Glycaspis brimblecombei Moore is an Australian native pest of Eucalyptus detected in Brazil in 2003. Since then, it has spread fast and colonized plantations in several states of the country. This study aimed to investigate the influence of cerrado remnants on the abundance and biological control of G. brimblecombei. We placed yellow sticky card traps to capture insects in four plantations of hybrid clones of Eucalyptus urophylla x Eucalyptus grandis ("Urograndis") and four plantations of E. urophylla x Eucalyptus camaldulensis ("Urocam"). Traps were placed in three areas of these plantations: center, border with cerrado and border without cerrado. We also collected leaves from the same clones to estimate psyllid egg and lerp abundance. The abundance of G. brimblecombei was lower in the plantation-cerrado border, and the inverse pattern was observed for microhymenopterans. The leaf abaxial surface showed a higher abundance of eggs and nymphs, probably as a consequence of a lower parasitism rate and mechanical removal by wind and rain. Egg number was higher on Urograndis than in Urocam clones, but the number of psyllid lerps was higher in the latter. Thus, the establishment of first instars is probably a critical event to psyllid infestation, and these differences may be caused by morphological, anatomical and biochemical leaf features of distinct clones. Our results suggest that the maintenance of native vegetation around plantations is a promising management practice to promote the natural biological control of G.brimblecombei, a strategy that would also enhance the preservation of cerrado remnants.

Este estudo testou a eficiência de formigas como dispersores secundários de Ricinus communis no Brasil. Em uma população natural de 143 indivíduos, a distância de dispersão balística foi determinada para 62 sementes. Além disso, 100 sementes adicionais foram oferecidas a formigas em grupos de 10, ao longo de um transecto de 50 m. Cinqüenta e três sementes foram removidas por formigas, principalmente pela formiga-cortadeira Atta sexdens (90,4%). A distância de dispersão por formigas foi alta se comparada à média global (4,38m ± 0,74 m vs. 0,96 m), porém menor que a distância de dispersão balística (7,27 m ± 0,13 m). As formigas aumentaram a distância de dispersão total (8,66 m ± 0,60 m), mas o principal benefício para a planta foi a dispersão direcionada, com a deposição das sementes no solo enriquecido encontrado nos ninhos das formigas.

In this study, I tested the efficacy of ants as secondary seed dispersers of Ricinus communis in southeastern Brazil. In a natural population of 143 individuals, I determined the ballistic dispersal distance for 62 seeds and 100 additional seeds were experimentally offered to ants in groups of ten seeds along a transect of 50 m. Fifty-three seeds were removed by ants, mainly by the leafcutter Atta sexdens (90.4%). The dispersal distance by ants was high, compared to the global average (4.38 m ± 0.74 m vs. 0.96 m), but was lower than the ballistic distance (7.27 m ± 0.13 m). Ants increased the total dispersal distance (8.66 m ± 0.60 m), but the main benefit for the plant was the directed dispersal, with seed deposition on the enriched soil of ant nests.

Este trabalho teve como objetivo comparar o padrão de distribuição, abundância e tamanho de Drosera montana em microhabitats sob diferentes condições de umidade do solo e cobertura vegetal na Serra do Cipó, MG. Foi analisado um transecto de 15x3m, no qual foram mapeados e medidos todos os indivíduos encontrados, e calculados os índices de agregação de Clark & Evans e de Hopkins. O transecto foi dividido em 45 quadrados de lm², nos quais foram coletadas amostras de solo e medidas suas percentagens de umidade. A percentagem de cobertura vegetal foi estimada pelo método de Daumbemirre para cada quadrado. D. montana apresentou padrão de distribuição agregado. A maior abundância de indivíduos ocorreu em locais de umidade e cobertura vegetal intermediárias, em um contínuo de condições ambientais variando de locais de solo seco com pouca cobertura vegetal a locais de solo muito úmido com muita cobertura. Entretanto, o tamanho de D. montana não parece ser afetado pela umidade ou cobertura vegetal, sendo provavelmente determinado pelo sucesso de captura de presas. Estes resultados sugerem que o padrão agregado observado para esta espécie está relacionado à disponibilidade de água e luz, mas seu crescimento é possivelmente influenciado pela interação entre fatores bióticos e abióticos.

This study aimed at comparing the distribution, abundance and size of Drosera montana in microhabitats under different conditions of soil humidity and vegetation cover in Serra do Cipó, state of Minas Gerais. In a transect of 15x3m, all individuals of D. montana were mapped and their diameters were measured. We calculated the aggregation indexes of Clark & Evans and of Hopkins. The transect was divided into 45 quadrats of lm². Soil samples were collected in each quadrat for moisture content determination. The percentage of vegetation cover was estimated for each quadrat using the method of Daumbemirre. D. montana presented an aggregated pattern of distribution. A higher abundance of individuals was observed on sites with intermediate soil humidity and vegetation cover, in a continuum of environmental conditions varying from sites with dry soils and low vegetation cover to sites with wet soils and high vegetation cover. However, the size of D. montana was apparently not affected by soil humidity or vegetation cover, and is probably determined by prey trapping success. These results suggest that the aggregated pattern observed for this species is related to water and light availability, but its growth is possibly influenced by an interaction of biotic and abiotic factors.

Vários fatores ecológicos, genéticos e ambientais podem influenciar a concentração de taninos em tecidos de uma planta. Neste estudo, os efeitos da sazonalidade, disponibilidade de água e sexo da planta sobre a concentração de taninos no arbusto dióico Baccharis dracunculifolia foram avaliados. Também foram verificados os efeitos da disponibilidade de água sobre o crescimento de ramos da planta e a relação com a concentração de taninos. Os indivíduos de B. dracunculifolia produziram taninos de novembro a maio, apresentando maiores concentrações durante o verão (dezembro a março). Entretanto, não foram encontradas relações entre a concentração de taninos e a precipitação e a temperatura, assim como também não foram observadas diferenças na concentração de taninos e crescimento de ramos entre plantas irrigadas e controle, sugerindo que a produção dessas substâncias seja afetada por outros fatores, como intensidade de luz ou fenologia da planta. Houve relação negativa entre a concentração de taninos e o crescimento de ramos, possivelmente em virtude de um "trade-off' entre estas atividades metabólicas. Não foram observadas diferenças intersexuais na concentração de taninos e crescimento de ramos, indicando que B. dracunculifolia não apresenta distribuição diferencial de recursos entre indivíduos masculinos e femininos.

Several ecological, genetic, and environmental factors are known to influence tannin concentration in plant tissues. In this study, the effects of seasonality, water availability, and sex of the plant on tannin concentration in the dioecious shrub Baccharis dracunculifolia were assessed. The effects of water availability on plant shoot growth and its relationship to tannin concentration were also experimentally evaluated. Tannins occurred in B. dracunculifolia from November to May, peaking during the summer (December to March). However, no relationship between tannin concentration, rainfall and temperature was found. No difference in tannin concentration and shoot growth was found between plants in the irrigated and control treatments, this suggesting that tannin production was affected by factors other than water availability, such as light intensity or plant phenology. There was a negative relationship between tannin concentration and shoot growth, possibly due to a trade-off between these metabolic activities. Plant gender did not influence tannin concentration and shoot growth, indicating that B. dracunculifolia did not show a differential resource allocation between male and female individuals.