Maria Island, the oldest in the archipelago. Insect species composition was strongly influenced by the presence of E. azorica , which was the only host plant with a characteristic fauna across the archipelago, whereas the fauna of other plant crowns was grouped by islands. The great insect occurrence on E. azorica reflects strong habitat fidelity, but only four species were clearly specialists. Our findings indicate a broadly generalist fauna. The simplicity of Azorean Laurisilva contributed to the understanding of insect-plant mechanisms in canopy forest habitats.
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 Pontes
One 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.
Convergence in the variation of local and regional galling species richness.
(2005) Carneiro, Marco Antonio Alves; Fernandes, Geraldo Wilson Afonso; Souza, Og Francisco Fonseca de
Foram 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.
Genetic, morphological and spatial characterization of two populations of Mabea fistulifera mart. (Euphorbiaceae), in different successional stages.
(2005) Goulart, Maíra Figueiredo; Ribeiro, Sérvio Pontes; Lovato, Maria Bernadete
Two populations of Mabea fistulifera (Euphorbiaceae) located at Rio Doce State Park (Minas Gerais, Brazil) in places characterized as in different successional stages, were investigated through genetic and ecological traits. Twenty randomly chosen individuals from each population had its genetic data assessed by 43 RAPD markers and were also evaluated through five morphologic traits and its spatial distribution. Both Shannon’s index and AMOVA reveled that most of the genetic variation was found between individuals within populations and about 9% of variation was located between populations. Moreover, populations differed genetically, but presented similar values of genetic diversity. Morphologic data showed differences between populations. Significant correlations among matrix of genetic, geographic and morphologic distances were obtained considering both populations, and spatially closer individuals were more similar genetically, characterizing genetic substructured populations.
Effects of urbanization on Neotropical wasp and bee assemblages in a Brazilian metropolis.
(2005) Zanette, Lorenzo Roberto Sgobaro; Martins, Rogério Parentoni; Ribeiro, Sérvio Pontes
The rapid growth of cities in many parts of the world has stimulated an increasing number of ecological studies of urban environments. Here, 12 study sites in the city of Belo Horizonte (MG), southeastern Brazil, were compared to analyze the effects of habitat changes related to urbanization on the species richness and abundance of native wasps and bees. Two spatial scales were considered: large portions of the urban landscape (entire sites) and small areas within these sites (public squares). Overall, the abundance of advanced eusocial bees (i.e. stingless bees), which were the dominant species, was directly affected by the loss of vegetation cover and the increase of buildings associated with urbanization. The magnitude of this effect varied according to the nesting habits of each species. The loss of vegetation cover associated with urbanization also had a negative effect on the abundance and species richness of advanced eusocial wasps. Generalist species of bees and wasps, such as Trigona spinipes and Polybia occidentalis, were very abundant and not sensitive to the habitat changes related to urbanization. Advanced eusocial bees also responded to small-scale habitat changes (size and vegetation cover of public squares). No relation was found between the solitary and the primitive eusocial wasps and bees and the habitat changes considered here. Conservation strategies in urban environments need to consider different spatial scales in order to maintain or enhance the local diversity of wasps and bees.
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.
Prevalence of monodominant vigorous tree populations in the tropics : herbivory pressure on Tabebuia species in very different habitats.
(2006) Ribeiro, Sérvio Pontes; Brown, Valerie K.
We have studied the reproductive performance, early establishment and insect herbivory in two Tabebuia species found in contrasting distant habitats. Tabebuia ochracea and T. aurea are sympatric in the cerrado (Brazilian savanna), whereas T. aurea also colonizes floodplains in the wetlands of the ‘Pantanal Matogrossense’ as large monodominant stands, but is sparsely distributed in the cerrado.
Effects of host plant architecture on colonization by galling insects.
(2006) Araújo, Ana Paula Albano; Paula, Joana D’arc de; Carneiro, Marco Antonio Alves; Schoereder, José Henrique
To study the abundance and occurrence of herbivore insects on plants it is important to consider plant characteristics that may control the insects. In this study the following hypotheses were tested: (i) an increase of plant architecture increases species richness and abundance of gall-inducing insects and (ii) plant architecture increases gall survival and decreases parasitism. Two hundred and forty plants of Baccharis pseudomyriocephala Teodoro (Asteraceae) were sampled, estimating the number of shoots, branches and their biomass. Species richness and abundance of galling insects were estimated per module, and mortality of the galls was assessed. Plant architecture influenced positively species richness, abundance and survival of galls. However, mortality of galling insects by parasitoids was low (13.26%) and was not affected by plant architecture, thus suggesting that other plant characteristics (a bottom-up pressure) might influence gall-inducing insect communities more than parasitism (a top-down pressure). The opposite effect of herbivore insects on plant characteristics must also be considered, and such effects may only be assessed through manipulative experiments.
Effect of habitat structure on ant assemblages associated to two pioneer tree species (Hymenoptera : formicidae).
(2006) Campos, Ricardo Ildefonso de; Soares, Janaina Pizzatti; Martins, Rogério Parentoni; Ribeiro, Sérvio Pontes
The present study investigates the effects of ant species distributions among host tree crowns in response to surrounding habitat. It was developed at the State Park of Rio Doce, in the middle basin of the Doce river, South Eastern Brazil. The studied plants were Mabea fistulifera Mart. (Euphorbiaceae), a forest border ecotone pioneer species, and Byrsonima sericea DC. (Malphigiaceae), a forest-lake ecotone colonizer species. Ants were sampled on the tree crowns for using a beating device, during one dry and two wet seasons thus comparing ecotone and interior forest habitats. In total 335 ant individuals were collected belonging to 5 subfamilies, 15 genera and 40 species. A MANOVA model shows differences in species richness only for the wet season of 2001, where the mean number of ant species per tree was nearly double in the ecotones than in the forest, regardless of which host plant. Ant abundance did not differ between habitats (ecotone and forests), but Mabea fistulifera had, on average, three times more ant individuals on its crown than B. sericea in the wet season of 2001. In addition, this value found for M. fistulifera was higher than any other overall abundance estimate in the following dry or wet season. A discriminant analysis showed how the ant fauna composition was distinct in the artificial ecotone site between sampling periods, which demonstrate how a disturbance can modify the ant species composition in comparison with preserved habitats. However, the ant fauna on M. fistulifera in the interior forest and on B. sericea in the ecotone were more similar than any other sub-set of species, suggesting that micro-habitat ecological conditions and geological history could influence more ant species distribution than host plant or ecotone-interior contrasts.
Emissão de óxidos de nitrogênio associada à aplicação de ureia sob plantio convencional e direto.
(2006) Carvalho, Arminda Moreira de; Bustamante, Mercedes Maria da Cunha; Kozovits, Alessandra Rodrigues; Miranda, Leo Nobre de; Vivaldi, Lúcio José; Sousa, Danielle Matias de
O objetivo deste trabalho foi avaliar emissões de NO e N2O até cinco dias após a primeira fertilização de cobertura com uréia em milho, em Latossolo Vermelho argiloso distrófico, sob plantio convencional e direto. A adubação de cobertura foi de 60 kg ha-1 de N. O experimento foi conduzido na Embrapa Cerrados, Planaltina, DF, com delineamento de blocos ao acaso, com três repetições, sendo o terceiro cultivo de milho, em rotação com soja. Os fluxos de NO e N2O foram medidos em câmaras de PVC instaladas em cada parcela. Houve emissão alta de NO imediatamente após (5,4 ng N cm-2 h-1) e no terceiro dia (4,8 ng N cm-2 h-1) após aplicação de uréia e irrigação. Um dia após fertilização, a emissão de NO reduziu-se a 1,9 ng N cm-2 h-1, e cinco dias depois, alcançou 1,2 ng N cm-2 h-1. Os fluxos de N2O ficaram abaixo do limite de detecção de 0,6 ng N cm-2 h-1. Não houve diferença significativa entre os plantios convencional e direto quanto à emissão dos óxidos de nitrogênio.

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