Terrestrial arthropods from tree canopies in the Pantanal of Mato Grosso, Brazil

Terrestrial arthropods from tree canopies in the Pantanal of Mato Grosso, Brazil. This study represents a contribution to the knowledge of the diversity of arthropods associated to the canopy of Vochysia divergens Pohl (Vochysiaceae). Three trees individuals were sampled during two seasonal periods in this region: a) by spraying one tree canopy during high water (February); b) by fogging two tree canopies during low water (September/October). The 15,744 arthropods (183.2±38.9 individuals/m²) obtained from all three trees (86 m²) represented 20 taxonomic orders, 87.1% were Insecta, and 12.9% Arachnida. The dominant groups were Hymenoptera (48.5%; 88.9 individuals/m²), mostly Formicidae (44.5%; 81.4 individuals/m²), followed by Coleoptera (14.0%; 25.5 individuals/m²) and Araneae (10.2%; 19.5 individuals/m²), together representing 62.5% of the total catch. Fourteen (70%) of all orders occurred on three trees. Dermaptera, Isoptera, Neuroptera, Odonata, Plecoptera and Trichoptera were collected from only one tree. Of the total, 2,197 adult Coleoptera collected (25.5±11.3 individuals/m²), 99% were assigned to 32 families and 256 morphospecies. Nitidulidae (17.9% of the total catch; 4.6 individuals/m²), Anobiidae (16.7%; 4.3 individuals/m²), Curculionidae (13.2%; 3.4 individuals/m²) and Meloidae (11.4%; 2.9 individuals/m²) dominated. The communitiy of adult Coleoptera on V. divergens indicated a dominance of herbivores (37.8% of the total catch, 127 spp.) and predators (35.2%, 82 spp.), followed by saprophages (16.2%, 32 spp.) and fungivores (10.8%, 15 spp.). The influence of the flood pulse on the community of arboreal arthropods in V. divergens is indicated by the seasonal variation in evaluated groups, causing changes in their structure and composition.

Breeding sites of drosophilids (Diptera) in the Brazilian Savanna. I. Fallen fruits of Emmotum nitens (Icacinaceae), Hancornia speciosa (Apocynaceae) and Anacardium humile (Anacardiaceae)

In this study, drosophilids that bred in fruits of three common plant species of the Brazilian Savanna were investigated: Emmotum nitens, Hancornia speciosa and Anacardium humile, along with the temporal and spatial distribution of these insects among fruits obtained from six individuals of E. nitens. Fallen fruits were collected in natural environments, placed on moist sand in individual containers and all drosophilids that emerged from these resources during 15 days were collected, counted and identified. From 3,651 fruits collected (3,435 of E. nitens, 179 of A. humile and 37 of H. speciosa) 4,541 flies emerged and were classified into 19 species of Drosophilidae. Their distribution was unequal among the three resources, also over time, and among the six individuals of E. nitens. Such fluctuations probably reflect the availability of resources in time and space and probably the action of selective factors such as larval competition.

Within tree distribution of a gall-inducing Eurytoma (Hymenoptera, Eurytomidae) on Caryocar brasiliense (Caryocaraceae)

For the first time, we identified the insect herbivore that induces one of the most conspicuous galls on the leaves of Caryocar brasiliense Camb. (Caryocaraceae), a widespread, typical cerrado woody plant of large economic importance. The gall inducing organism is a new and undescribed species of Eurytoma sp. (Hymenoptera, Eurytomidae). Furthermore, we recorded its spatial distribution within C. brasiliense trees. More Eurytoma galls were found on the eastern tree slope, followed the southern and northern slopes. More galls were found in the interior of the tree crown, i.e., on the proximal portion of the stems compared to the terminal portion. At the leaf level, more galls were found on the median region compared to the distal or proximal, perhaps due to the lower trichome density found in there. Leaf colonization by Eurytoma sp. may initiate at the leaf margin but after colonization reaches 50% the central portion starts to be colonized.

Biological cycle of Tenuipalpus heveae Baker (Acari, Tenuipalpidae) on leaflets of three rubber tree clones

Life cycle of Tenuipalpus heveae Baker (Acari, Tenuipalpidae) on leaflets from three rubber tree clones. The biological cycle of Tenuipalpus heveae Baker, 1945 (Tenuipalpidae), a potential rubber tree pest mite, was studied by the observation of individuals reared on leaflets of the clones GT 1, PB 235 and RRIM 600, in controlled environmental conditions. Three daily observations were done of 60 eggs on leaflets from each clone in order to verify the development of immature stages and the female oviposition. The fertility life table was constructed based in the collected data. Mites reared on PB 235 had faster rate of development, requiring less time in days, to double its population in number (TD), and had the highest values for egg production, female longevity, net reproductive rate (Ro), intrinsic rate of natural increase (r m) and finite rate of increase (λ). Lower reproductive values and the longest time necessary to reach adult stage were recorded for the mites on GT 1. In all studied clones, the deutonymphal phase had the highest viability, while the larval phase had the lowest, highlighted by the survivorship curve that indicated high mortality during this life stage. The clone PB 235 allowed the most suitable conditions for the development of T. heveae, followed by RRIM 600, while GT 1 was the less suitable substratum to rear this mite species.

Spatial evaluation of larvae of Culicidae (Diptera) from different breeding sites: application of a geospatial method and implications for vector control

Spatial evaluation of Culicidae (Diptera) larvae from different breeding sites: application of a geospatial method and implications for vector control. This study investigates the spatial distribution of urban Culicidae and informs entomological monitoring of species that use artificial containers as larval habitats. Collections of mosquito larvae were conducted in the São Paulo State municipality of Santa Bárbara d' Oeste between 2004 and 2006 during house-to-house visits. A total of 1,891 samples and nine different species were sampled. Species distribution was assessed using the kriging statistical method by extrapolating municipal administrative divisions. The sampling method followed the norms of the municipal health services of the Ministry of Health and can thus be adopted by public health authorities in disease control and delimitation of risk areas. Moreover, this type of survey and analysis can be employed for entomological surveillance of urban vectors that use artificial containers as larval habitat.

A new genus and species of leaf miner (Lepidoptera, Gracillariidae) for Chile associated to the native tree Lithraea caustica

A new genus and species of leaf miner (Lepidoptera, Gracillariidae) for Chile associated to the native tree Lithraea caustica. We propose the new genus and species of Gracillariidae (Lepidoptera) Hualpenia lithraeophaga Mundaca, Parra &Vargas gen. nov., sp. nov., leaf miner of Lithraea caustica (Mol.) H. et Arn (Anacardiaceae) occurring in southern central Chile. Aspects of the life cycle, adult and larval morphology, development and feeding habits of the new genus and species are also presented. We emphasise the uniqueness and importance of this new species for broadening the current knowledge on the Chilean fauna of Gracillariidae.

Foraging strategies of the ant Ectatomma vizottoi (Hymenoptera, Formicidae)

Foraging strategies of the ant Ectatomma vizottoi (Hymenoptera, Formicidae). Foraging activity may be limited by temperature, humidity, radiation, wind, and other abiotic factors, all of which can affect energy costs during foraging. Ectatomma vizottoi's biology has only recently been studied, and no detailed information is available on its foraging patterns or diet in the field. For this reason, and because foraging activity is an important part of the ecological success of social insects, the present study aimed to investigate E. vizottoi's foraging strategies and dietary habits. First, we determined how abiotic factors constrained E. vizottoi's foraging patterns in the field by monitoring the foraging activity of 16 colonies on eight different days across two seasons. Second, we characterized E. vizottoi's diet by monitoring another set of 26 colonies during peak foraging activity. Our results show that E. vizottoi has foraging strategies that are similar to those of congeneric species. In spite of having a low efficiency index, colonies adopted strategies that allowed them to successfully obtain food resources while avoiding adverse conditions. These strategies included preying on other ant species, a foraging tactic that could arise if a wide variety of food items are not available in the environment or if E. vizottoi simply prefers, regardless of resource availability, to prey on other invertebrates and especially on other ant species.

Observations on the biology and distribution of Uresiphita reversalis (Lepidoptera, Crambidae), a defoliator of the native tree Calia secundiflora in México

Observations on the biology and distribution of Uresiphita reversalis (Lepidoptera, Crambidae), a defoliator of the native tree Calia secundiflora in México. Uresiphita reversalis (Guenée, 1854) feeding on Calia secundiflora (Ortega) Yakovlev is recorded for the first time in the state of Hidalgo, Mexico. New aspects regarding the life cycle, feeding behaviour, geographical distribution and host plant damage by U. reversalis on C. secundiflora are here presented and discussed.

Sampling strategies for tropical forest nutrient cycling studies: a case study in São Paulo, Brazil

The precise sampling of soil, biological or micro climatic attributes in tropical forests, which are characterized by a high diversity of species and complex spatial variability, is a difficult task. We found few basic studies to guide sampling procedures. The objective of this study was to define a sampling strategy and data analysis for some parameters frequently used in nutrient cycling studies, i. e., litter amount, total nutrient amounts in litter and its composition (Ca, Mg, Κ, Ν and P), and soil attributes at three depths (organic matter, Ρ content, cation exchange capacity and base saturation). A natural remnant forest in the West of São Paulo State (Brazil) was selected as study area and samples were collected in July, 1989. The total amount of litter and its total nutrient amounts had a high spatial independent variance. Conversely, the variance of litter composition was lower and the spatial dependency was peculiar to each nutrient. The sampling strategy for the estimation of litter amounts and the amount of nutrient in litter should be different than the sampling strategy for nutrient composition. For the estimation of litter amounts and the amount of nutrients in litter (related to quantity) a large number of randomly distributed determinations are needed. Otherwise, for the estimation of litter nutrient composition (related to quality) a smaller amount of spatially located samples should be analyzed. The determination of sampling for soil attributes differed according to the depth. Overall, surface samples (0-5 cm) showed high short distance spatial dependent variance, whereas, subsurface samples exhibited spatial dependency in longer distances. Short transects with sampling interval of 5-10 m are recommended for surface sampling. Subsurface samples must also be spatially located, but with transects or grids with longer distances between sampling points over the entire area. Composite soil samples would not provide a complete understanding of the relation between soil properties and surface dynamic processes or landscape aspects. Precise distribution of Ρ was difficult to estimate.

Influence of tree species on the herbaceous understory and soil chemical characteristics in a silvopastoral system in semi-arid northeastern Brazil

Studies from some semi-arid regions of the world have shown the beneficial effect of trees in silvopastoral systems, by promoting the formation of resource islands and increasing the sustainability of the system. No data are available in this respect for tree species of common occurrence in semi-arid Northeastern Brazil. In the present study, conducted in the summer of 1996, three tree species (Zyziphus joazeiro, Spondias tuberosa and Prosopis juliflora: ) found within Cenchrus ciliaris pastures were selected to evaluate differences on herbaceous understory and soil chemical characteristics between samples taken under the tree canopy and in open grass areas. Transects extending from the tree trunk to open grass areas were established, and soil (0-15 cm) and herbaceous understory (standing live biomass in 1 m² plots) samples were taken at 0, 25, 50, 100, 150 and 200% of the average canopy radius (average radius was 6.6 ± 0.5, 4.5 ± 0.5, and 5.3 ± 0.8 m for Z. joazeiro, P. juliflora, and S. tuberosa , respectively). Higher levels of soil C, N, P, Ca, Mg, K, and Na were found under the canopies of Z. joazeiro and P. juliflora: trees, as compared to open grass areas. Only soil Mg organic P were higher under the canopies of S. tuberosa trees, as compared to open grass areas. Herbaceous understory biomass was significantly lower under the canopy of S. tuberosa and P. juliflora trees (107 and 96 g m-2, respectively) relatively to open grass areas (145 and 194 g m-2). No herbaceous biomass differences were found between Z. joazeiro canopies and open grass areas (107 and 87 g m-2, respectively). Among the three tree species studied, Z. joazeiro was the one that presented the greatest potential for use in a silvopastoral system at the study site, since it had a larger nutrient stock in the soil without negatively affecting herbaceous understory biomass, relatively to open grass areas.

Biomass and nutrient cycling in pure and mixed stands of native tree species in southeastern Bahia, Brazil

The objective of this paper is to study selected components of the nutrient cycle of pure and mixed stands of native forest species of Atlantic Forest in southeastern Brazil. Tree diameter, height, above-ground biomass, and nutrient content were determined in 22-year-old stands. Litterfall, litter decomposition, and nutrient concentration were evaluated from August 1994 to July 1995. The following species were studied: Peltogyne angustiflora, Centrolobium robustum, Arapatiella psilophylla, Sclerolobium chrysophyllum, Cordia trichotoma, Macrolobium latifolium. The litter of a natural forest and a 40-year-old naturally regenerated second-growth forest was sampled as well. The mixed-species outmatched pure stands in height, stem volume and total biomass (29.4 % more). The greatest amount of forest litter was observed in the natural forest (9.3 Mg ha-1), followed by the mixed-species stand (7.6 Mg ha-1) and secondary forest (7.3 Mg ha-1), and least litterfall was measured in the pure C. robustum stand (5.5 Mg ha-1). Litterfall seasonality varied among species in pure stands (CV from 44.7 to 91.4 %), unlike litterfall in the mixed-tree stand, where the variation was lower (CV 31.2 %). In the natural and second-growth forest, litterfall varied by 57.8 and 34.0 %, respectively. The annual rate of nutrient return via litterfall varied widely among forest ecosystems. Differences were detected between forest ecosystems in both the litter accumulation and quantity of litterlayer nutrients. The highest mean nutrient accumulation in above-ground biomass was observed in mixed-species stands. The total nutrient accumulation (N + P + K+ Ca + Mg) ranged from 0.97 to 1.93 kg tree-1 in pure stands, and from 1.21 to 2.63 kg tree-1 in mixed-species stands. Soil fertility under mixed-species stands (0-10 cm) was intermediate between the primary forest and pure-stand systems. The litterfall rate of native forest species in a mixed-species system is more constant, resulting in a more continuous decomposition rate. Consequently, both nutrient availability and quantity of organic matter in the soil are higher and the production system ecologically more sustainable.

Heavy metals in soils and plants in mango orchards in Petrolina, Pernambuco, Brazil

The monitoring of heavy metal concentrations in areas under intensive agriculture is essential for the agricultural sustainability and food safety. This paper evaluates the total contents of heavy metals in soils and mango trees in orchards of different ages (6, 7, 8, 9, 10, 11, 14, 16, 17, 19, and 26 years) in Petrolina, Pernambuco, Brazil. Soil samples were taken from the layers 0-20 cm and 20-40 cm, and mango leaves were collected in the growth stage. Areas of native vegetation (Caatinga) adjacent to the cultivated areas were used for comparison. The total concentrations of heavy metals (Cu, Cr, Fe, Zn, Mn, Ni, and Pb) were determined in soils and leaves. In general, mango cultivation led to Cu and Zn accumulation in the soil surface and to a reduction in the contents of Ni, Pb, Mn, and Fe in surface and subsurface. Since contamination by Cu, Zn, and Cr was detected, these areas must be monitored to prevent negative environmental impacts. For instance, the presence of Cr in mango tree leaves indicates the need to investigate the source of the element in these orchards. The management strategies of the different companies led to deficiency or excess of some metals in the evaluated areas. However, the Fe and Mn levels were adequate for the mineral nutrition of mango in all areas.

Quantification of the least limiting water range in an oxisol using two methodological strategies

The least limiting water range (LLWR) has been used as an indicator of soil physical quality as it represents, in a single parameter, the soil physical properties directly linked to plant growth, with the exception of temperature. The usual procedure for obtaining the LLWR involves determination of the water retention curve (WRC) and the soil resistance to penetration curve (SRC) in soil samples with undisturbed structure in the laboratory. Determination of the WRC and SRC using field measurements (in situ ) is preferable, but requires appropriate instrumentation. The objective of this study was to determine the LLWR from the data collected for determination of WRC and SRC in situ using portable electronic instruments, and to compare those determinations with the ones made in the laboratory. Samples were taken from the 0.0-0.1 m layer of a Latossolo Vermelho distrófico (Oxisol). Two methods were used for quantification of the LLWR: the traditional, with measurements made in soil samples with undisturbed structure; and in situ , with measurements of water content (θ), soil water potential (Ψ), and soil resistance to penetration (SR) through the use of sensors. The in situ measurements of θ, Ψ and SR were taken over a period of four days of soil drying. At the same time, samples with undisturbed structure were collected for determination of bulk density (BD). Due to the limitations of measurement of Ψ by tensiometer, additional determinations of θ were made with a psychrometer (in the laboratory) at the Ψ of -1500 kPa. The results show that it is possible to determine the LLWR by the θ, Ψ and SR measurements using the suggested approach and instrumentation. The quality of fit of the SRC was similar in both strategies. In contrast, the θ and Ψ in situ measurements, associated with those measured with a psychrometer, produced a better WRC description. The estimates of the LLWR were similar in both methodological strategies. The quantification of LLWR in situ can be achieved in 10 % of the time required for the traditional method.

HEAVY METALS AND MICRONUTRIENTS IN THE SOIL AND GRAPEVINE UNDER DIFFERENT IRRIGATION STRATEGIES

Soils under natural conditions have heavy metals in variable concentrations and there may be an increase in these elements as a result of the agricultural practices adopted. Transport of heavy metals in soil mainly occurs in forms dissolved in the soil solution or associated with solid particles, water being their main means of transport. In this context, the aim of this study was to evaluate the heavy metal and micronutrient content in the soil and in the grapevine plant and fruit under different irrigation strategies. The experiment was carried out in Petrolina, PE, Brazil. The treatments consisted of three irrigation strategies: full irrigation (FI), regulated deficit irrigation (RDI), and deficit irrigation (DI). During the period of grape maturation, soil samples were collected at the depths of 0-10, 10-20, 20-40, 40-60, and 60-80 cm. In addition, leaves were collected at the time of ripening of the bunches, and berries were collected at harvest. Thus, the heavy metal and micronutrient contents were determined in the soil, leaves, and berries. The heavy metal and micronutrient contents in the soil showed a stochastic pattern in relation to the different irrigation strategies. The different irrigation strategies did not affect the heavy metal and micronutrient contents in the vine leaves, and they were below the contents considered toxic to the plant. In contrast, the greater availability of water in the FI treatment favored a greater Cu content in the grape, which may be a risk to vines, causing instability and turbidity. Thus, adoption of deficit irrigation is recommended so as to avoid compromising the stability of tropical wines of the Brazilian Northeast.

Contrasts in Areas of Rubber Tree Clones in Regard to Soil and Biomass Carbon Stocks

ABSTRACT Rubber tree (Hevea brasiliensis) crop may accumulate significant amounts of carbon either in biomass or in the soil. However, a comprehensive understanding of the potential of the C stock among different rubber tree clones is still distant, since clones are typically developed to exhibit other traits, such as better yield and disease tolerance. Thus, the aim of this study was to address differences among different areas planted to rubber clones. We hypothesized that different rubber tree clones, developed to adapt to different environmental and biological constrains, diverge in terms of soil and plant biomass C stocks. Clones were compared in respect to soil C stocks at four soil depths and the total depth (0.00-0.05, 0.05-0.10, 0.10-0.20, 0.20-0.40, and 0.00-0.40 m), and in the different compartments of the tree biomass. Five different plantings of rubber clones (FX3864, FDR 5788, PMB 1, MDX 624, and CDC 312) of seven years of age were compared, which were established in a randomized block design in the experimental field in Rio de Janeiro State. No difference was observed among plantings of rubber tree clones in regard to soil C stocks, even considering the total stock from 0.00-0.40 m depth. However, the rubber tree clones were different from each other in terms of total plant C stocks, and this contrast was predominately due to only one component of the total C stock, tree biomass. For biomass C stock, the MDX 624 rubber tree clone was superior to other clones, and the stem was the biomass component which most accounted for total C biomass. The contrast among rubber clones in terms of C stock is mainly due to the biomass C stock; the aboveground (tree biomass) and the belowground (soil) compartments contributed differently to the total C stock, 36.2 and 63.8 %, respectively. Rubber trees did not differ in relation to C stocks in the soil, but the right choice of a rubber clone is a reliable approach for sequestering C from the air in the biomass of trees.