Tropical Region Of Brazil Research Articles

Effects of harbor activities on sediment quality in a semi-arid region in Brazil

Tropical marine environments are rich in biodiversity and the presence of harbor activities in these areas can harm the coastal ecosystems. In this study, we assessed sediment quality of two harbors from a tropical region in Brazil by applying multiple lines-of-evidence approach. This approach included the integration of results on: (1) grain size, organic matter, organic carbon, nitrogen, phosphorus, trace metals, polycyclic aromatic hydrocarbons, linear alkylbenzenes, and tributyltin; (2) acute toxicity of whole sediments and chronic toxicity of liquid phases; and (3) benthic community descriptors. Our results revealed that the main contaminants detected in sediments from Mucuripe and Pecém Harbors were chromium, copper, nitrogen, zinc, and tributyltin. These toxicants arise from typical harbor activities. However, the changes in benthic composition and structure appear to depend on a combination of physical impacts, such as the deposition of fine sediments and the toxic potential of contaminants, especially in Mucuripe. Thus, apart from toxicants physical processes are important in describing risks. This information may assist in management and conservation of marine coastal areas.

Respiratory syncytial virus a and b display different temporal patterns in a 4-year prospective cross-sectional study among children with acute respiratory infection in a tropical city.

Respiratory syncytial virus (RSV) is one of the most common etiological agents of childhood respiratory infections globally. Information on seasonality of different antigenic groups is scarce. We aimed to describe the frequency, seasonality, and age of children infected by RSV antigenic groups A (RSVA) and B (RSVB) among children with ARI in a 4-year period.Children (6–23 months old) with respiratory infection for ≤7 days were enrolled in a prospective cross-sectional study, from September, 2009 to October, 2013, in Salvador, in a tropical region of Brazil. Upon recruitment, demographic, clinical data, and nasopharyngeal aspirates (NPA) were collected. A multiplex quantitative real-time polymerase chain reaction (RT-PCR) with a group-specific primer and probeset for RSVA and RSVB was used. Seasonal distribution of infection by RSV different antigenic groups was evaluated by Prais-Wisten regression.Of 560 cases, the mean age was 11.4 ± 4.5 months and there were 287 (51.3%) girls. Overall, RSV was detected in 139 (24.8%; 95% CI: 21.4%–28.5%) cases, RSVA in 74 (13.2%; 95% CI: 10.6%–16.2%) cases, and RSVB in 67 (12.0%; 95% CI: 9.5%–14.9%) cases. Two (0.4%; 95% CI: 0.06%–1.2%) cases had coinfection. RSVA frequency was 9.6%, 18.4%, 21.6%, and 3.1% in 2010, 2011, 2012, and 2013, respectively. RSVB frequency was 19.2%, 0.7%, 1.4%, and 35.4% in the same years. RSVA was more frequently found from August to January than February to July (18.2% vs. 6.4%, P < 0.001). RSVB was more frequently found (P < 0.001) between March and June (36.0%) than July to October (1.0%) or November to February (1.6%). RSVB infection showed seasonal distribution and positive association with humidity (P = 0.02) whereas RSVA did not. RSVA was more common among children ≥1-year-old (17.8% vs. 1.8%; P = 0.02), as opposed to RSVB (11.5% vs. 12.2%; P = 0.8).One quarter of patients had RSV infection. RSVA compromised more frequently children aged ≥1 year. RSVA predominated in 2011 and 2012 whereas RSVB predominated in 2010 and 2013. In regard to months, RSVA was more frequent from August to January whereas RSVB was more often detected between March and June. Markedly different monthly as well as yearly patterns for RSVA and RSVB reveal independent RSV antigenic groups’ epidemics.

Performance of Deterministic and Probabilistic Hydrological Forecasts for the Short-Term Optimization of a Tropical Hydropower Reservoir

Hydropower is the most important source of electricity in Brazil. It is subject to the natural variability of water yield. One building block of the proper management of hydropower assets is the short-term forecast of reservoir inflows as input for an online, event-based optimization of its release strategy. While deterministic forecasts and optimization schemes are the established techniques for short-term reservoir management, the use of probabilistic ensemble forecasts and multi-stage stochastic optimization techniques is receiving growing attention. The present work introduces a novel, mass conservative scenario tree reduction in combination with a detailed hindcasting and closed-loop control experiments for a multi-purpose hydropower reservoir in a tropical region in Brazil. The case study is the hydropower project Tres Marias, which is operated with two main objectives: (i) hydroelectricity generation and (ii) flood control downstream. In the experiments, precipitation forecasts based on observed data, deterministic and probabilistic forecasts are used to generate streamflow forecasts in a hydrological model over a period of 2 years. Results for a perfect forecast show the potential benefit of the online optimization and indicate a desired forecast lead time of 30 days. In comparison, the use of actual forecasts of up to 15 days shows the practical benefit of operational forecasts, where stochastic optimization (15 days lead time) outperforms the deterministic version (10 days lead time) significantly. The range of the energy production rate between the different approaches is relatively small, between 78% and 80%, suggesting that the use of stochastic optimization combined with ensemble forecasts leads to a significantly higher level of flood protection without compromising the energy production.

Is strongyloidiasis endemic in Spain?

Is strongyloidiasis endemic in Spain?

Effects of light intensity modification by reflective aluminized screenhouse on sweet pepper growth and yield

Sweet pepper is one of the ten most consumed vegetables in world. Although it develops better under protected environment, the cultivation in tropical countries is practiced in open field due greenhouse structure higher costs. Unfortunately, such practice has compromised the crop to reach either best yield or fruit quality. Since production and cost are the most important criteria for agricultural production, we aimed to evaluate reflective aluminized polypropylene shading net influence on sweet pepper (Capsicum annuum L.) growth and production as intermediary alternative for low/middle income producers from Brazilian tropical regions. Sweet pepper Magali R hybrid was cultivated in two environments: FC - field conditions (control) and RS - reflective shading net with 40% shading rate. RS caused reductions in incident solar radiation (SR) and photosynthetically active radiation (PAR) on the amount of 46.3% and 48.3%, respectively. There were no significant changes in temperature and relative humidity recorded for the two environments. In addition, RS allowed best use efficiency of photosynthetically active radiation since it promoted higher values of plant height, leaf number and area index than those reached on FC on the amount of 29%, 22% and 80 %, respectively. Similarly, plants grown under RS showed higher yield and marketable fruits and promoted less loses by sunscald.

Ultrastructural, morphological, and molecular characterization of Colaconema infestans (Colaconematales, Rhodophyta) and its host Kappaphycus alvarezii (Gigartinales, Rhodophyta) cultivated in the Brazilian tropical region

Endophytic and epiphytic infections have caused serious problems for Kappaphycus farmers, such as reduction in biomass production and decrease in the yield and quality of carrageenan. During environmental monitoring from January 2011 to December 2012, along Pitimbu Beach, Paraiba State, northeastern Brazil, drifting thalli of Kappaphycus alvarezii (Gigartinales, Rhodophyta) were detected with red spots, apparently caused by epiphytic/endophytic infections. Therefore, drifting thalli of K. alvarezii farmed along the northeastern Brazilian coast were cultured in the laboratory and submitted to molecular and morphological analyses to identify and characterize the causative agent and its effects on the cellular structure and ultrastructure of the host alga K. alvarezii that was found to be infected by the endophyte Colaconema infestans (Colaconematales) identified through morphological and rbcL molecular evidence. Infected thalli of K. alvarezii were processed and analyzed through light, transmission electron, and scanning electron microscopy. Alterations were observed in morphology and cellular organization, including structural changes of chloroplasts and decrease in floridean starch grains, along with increased cell wall thickness. Therefore, while no outbreak has been reported, the discovery of C. infestans infection in drifting thallus of K. alvarezii suggests a potential threat to its cultivation that should be monitored.

Sanitary analysis, transmission and pathogenicity of fungi associated with forage plant seeds in tropical regions of Brazil

Brazil is a major producer and exporter of beef in the world, 90% of the production is made in pasture and 85% of cultivated pastures in the country are Brachiaria sp. With a growing livestock industry in the recent years, several forage plant diseases became significant importance for causing losses in pasture productivity and quality. This study aims at quantifying the species of fungi associated with seeds and their frequency in forage plants from tropical regions of Brazil. Assays were performed considering: incidence, pathogenicity and seed-seedling transmission of fungi associated with seeds. Therefore, 28 lots of forage species seeds produced in the harvest of 2010-2011 were used. Fourteen genera of fungi associated with seeds were found, among which Bipolaris sp., Phoma sp., and Curvularia sp. had pathogenic potential. It was possible to note that Bipolaris sp., is prejudicial to forage seedlings of Brachiaria, Panicum and Crotalaria. Bipolaris sp. and Curvularia sp. have an average of seed-seedling transmission of 100% and 90%, respectively.

Genetic Analysis of Growth Traits in Polled Nellore Cattle Raised on Pasture in Tropical Region Using Bayesian Approaches

Components of (co)variance and genetic parameters were estimated for adjusted weights at ages 120 (W120), 240 (W240), 365 (W365) and 450 (W450) days of Polled Nellore cattle raised on pasture and born between 1987 and 2010. Analyses were performed using an animal model, considering fixed effects: herd-year-season of birth and calf sex as contemporary groups and the age of cow as a covariate. Gibbs Samplers were used to estimate (co)variance components, genetic parameters and additive genetic effects, which accounted for great proportion of total variation in these traits. High direct heritability estimates for the growth traits were revealed and presented mean 0.43, 0.61, 0.72 and 0.67 for W120, W240, W365 and W450, respectively. Maternal heritabilities were 0.07 and 0.08 for W120 and W240, respectively. Direct additive genetic correlations between the weight at 120, 240, 365 and 450 days old were strong and positive. These estimates ranged from 0.68 to 0.98. Direct-maternal genetic correlations were negative for W120 and W240. The estimates ranged from −0.31 to −0.54. Estimates of maternal heritability ranged from 0.056 to 0.092 for W120 and from 0.064 to 0.096 for W240. This study showed that genetic progress is possible for the growth traits we studied, which is a novel and favorable indicator for an upcoming and promising Polled Zebu breed in Tropical regions. Maternal effects influenced the performance of weight at 120 and 240 days old. These effects should be taken into account in genetic analyses of growth traits by fitting them as a genetic or a permanent environmental effect, or even both. In general, due to a medium-high estimate of environmental (co)variance components, management and feeding conditions for Polled Nellore raised at pasture in tropical regions of Brazil needs improvement and growth performance can be enhanced.

An AFLP estimation of the outcrossing rate of &lt;i&gt;Spondias tuberosa&lt;/i&gt; (Anacardiaceae), an endemic species to the Brazilian semiarid region

The umbu tree (Spondias tuberosa) is one of the most important endemic species to the Brazilian tropical semiarid region. The umbu tree has edible fruits with a peculiar flavor that are consumed in natura or in a semi-industrialized form, such as jams, candies and juices. The majority of endemic species to Brazilian semiarid region have not been studied or sampled to form germ-plasm collections, which increases the risk of losing genetic variability of the adapted species to xerophytic conditions. The aim of this study was to estimate outcrossing rates in S. tuberosa using a multilocus mixed model in order to guide genetic resources and breeding programs of this species. DNA samples were extracted from 92 progenies of umbu trees, which were distributed among 12 families. These trees were planted by seed in 1991 in Petrolina, PE, Brazil. The experimental design was a randomized block, with a total of 42 progenies sampled in three regions. The experimental units were composed by five plants and five replications. The outcrossing rate was estimated by the multilocus model, which is available in the MLTR software, and was based on 17 polymorphic AFLP bands obtained from AAA_CTG and AAA_CTC primer combinations. The observed heterozygotes ranged from 0.147 to 0.499, with a maximum frequency estimated for the AAA_CTC 10 amplicon. The multilocus outcrossing estimation (t(m)) was 0.804 +/- 0.072, while the single-locus (t(s)) was 0.841 +/- 0.079, which suggests that S. tuberosa is predominantly an outcrossing species. The difference between t(m) and t(s) was -0.037 +/- 0.029, which indicates that biparental inbreeding was nearly absent. The mean inbreeding coefficient or fixation index (F) among maternal plants was--0.103 +/- 0.045, and the expected F was 0.108, which indicates that there was no excess of heterozygotes in the maternal population. The outcrossing estimates obtained in the present study indicate that S. tuberosa is an open-pollinated species. Biometrical models applied to this species should therefore take into account the deviation from random outcrossing to estimate genetic parameters and the constitution of broad germplasm samples to preserve the genetic variability of the species. Outcrossing rates based on AFLP and the mixed-mating model should be applied to other studies of plant species in the Brazilian semiarid region.

Soil organic carbon fraction losses upon continuous plow-based tillage and its restoration by diverse biomass-C inputs under no-till in sub-tropical and tropical regions of Brazil

The conversion of native vegetation (NV) into agricultural land by clearing and tillage disrupts the soil structure, and depletes soil organic carbon (SOC) pool. The data on changes in SOC pools are needed to enhance scientific knowledge regarding the effects of land use and no-till (NT) systems on soil fertility, agronomic productivity, and soil C sink capacity. Thus, the objective of this study was to quantify changes in SOC fractions due to conversion of NV to agricultural land, and to assess the rate of recovery of SOC fractions and the resilience index of NT cropping systems under sub-tropical (Ponta Grossa/PR — PG) and tropical (Lucas do Rio Verde/MT — LRV) regions of Brazil. The conversion from CT to NT was 29 and 8years at the PG and LRV sites, respectively. Five different fractions of SOC pools were extracted by chemical methods (i.e., C in the polysaccharides — CTPS, hot-water extractable C — HWEOC, chemically-stabilized organic C — CSOC), and physical fractionation (i.e., particulate organic C — POC, and mineral-associated organic C — MAOC). Land use change primarily altered the labile (HWEOC, TPS, and POC) and also some of the stable (MAOC) pools at both sites. The CSOC pool was almost constant throughout the soil profile and represented, across land uses, 7.2gCkg−1 at the PG and 3.1gCkg−1 at the LRV sites. At the PG site, the HWEOC and CTPS concentrations in the 0–5cm depth decreased by 56% (1.21gkg−1) and 45% (7.21gkg−1) in CT soil, respectively. At the LRV site, concentrations of HWEOC and CTPS in the 0–5cm depth decreased by 50% (0.4gkg−1) and 42% (4.8gkg−1), respectively. In contrast, concentrations of HWEOC and CTPS fractions in soil under NT in the 0–20cm depth were closer than those under NV, and exhibited a distinct gradient from surface to sub-soil layers. The adoption of CT reduced POC by 46% (4.7Mgha−1), and MAOC by 21% (15.1MgCha−1) in the 0–20cm depth at the PG site. Using CT for 23years at the LRV site, decreased SOC fractions in the 0–20cm depth at the rate of 0.25 and 0.34MgCha−1yr−1 for POC and MAOC, respectively. In contrast, adoption of intensive NT systems in tropical agro-ecoregions increased POC at the rate of 0.23 to 0.36MgCha−1yr−1, and MAOC by 0.52 and 0.70MgCha−1yr−1. An important effect to be emphasized is the possibility of recovering, at least partially, the SOC fractions by adopting high biomass-C inputs under NT management, and despite the fact that the experimental duration at the LRV site was only eight years. With a high and diversified input of biomass-C in intensive NT systems, higher resilience index was observed for CTPS, HWEOC, and MAOC. The variation in SOC among CT and NT systems was mainly attributed to the MAOC fraction, indicating that a significant proportion of that fraction is relatively labile, and that spatial inaccessibility of SOC plays a significant role in the restoration of SOC.

Molecular identification of the exotic lineage of &lt;i&gt;Kappaphycus alvarezii&lt;/i&gt; (Rhodophyta, Solieriaceae) cultivated in the tropical region of Brazil

Kappa carrageenan is an important phycocolloid extracted from the red seaweed Kappaphycus alvarezii. This species has been introduced into several regions, most recently in Brazil. The remote invasive potential of this seaweed in both south and southeast waters of Brazil (subtropical regions) has been established, but introduction in the northeastern tropical area is contested due to the absence of biological information. An unknown exotic lineage of K. alvarezii has been illegally introduced and cultivated in an area characterized by the presence of coral reefs in Paraíba, the northeastern Brazilian coast, since the beginning of the last decade. This work focuses on the molecular identification of these samples in comparison with sequences of other strains of K. alvarezii and congeners available in Genbank. Maximum likelihood (ML) and Bayesian inference (BI) analyses showed strong similarities between K. alvarezii cultivated in the tropical waters in Brazil and those lineages cultivated in Hawaii, Venezuela, Malaysia and Tanzania that have never shown invasive behavior. However, more detailed investigations and use of environmental monitoring are recommended before commercial cultivation of this species can be authorized in tropical region of Brazil.

Phenological studies in populations of Hypnea musciformis (Rhodophyta: Gigartinales) in a tropical region of Brazil

(Phenological studies in populations of Hypnea musciformis (Rhodophyta: Gigartinales) in a tropical region of Brazil). The species H. musciformis is one of the main natural sources of k-carrageenan, a polysaccharide widely used in the cosmetics, textiles and food industries. There are few phenological studies with natural populations of this species, especially in the northeast of Brazil. This study aims to contribute to the knowledge of the biology and ecology of H. musciformis in a tropical region of Brazil by analyzing its reproductive and phenological aspects. Two epiphytic populations of this species were analyzed on the beaches of Stella Maris (Salvador) and Itacimirim (Camacari), located in Bahia, Brazil. A total of eight sampling were made during the dry and rainy seasons from 2007 to 2009. The samples were obtained using transects (20 m) and square (0.04 m2) in three regions based on different reef hydrodynamics: tidal pool, protected reef region and front reef region. For statistical analysis, Fisher’s exact test was used with confidence level of significance for all tests set at 95 % (P = 0.05). No male specimens were observed and carposporophytes were rare during the study. The occurrence of infertile specimens was low, especially at Stella Maris. The tetrasporophytic phase was dominant in all sampled sites. The seasonality analysis showed higher percentage of samples in tetrasporophytic phase in Stella Maris, during the dry season, while in Itacimirim there were no differences between dry and rainy seasons. The phenology of algae could have been influenced by the interaction of abiotic and biotic factors, modifying their reproductive behavior according to environmental changes.

Aggregate C depletion by plowing and its restoration by diverse biomass-C inputs under no-till in sub-tropical and tropical regions of Brazil

Encapsulation of soil organic carbon (SOC) within aggregates is one of the principal mechanisms for long-term C sequestration, macroaggregate formation and stabilization. Our objectives were to quantify the changes in aggregate size distribution, aggregate-C concentrations and stocks upon conversion of native vegetation (NV) to conventional plow-based tillage (CT), and to assess the rate of aggregation and SOC recovery with no-till (NT) under diverse biomass-C inputs. The study was conducted at both sub-tropical (Ponta Grossa – PG, State of Paraná) and tropical (Lucas do Rio Verde – LRV, State of Mato Grosso) sites in Brazil. The SOC content under NV was used as a baseline to evaluate the depletion rate under CT and the restoration rate under NT. A specific emphasis was given to the largest macroaggregate size class (8–19mm) because of its importance to protecting the recently deposited labile SOC. A discriminant analysis of principal components (DAPC) indicated that NV soil is modified by conversion to an arable land use and that, mechanical tillage, biomass input, and their interactions drastically influence the distribution of aggregate-size classes, aggregation indices, and SOC distribution within aggregates. At both sites, soil aggregation indices were positively impacted by NT and associated with SOC concentration in the labile fractions (e.g., total polysaccharides (TPS), hot water extractable organic C (HWEOC), particulate organic C (POC)). At the PG site, the 8–19mm aggregate size fraction was significantly affected by land use and tillage treatments and represented 54%, 43%, and 72%, under NV, CT, and NT in 0–20cm depth, respectively. Furthermore, the 8–19mm size fraction stored 55%, 45%, and 71% of the total SOC stock under NV (53.8MgCha−1), CT (28.5MgCha−1) and NT (51.2MgCha−1), respectively. At the LRV site, the 8–19mm aggregate size fraction decreased from 50% under Cerrado NV to 35% under CT, and ranged from 33% to 51% under diverse biomass-C input under NT in 0–20cm depth. The 8–19mm size fraction stored 52%, 37%, and 41% of the total SOC stock across all aggregate sizes under NV (25.4MgCha−1), CT (11.7MgCha−1), and NT (9.9–18.1MgCha−1), respectively. The difference in SOC stock among land uses is largely attributed to storage in the 8–19mm aggregate size class, indicating that NT cropping systems rebuilt the largest macroaggregates, which are crucial for stabilization of SOC.

Formation of DNA Strand Breaks in Peripheral Lymphocytes of Rats After Exposure to Natural Sunlight

ObjectiveThis paper aims to evaluate the genotoxicity in peripheral blood lymphocytes of rats after exposure to sunlight at different time points of day in a tropical region of Brazil (5°S, 42°W). Materials and MethodsThirty Wistar-Hannover rats, three months old, were randomly divided into three groups of 10 animals each: Group I [control, without exposure to ultraviolet (UV) radiation], Group II (exposed to sunlight during 08:00 a.m. to 10:00 a.m.), and Group III (exposed to sunlight during 10:00 a.m. to 12:00 a.m.). After a week of exposure, peripheral blood samples were taken from the tail of these animals to prepare smears on two slides per animal. In 24 h after exposure to sunlight in Group III, a new collection was obtained to observe the repair activity. The alkaline comet assay was used in this study to evaluate the genotoxic activity of sunlight (P<0.05). ResultsThere was no statistical difference between Group I and II (P=0.672). On the other hand, the exposure to sunlight in Group III showed genotoxic action in comparison to the other groups (P<0.0001). Also, there was no significant repair in Group III R (P=0.407). ConclusionThis study has shown a genotoxic potential of sunlight (UVA-B) in lymphocytes of mammals from 10:00 a.m. to 12:00 a.m., due to a higher intensity of UV in this tropical region.

The Prevalence of Low Bone Mineral Density in Brazilian Patients With Systemic Lupus Erythematosus and Its Relationship With the Disease Damage Index and Other Associated Factors

The aim of this study was to examine the prevalence of osteoporosis, osteopenia, and bone mineral density (BMD) less than the expected range based on age in patients with systemic lupus erythematosus (SLE) in a tropical region of Brazil and the relationship between reduced BMD and several associated factors, especially the SLE disease damage index (SDI). We scored 159 patients with creatinine clearance of 60mL/min or more for SDI, which was modified by excluding the osteoporosis item. For postmenopausal women and men older than 50yr, T-scores identified osteopenia (<−1.0 and >−2.5) and osteoporosis (≤−2.5). For all patients, a Z-score of −2.0 or less identified BMD less than the expected range for age. Other variables that influence BMD were studied. The prevalence of osteoporosis, osteopenia, and BMD less than the expected range for age was 28%, 54%, and 29.6%, respectively. The Z-scores were significantly lower in patients with a modified SDI≥1 (mean±standard deviation [SD]=−1.45±1.18) compared with patients with a modified SDI=0 (mean±SD=−0.94±1.01; p=0.01). The lowest Z-score had a significant association with postmenopausal status (p=0.038) and significant correlations with the duration of glucocorticoid (GC) usage (p=0.033, r=−0.17), the cumulative amount of GC (p=0.000, r=−0.28), and parathyroid hormone levels (p=0.003, r=−0.24). A multiple linear regression revealed that the modified SDI (p=0.003) and the cumulative amount of GC (p=0.006) had significant independent associations with the lowest Z-score. In conclusion, a BMD less than the expected range for age occurs frequently in Brazilian patients with SLE independent of the renal failure. The patients with greater SDIs had lower Z-scores, which suggests a direct association between chronic inflammation from disease and a reduced BMD.

Inferring the impact of environmental conditionings over natural gamma-radiation fluxes in a Brazilian tropical site

Abstract Natural gamma-radiation flux density at Earth’s surface is modulated by soil water retention capacity and the rainout/washout of short-lived radon progenies as major parameters. In this work, 11-year absorbed dose data from 36 TLD environmental stations, installed over different geological domains, allowed a better understanding of temporal and spatial variability of natural gamma-radiation, at a tropical region of Brazil. The results show conspicuous one-year cyclicity with increases during the winter-fall (dry season), varying from 3.9 to 14.1% compared to summer (wet season). TLD stations installed at beach sand terrains presented elevated coefficient of variation compared to results at soils and rocky terrains. This difference was attributed tentatively to changes in naturally occurring radionuclides activity concentrations in accordance with coastal sedimentary dynamics. Additionally, long-term TLD databases, selected from main geological domains, allowed the modeling of regional absorbed dose rates.

Development and survival of the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Yponomeutidae) as a function of temperature: effect on the number of generations in tropical and subtropical regions.

The diamondback moth, Plutella xylostella (L.), is the most important pest of brassicaceous crops worldwide. Since temperature is the major abiotic factor influencing insect development and thermal requirements may vary among insect populations, it is important to know the effect of temperature on development and survival of a subtropical strain of P. xylostella. Development and survival of the diamondback moth was evaluated under seven constant temperatures ranging from 10°C to 35°C. Development was completed between 10°C and 32.5°C, but at 35°C all individuals died in the larval stage. Data were fitted to one linear and five nonlinear models. Considering as criteria the goodness of fit and the ability to estimate parameters of biological significance, the models Briere-1 and Briere-2 were the most adequate to describe the relationship between temperature and development of P. xylostella. The linear model demonstrated that P. xylostella required 312.5 degree-days above a lower threshold of 6.3°C to complete development. The degree-day model showed that the number of diamondback moth generations in the tropical region of Brazil is nearly twice the number in the subtropical region of the country. This result explains, at least in part, the higher population levels of this species in the tropical region of Brazil, and also demonstrates that P. xylostella is tolerant to a wide range of temperatures (6.1-32.5°C). Therefore, temperature cannot be considered a limiting factor for the occurrence of diamondback moth throughout the year in most regions of Brazil.

Identification of microsatellite loci in Pinus tecunumanii

Background Pinus tecunumanii has displayed good performance in tropical regions of Brazil and showed high potential for commercial exploitation. Embrapa Forestry and its partners own many of the species seed production areas. In spite of its importance, the majority of P. tecunumanii germplasm collections remain still genetically uncharacterized. Thus identifying genetic markers is an important tool to genetically characterize these collections.We describe the initial steps to develop microsatellites for Pinus tecunumanii by enriched library construction with the ultimate goal of characterizing accessions of the germplasm collections of EMBRAPA.

Land-cover classification in a moist tropical region of Brazil with Landsat Thematic Mapper imagery

This research aims to improve land-cover classification accuracy in a moist tropical region in Brazil by examining the use of different remote-sensing-derived variables and classification algorithms. Different scenarios based on Landsat Thematic Mapper (TM) spectral data and derived vegetation indices and textural images and different classification algorithms, maximum likelihood classification (MLC), artificial neural network (ANN), classification tree analysis (CTA) and object-based classification (OBC), were explored. The results indicate that a combination of vegetation indices as extra bands into Landsat TM multi-spectral bands did not improve the overall classification performance, but the combination of textural images was valuable for improving vegetation classification accuracy. In particular, the combination of both vegetation indices and textural images into TM multi-spectral bands improved the overall classification accuracy (OCA) by 5.6% and the overall kappa coefficient (OKC) by 6.25%. Comparison of the different classification algorithms indicated that CTA and ANN have poor classification performance in this research, but OBC improved primary forest and pasture classification accuracies. This research indicates that use of textural images or use of OBC are especially valuable for improving the vegetation classes such as upland and liana forest classes that have complex stand structures and large patch sizes.

Plasma bubble zonal drift characteristics observed by airglow images over Brazilian tropical region

Using airglow images observed at São João do Cariri (7.4ºS, 36.5ºW; dip angle: -11ºS) from September 2000 to April 2007, plasma bubblezonal drifts for ninety-seven geomagnetically quiet nights (Dst index higher than -30 nT) were calculated. The plasma bubble eastward averaged drifts presented an increase from 18:00 to 22:00 local time (LT), and followed by a deceleration. The plasma bubbles observed during high solar activity were faster after 22:00 LT. Eastward drifts observed during the summer, after 21:00 LT, were higher than drifts observed during the equinox months. Few nights had plasma bubble eastward drifts higher than 100 m/s and almost all bubbles disappeared after 02:00 LT. Averaged zonal drifts observed between -9.5 and -5.5ºS were almost constant, primarily,around 23:00 LT.