N-acetylcysteine absorption and its potential dual effect improve fitness and fruit yield in Xylella fastidiosa infected plants.

BACKGROUND: Xylella fastidiosa is a multi-host bacterium that can be detected in hundreds of plant species including several crops. Diseases caused by X. fastidiosa are considered a threat to global food production. The primary method for managing diseases caused by X. fastidiosa involves using insecticides to control the vector. Hence, it is necessary to adopt new and sustainable disease management technologies to control not only the insect but also the bacteria and plant health. We demonstrated that N-acetylcysteine (NAC), a low-cost cysteine analogue, is a sustainable molecule that can be used in agriculture to decrease the damage caused by X. fastidiosa and improve plant health. RESULTS: Using 15N-NAC we proved that this analogue was absorbed by the roots and transported to different parts of the plant. Inside the plant, NAC reduced the bacterial population by 60-fold and the number of xylem vessels blocked by bacterial biofilms. This reflected in a recovery of 0.28-fold of the daily sap flow compared to health plants. In addition, NAC-treated citrus variegated chlorosis (CVC) plants decreased the oxidative stress by improving the activity of detoxifying enzymes. Moreover, the use of NAC in field conditions positively contributed to the increase in fruit yield of CVC-diseased plants. CONCLUSION: Our research not only advances the understanding of NAC absorption in plants, but also indicates its dual effect as an antimicrobial and antioxidant molecule. This, in turn, negatively affects bacterial survival while improving plant health by decreasing oxidative stress. Overall, the positive field-based evidence supports the viability of NAC as a sustainable agricultural application. © 2024 Society of Chemical Industry.

Is central venous catheter in haemodialysis still the main factor of mortality after hospitalization?

BACKGROUND: Haemodialysis is the most frequently prescribed Renal Replacement Therapy modality worldwide. However, patients undergoing this therapy have an unpredictable evolution related to vascular access. OBJECTIVE: To determine the factors associated with the mortality and hospitalization rate in haemodialysis patients at a third-level care Centre in the Dominican Republic. METHODS: This was an observational and prospective study involving a cohort of 192 haemodialysis patients. The patient selection was non-probabilistic for convenience, and a direct source questionnaire was applied. RESULTS: Of the 192 patients in the cohort, 103 (53.6%) were hospitalized and evaluated. The most frequent cause of hospitalization was catheter-related bloodstream infections (53.4%). Almost one-third (28.2%) of the hospitalized patients died, mostly due to infections (12.6%). Of those who died 29 patients (90%) had a Central venous catheter (CVC) with a non-tunnelled catheter (NTCVC) (65.5%); having an NTC CVC makes a patient 85.5 times more likely to be hospitalized than patients with arteriovenous fistulas. CONCLUSION: Vascular access plays a predominant role in the hospitalization and mortality rates in haemodialysis. Patients with an arteriovenous fistula obtained significantly better outcomes than those with central venous catheters.

Inoculum reduction and vector control on the temporal progress of citrus variegated chlorosis incidence.

BACKGROUND: Citrus variegated chlorosis (CVC) is an important citrus disease caused by the sharpshooter-transmitted bacterium Xylella fastidiosa subsp. pauca. Information about the efficacy of its disease management is bounded to either inoculum reduction or vector control. This study aimed to assess the role of different frequencies of roguing of symptomatic trees combined with different chemical control programs for the sharpshooters on CVC temporal progress. The experimental area was set up in October 2005 and had a 3 × 3 factorial design. Symptomatic tree removal intervals were every 28, 56, and 112 days to May 2012. Vector control treatments were no control, program A (PA), and program B (PB). Contact insecticides were sprayed every 28 (PA) or 14 (PB) days. Trees within both programs were treated with systemic and foliar insecticides to October 2008. After this, systemic insecticides were discontinued and only foliar treatments were applied. The number of diseased trees and the sharpshooter population were assessed to April 2015. RESULTS: Detection of the first symptomatic trees was similar for all treatments and occurred, on average, in month 50 after planting. Sharpshooter population and cumulative disease incidence were similar for all roguing intervals and between vector control programs, differing in plots with no control. We observed a reduction over 85% in disease incidence for both PA and PB compared with no control. CONCLUSION: These results support systematic control of sharpshooters as an efficient strategy for reducing CVC progress. © 2021 Society of Chemical Industry.

Huanglongbing and Citrus Variegated Chlorosis Integrated Management Based on Favorable Periods for Vector Population Increase and Symptom Expression.

Huanglongbing (HLB, associated with Candidatus Liberibacter asiaticus and transmitted by the Asian citrus psyllid Diaphorina citri) and citrus variegated chlorosis (CVC, caused by Xylella fastidiosa subsp. pauca and transmitted by sharpshooter species) have been managed by vector control and removal of symptomatic trees. Although vectors and new symptomatic trees can be detected year round, peaks of vector populations are higher in spring and summer, and the most symptomatic trees are found in autumn and winter. This work aimed to compare the management of both diseases during these favorable periods. The experiment was conducted during 5 years in a commercial orchard and had a three-by-two factorial design. The factor "vector control" had three levels: monthly vector control year round (VCYR), monthly vector control in spring and summer (VCSS), and vector control when a threshold level of 10% occupancy was detected (VCOT). The factor "inoculum removal" had two levels: monthly eradication year round (TEYR) and monthly eradication in autumn and winter (TEAW). Host flush, both HLB and CVC vector populations, and the number of symptomatic citrus plants were visually assessed. The level of vectors over the seasons, as measured using the average area under the curve (AUC), was similar for all treatments with the exception of psyllid abundance, which was approximately 4.5 times higher for VCSS than for other treatments. For both diseases, no difference in the average AUC of disease progress and disease final incidence was observed. VCOT or adjusted VCSS associated with TEAW could be integrated for sustainable citrus production.

Citrus reticulata CrRAP2.2 Transcriptional Factor Shares Similar Functions to the Arabidopsis Homolog and Increases Resistance to Xylella fastidiosa.

Xylella fastidiosa is a worldwide multihost pathogen that causes diseases in different crops. It is considered a new global threat and substantial efforts have been made in order to identify sources of resistance. Indeed, many genes have been associated with resistance to X. fastidiosa, but without functional validation. Here, we describe a C. reticulata gene homologous to the transcriptional factor RAP2.2 from Arabidopsis thaliana that increases resistance to citrus variegated chlorosis (CVC). This gene was previously detected in C. reticulata challenged with X. fastidiosa. Bioinformatics analysis together with subcellular localization and auto-activation assays indicated that RAP2.2 from C. reticulata (CrRAP2.2) is a transcriptional factor orthologous to AtRAP2.2. Thus, we used A. thaliana as a model host to evaluate the functional role of CrRAP2.2 in X. fastidiosa resistance. The inoculation of X. fastidiosa in the A. thaliana rap2.2 mutant resulted in a larger bacterial population, which was complemented by CrRAP2.2. In addition, symptoms of anthocyanin accumulation were higher in the mutant, whose phenotype was restored by CrRAP2.2, indicating that they have conserved functions in plant defense response. We therefore transformed C. sinensis with CrRAP2.2 and verified a positive correlation between CVC resistance and gene expression in transgenic lines. This is the first study using A. thaliana as model host that characterizes the function of a gene related to X. fastidiosa defense response and its application in genetic engineering to obtain citrus resistance to CVC.

Scion Substitution: A New Strategy to Control Citrus Variegated Chlorosis Disease.

Citrus variegated chlorosis (CVC) disease, caused by the xylem-limited and insect-transmitted bacterium Xylella fastidiosa, has caused severe losses in orange production in Brazil. Disease control requires insecticide applications, tree removal, and pruning of symptomatic branches. Pruning success has been erratic, especially in areas of high disease incidence. In this work, in planta X. fastidiosa distribution and the effectiveness of severe pruning procedures for curing diseased adult trees were investigated. Most sampled upper parts of the trees contained X. fastidiosa, but at higher frequencies in symptomatic branches. Removal of all main branches (decapitation) was not effective and revealed a 20 to 30% incidence of latent infections. Trunk decapitation resulted in a higher number of healthy scions but killed 10 to 30% of the remaining trunks. Removal of all scion and grafting the newly sprouted shoots of 'Rangpur' lime (Citrus limonia Osbeck) or 'Cleopatra' (Citrus reshni Hort. ex Tan.) rootstocks with healthy buds allowed production of fast-growing and productive new scions that remained free from CVC for at least 2 years in four locations. With this method, highly affected trees do not need to be fully removed and the costs involved in this practice and in young tree acquisition and plantings are circumvented; therefore, it is a feasible option for less technically inclined small growers in Brazil.

No difference in acute effects of supplemental v. dietary calcium on blood pressure and microvascular function in obese women challenged with a high-fat meal: a cross-over randomised study.

Recent studies suggest that supplemental Ca (SC) increases the risk of cardiovascular events, whereas dietary Ca (DC) decreases the risk of cardiovascular events. Although frequently consumed with meals, it remains unclear whether Ca can mitigate or aggravate the deleterious effects of a high-fat meal on cardiovascular risk factors. This study aimed to evaluate the effects of SC or DC on blood pressure (BP) and microvascular function (MVF) in the postprandial period in obese women challenged with a high-fat meal. In this cross-over controlled trial, sixteen obese women aged 20-50 years were randomly assigned to receive three test meals (2908 kJ (695 kcal); 48 % fat): high DC (HDCM; 547 mg DC), high SC (HSCM; 500 mg SC-calcium carbonate) and low Ca (LCM; 42 mg DC). BP was continuously evaluated from 15 min before to 120 min after meals by digital photoplethysmography. Before and 120 min after meals, participants underwent evaluation of serum Ca and microvascular flow after postocclusive reactive hyperaemia (PORH) by laser speckle contrast imaging. Ionised serum Ca rose significantly only after HSCM. Systolic BP increased after the three meals, whereas diastolic BP increased after LCM and HDCM. Hyperaemia peak, hyperaemia amplitude and AUC evaluated after PORH decreased with LCM. After HDCM, there was a reduction in hyperaemia peak and hyperaemia amplitude, whereas HSCM decreased only hyperaemia peak. However, comparative analyses of the effects of three test meals on serum Ca, BP and MVF revealed no significant meal×time interaction. This study suggests that in obese women SC and DC do not interfere with the effects of a high-fat meal on BP and MVF.

Risk factors and biofilm detection on central venous catheters of patients attended at tertiary hospital.

AIM: To determinate the significance of risk factors with the presence of biofilm on catheters of patients attended at tertiary hospital cares. MATERIAL AND METHODS: A total of 126 patients were included, data collection by observing the handling of the CVC, clinical history and microbiological isolation methods of CVCs tips (Roll-plate, sonication and scanning electron microscopy) were evaluated. RESULTS: Certain factors, such as the lack of proper hand washing, the use of primary barriers and preparing medications in the same hospital service, showed an important relationship between biofilm formation in CVCs. The sonication method presented that most of the samples had isolation of multispecies 29 samples (64%); in contrast with the roll-plate method, just one sample (3%) was isolated. CONCLUSIONS: The importance of the strict aseptic techniques of insertion and of the handlings of CVC was highlighted, the failure of both techniques was related to the biofilm formation and was evidenced using the scanning electron microscopy. Since this tool is not available in most hospitals, we present the correlation of those evidences with other standard microbiological methods and risk factors, which are necessary for the sensible detection of the different steps of the biofilm formation on CVC and their correct interpretation with clinical evidences.

Routine surveillance ultrasound for the management of central venous catheters in neonates.

OBJECTIVES: To evaluate the frequency of central venous catheter (CVC)-related thrombi detected by routine surveillance ultrasound, and to assess whether positive findings had an impact on management or outcomes. STUDY DESIGN: All neonates in a tertiary neonatal intensive care unit who had a CVC inserted for >14 days underwent routine surveillance ultrasound biweekly between January 2003 and December 2009. Data were reviewed retrospectively. RESULTS: Although all neonates were asymptomatic at time of surveillance ultrasound, 645 of the total 1333 CVCs inserted in 1012 neonates underwent surveillance ultrasound, and thrombi were detected in 69 (10.7%). The CVCs with thrombi were more likely to be removed for nonelective reasons compared with CVCs without thrombi (59% vs 38%; P = .001; OR, 2.4, 95% CI 1.4-3.9). A total of 955 surveillance ultrasounds were performed to detect and monitor 69 CVCs with thrombi. The majority of thrombi were nonocclusive and nonprogressive. A change in management occurred in 8 cases of CVC-related thrombi (12%), or 1% of all screened cases. An average of 14 ultrasounds were required to detect and monitor 1 CVC with thrombus, at a cost of $951 per CVC with thrombus and $8106 per case of CVC-related thrombi with a change in treatment. CONCLUSION: Asymptomatic thrombi were detected in a significant proportion of CVCs by routine surveillance ultrasound. There were significant costs, but infrequent changes to patient management.

Hospital-associated venous thromboembolism in children: incidence and clinical characteristics.

OBJECTIVE: To determine incidence and clinical characteristics of hospital-associated venous thromboembolism (VTE) in pediatric patients. STUDY DESIGN: A retrospective analysis of patients with hospital-associated VTE at the Johns Hopkins Hospital from 1994 to 2009 was performed. Clinical characteristics of patients aged 21 years and younger who developed VTE symptoms after 2 days of hospitalization or <90 days after hospital discharge were examined. International Classification of Diseases, Ninth Revision codes were used to categorize patients with complex chronic medical conditions and trauma. RESULTS: There were 270 episodes of hospital-associated VTE in 90,485 admissions (rate 30 per 10,000 admissions). Young adults (18-21 years) and adolescents (14-17 years) had significantly increased rates of VTE compared with children (2-9 years) (incidence rate ratio [IRR] 7.7, 95% CI 5.1-12.0; IRR 4.3, 95% CI 2.7-6.8, respectively). A central venous catheter (CVC) was present in 50% of patients, and a surgical procedure was performed in 45% of patients before VTE diagnosis. For patients without a CVC, trauma was the most common admitting diagnosis. CVC-related VTE was diagnosed most frequently in infants (<1 year old) and in patients with malignancy. Renal and cardiac diseases were associated with the highest rates of VTE (51 and 48 per 10,000, respectively). Rates were significantly higher among those with ≥ 4 medical conditions compared with those with 1 medical condition (IRR 4.0, 95% CI 1.4-8.9). CONCLUSION: Older age and multiple medical conditions were associated with increased rates of hospital-associated VTE. These data can contribute to the design of future clinical trials to prevent hospital-associated VTE in high-risk children.

Port-a-cath-related thrombosis and postthrombotic syndrome in pediatric oncology patients.

OBJECTIVE: To investigate Port-A-Cath (PAC)-related thrombosis and postthrombotic syndrome (PTS) in children with cancer. STUDY DESIGN: The study population was a consecutive cohort of children diagnosed with cancer and a PAC implanted at diagnosis. Children were evaluated for the presence of PAC-related thrombosis by magnetic resonance venography and the presence of congenital prothrombotic risk factors and PTS. RESULTS: A total of 114 children (median age, 6.04 years) were included. Of these children, 48 (42%) were treated for solid tumors and 66 (58%) were treated for hematopoietic tumors, including 38 for acute lymphoblastic leukemia. At the time of magnetic resonance venography, 42 children (37%) had the PAC still in place, and 72 (63%) had the PAC removed. Overall, PACs were in place for a total of 324.92 PAC-years. PAC-related thrombosis was detected in 45 children (39.5%) with a current or previous PAC. Of these, 21 (47%) had a solid tumor, 14 (31%) had acute lymphoblastic leukemia, and 10 (22%) had another hematopoietic tumor. Younger age at diagnosis, female sex, duration of PAC use, and left-side PAC placement were independently associated with an increased risk of thrombosis, whereas asparaginase therapy and the presence of inherited prothrombotic risk factors were not. Mild PTS (ie, presence of prominent collateral vessels in the skin) was present in 5.6% of the children. CONCLUSION: PAC-related thrombosis is common in pediatric oncology patients. In some children, thrombotic complications can lead to the development of PTS.

Nutritional deficiency in citrus with symptoms of citrus variegated chlorosis disease / Deficiência nutricional em citros com sintomas da doença da clorose variegada dos citros

It is well known that citrus plants that have been infected by Xylella fastidiosa display nutritional deficiencies, probably caused by production of extracellular polymers by the bacteria that block normal nutrient flow through the xylem. The aim of this work was to study the mineral composition of specific foliar areas in different stages of infection in citrus. Thus, the concentrations of macro and micronutrients in leaves of citrus infected by X. fastidiosa were measured. Samples from four infected citrus orchards in the State of São Paulo, Brazil, were respectively collected from Santa Rita do Passa Quatro, Neves Paulista, Gavião Peixoto and Paraíso counties. The presence of X. fastidiosa in leaves was confirmed by polymerase chain reaction (PCR) using specific PCR primers. To understand the variation in leaf-nutrient content in citrus plants, we used foliar nutrient values from control (non-symptomatic) plants as a reference. Chemometric analysis showed that the deficiency of P and K in symptomatic trees for all orchards and high concentrations of Fe, Mn and Zn were observed in chlorotic areas, although other studies revealed deficiency of zinc in leaves. This is the first report showing that a correlation between chlorotic citrus leaf and higher concentrations of Fe, Mn and Zn are observed when infected and healthy plants were compared.

Já é bem conhecido que cultivares cítricas que foram infectadas pela bactéria Xylella fastidiosa apresentam deficiências nutricionais devido à produção de polímero extracelular por esta bactéria, o qual bloqueia o fluxo normal de nutriente pelo xilema. O objetivo deste trabalho foi o de estudar a composição mineral em áreas foliares específicas em diferentes fases de infecção na planta. Assim, as concentrações de macro e micronutrientes em folhas de citros infectados por X. fastidiosa foram quantificadas. Foram coletadas amostras de quatro pomares cítricos infectados localizados em: Santa Rita do Passa Quatro, Neves Paulista, Gavião Peixoto e Paraíso, no Estado de São Paulo. A presença de X. fastidiosa em folhas foi confirmada através de reação da polimerase em cadeia (PCR) usando iniciadores específicos. Para entender a variação no conteúdo de nutriente foliar em plantas cítricas, utilizou-se de valores de nutrientes foliares de plantas não sintomáticas (controle) como referência. A análise quimiométrica mostrou que a deficiência de P e K em plantas sintomáticas e concentrações altas de Fe, Mn e Zn foram presentes em áreas foliares cloróticas, embora outros estudos mostrem a deficiência de zinco em folhas. Este é o primeiro relato indicando que uma correlação entre folhas cítricas cloróticas e elevadas concentrações de Fe, Mn e Zn foi observada quando plantas infectadas e saudáveis foram comparadas.

Nutritional deficiency in citrus with symptoms of citrus variegated chlorosis disease

It is well known that citrus plants that have been infected by Xylella fastidiosa display nutritional deficiencies, probably caused by production of extracellular polymers by the bacteria that block normal nutrient flow through the xylem. The aim of this work was to study the mineral composition of specific foliar areas in different stages of infection in citrus. Thus, the concentrations of macro and micronutrients in leaves of citrus infected by X. fastidiosa were measured. Samples from four infected citrus orchards in the State of São Paulo, Brazil, were respectively collected from Santa Rita do Passa Quatro, Neves Paulista, Gavião Peixoto and Paraíso counties. The presence of X. fastidiosa in leaves was confirmed by polymerase chain reaction (PCR) using specific PCR primers. To understand the variation in leaf-nutrient content in citrus plants, we used foliar nutrient values from control (non-symptomatic) plants as a reference. Chemometric analysis showed that the deficiency of P and K in symptomatic trees for all orchards and high concentrations of Fe, Mn and Zn were observed in chlorotic areas, although other studies revealed deficiency of zinc in leaves. This is the first report showing that a correlation between chlorotic citrus leaf and higher concentrations of Fe, Mn and Zn are observed when infected and healthy plants were compared.

Já é bem conhecido que cultivares cítricas que foram infectadas pela bactéria Xylella fastidiosa apresentam deficiências nutricionais devido à produção de polímero extracelular por esta bactéria, o qual bloqueia o fluxo normal de nutriente pelo xilema. O objetivo deste trabalho foi o de estudar a composição mineral em áreas foliares específicas em diferentes fases de infecção na planta. Assim, as concentrações de macro e micronutrientes em folhas de citros infectados por X. fastidiosa foram quantificadas. Foram coletadas amostras de quatro pomares cítricos infectados localizados em: Santa Rita do Passa Quatro, Neves Paulista, Gavião Peixoto e Paraíso, no Estado de São Paulo. A presença de X. fastidiosa em folhas foi confirmada através de reação da polimerase em cadeia (PCR) usando iniciadores específicos. Para entender a variação no conteúdo de nutriente foliar em plantas cítricas, utilizou-se de valores de nutrientes foliares de plantas não sintomáticas (controle) como referência. A análise quimiométrica mostrou que a deficiência de P e K em plantas sintomáticas e concentrações altas de Fe, Mn e Zn foram presentes em áreas foliares cloróticas, embora outros estudos mostrem a deficiência de zinco em folhas. Este é o primeiro relato indicando que uma correlação entre folhas cítricas cloróticas e elevadas concentrações de Fe, Mn e Zn foi observada quando plantas infectadas e saudáveis foram comparadas.

Infecciones asociadas a catéteres venosos centrales en la unidad de cuidado intensivo pediátrico / Infections associated with central venous catheters in the pediatric intensive care unit

Las infecciones asociadas a catéteres venosos centrales (CVC), son una fuente importante de morbilidad, mortalidad y de aumento de costos en los pacientes pediátricos hospitalizados. Existen definiciones específicas para las infecciones relacionadas con los CVC en los niños. El tratamiento incluye retirar el catéter e instaurar un antibiótico según la epidemiología del hospital donde se detecta la infección y luego dirigir el tratamiento según los cultivos y antibiograma.

Infections associated to central venous catheters (CVC), are a significant source of morbidity, mortality, and added costs for hospitalized pediatric patients. There are specific definitions for CVC related infections in children. Treatment includes removing the catheter and establishment of an antibiotic according to the epidemiology of the hospital where the infection is detected and subsequently directed treatment depending on the culture and antibiogram results.

Bioassay assessment of metarhizium anisopliae (metchnikoff) sorokin (deuteromycota: hyphomycetes) against Oncometopia facialis (signoret) (hemiptera: cicadellidae)

Citrus Variegated Chlorosis (CVC) is an economically important, destructive disease in Brazil and is caused by Xylella fastidiosa and transmitted by sharpshooter insects. In this study, the efficacy of the fungus Metarhizium anisopliae in controlling the sharpshooter Oncometopia facialis was studied by bioassay conditions. In the bioassay, insects were sprayed with a suspension containing 5 X 10(7) conidia mL-1. Adults captured in the field were treated in groups of 10 in a total of 11 replications per treatment. Significant differences between the natural mortality and the mortality of insects treated with the fungus were observed 6 days after inoculations (P<0.05). These significant differences increased until 10 days after treatment. The fungus caused 87.1 percent mortality, with the LT50 varying from 5 to 6 days. The LC50 was 1.2 X 10(6) conidia mL-1, varying from 7.7 X 10(5) to 2 X 10(6) conidia mL-1. The results showed that the sharpshooter O. facialis was susceptible to the entomopathogenic action of M. anisopliae in controlled condition during bioassay.

A Clorose Variegada dos Citros (CVC) é uma doença economicamente importante e destrutiva no Brasil e é causada pela bactéria Xylella fastidiosa e transmitida por insetos vetores tal como Oncometopia facialis. Nesse estudo, a eficácia do fungo Metarhizium anisopliae em controlar o inseto vetor O. facialis foi estudada em condições de bioensaio. Nesse bioensaio, insetos foram pulverizados com uma suspensão de 5 X 10(7) conídio mL-1. Insetos-adultos capturados no campo foram tratados em grupos de 10, em um total de 11 replicatas por tratamento. Diferenças significativas entre a mortalidade natural e a mortalidade dos insetos tratados com o fungo foram observadas em 6 dias após a inoculação (P<0.05). Estas diferenças significativas aumentaram antes do décimo dia após o tratamento. O fungo causou uma mortalidade de 87,1 por cento, com uma LT50 variando entre 5 e 6 dias. A LC50 foi de 1,2 X 10(6) conídio mL-1, variando de 7,7 X 10(5) a 2 X 10(6) conídio mL-1. Estes resultados mostraram que o vetor O. facialis foi susceptível a ação entomopatogênica de M. anisopliae em condições controladas durante o bioensaio.

Bioassay assessment of metarhizium anisopliae (metchnikoff) sorokin (deuteromycota: hyphomycetes) against Oncometopia facialis (signoret) (hemiptera: cicadellidae).

Citrus Variegated Chlorosis (CVC) is an economically important, destructive disease in Brazil and is caused by Xylella fastidiosa and transmitted by sharpshooter insects. In this study, the efficacy of the fungus Metarhizium anisopliae in controlling the sharpshooter Oncometopia facialis was studied by bioassay conditions. In the bioassay, insects were sprayed with a suspension containing 5 X 10(7) conidia mL(-1). Adults captured in the field were treated in groups of 10 in a total of 11 replications per treatment. Significant differences between the natural mortality and the mortality of insects treated with the fungus were observed 6 days after inoculations (P<0.05). These significant differences increased until 10 days after treatment. The fungus caused 87.1% mortality, with the LT50 varying from 5 to 6 days. The LC50 was 1.2 X 10(6) conidia mL(-1), varying from 7.7 X 10(5) to 2 X 10(6) conidia mL(-1). The results showed that the sharpshooter O. facialis was susceptible to the entomopathogenic action of M. anisopliae in controlled condition during bioassay.

Bioassay assessment of metarhizium anisopliae (metchnikoff) sorokin (deuteromycota: hyphomycetes) against Oncometopia facialis (signoret) (hemiptera: cicadellidae)

Citrus Variegated Chlorosis (CVC) is an economically important, destructive disease in Brazil and is caused by Xylella fastidiosa and transmitted by sharpshooter insects. In this study, the efficacy of the fungus Metarhizium anisopliae in controlling the sharpshooter Oncometopia facialis was studied by bioassay conditions. In the bioassay, insects were sprayed with a suspension containing 5 X 10(7) conidia mL-1. Adults captured in the field were treated in groups of 10 in a total of 11 replications per treatment. Significant differences between the natural mortality and the mortality of insects treated with the fungus were observed 6 days after inoculations (P 0.05). These significant differences increased until 10 days after treatment. The fungus caused 87.1% mortality, with the LT50 varying from 5 to 6 days. The LC50 was 1.2 X 10(6) conidia mL-1, varying from 7.7 X 10(5) to 2 X 10(6) conidia mL-1. The results showed that the sharpshooter O. facialis was susceptible to the entomopathogenic action of M. anisopliae in controlled condition during bioassay.

A Clorose Variegada dos Citros (CVC) é uma doença economicamente importante e destrutiva no Brasil e é causada pela bactéria Xylella fastidiosa e transmitida por insetos vetores tal como Oncometopia facialis. Nesse estudo, a eficácia do fungo Metarhizium anisopliae em controlar o inseto vetor O. facialis foi estudada em condições de bioensaio. Nesse bioensaio, insetos foram pulverizados com uma suspensão de 5 X 10(7) conídio mL-1. Insetos-adultos capturados no campo foram tratados em grupos de 10, em um total de 11 replicatas por tratamento. Diferenças significativas entre a mortalidade natural e a mortalidade dos insetos tratados com o fungo foram observadas em 6 dias após a inoculação (P 0.05). Estas diferenças significativas aumentaram antes do décimo dia após o tratamento. O fungo causou uma mortalidade de 87,1%, com uma LT50 variando entre 5 e 6 dias. A LC50 foi de 1,2 X 10(6) conídio mL-1, variando de 7,7 X 10(5) a 2 X 10(6) conídio mL-1. Estes resultados mostraram que o vetor O. facialis foi susceptível a ação entomopatogênica de M. anisopliae em condições controladas durante o bioensaio.

Analysis of expressed sequence tags from Citrus sinensis L. Osbeck infected with Xylella fastidiosa

In order to understand the genetic responses resulting from physiological changes that occur in plants displaying citrus variegated chlorosis (CVC) symptoms, we adopted a strategy of comparing two EST libraries from sweet orange [Citrus sinensis (L.) Osbeck]. One of them was prepared with plants showing typical CVC symptoms caused by Xylella fastidiosa and the other with non-inoculated plants. We obtained 15,944 ESTs by sequencing the two cDNA libraries. Using an in silico hybridization strategy, 37 genes were found to have significant variation at the transcriptional level. Within this subset, 21 were up-regulated and 16 were down-regulated in plants with CVC. The main functional categories of the down-regulated transcripts in plants with CVC were associated with metabolism, protein modification, energy and transport facilitation. The majority of the up-regulated transcripts were associated with metabolism and defense response. Some transcripts associated with adaptation to stress conditions were up-regulated in plants with CVC and could explain why plants remain alive even under severe water and nutritional stress. Others of the up-regulated transcripts are related to defense response suggesting that sweet orange plants activate their defense machinery. The genes associated with stress response might be expressed as part of a secondary response related to physiological alterations caused by the infection.

Influência das condições hídricas do solo e da temperatura na sobrevivência e alimentação de oncometopia facialis (hemiptera: cicadellidae) em "seedlings" de citros/ / Influence of soil water conditions and temperature on survival and feeding of oncometopia facialis (hemiptera: cicadellidae) on citrus seedlings

RESUMO O comportamento alimentar de cigarrinhas vetoras de Xylella fastidiosa, agente causal da clorose variegada dos citros, pode influenciar sua eficiência de transmissão. Avaliou-se a influência das condições hídricas do solo e da temperatura ambiente na sobrevivência e alimentação do vetor Oncometopia facialis (Hemiptera: Cicadellidae) em "seedlings" de laranjeira doce (Citrus sinensis).O estudo foi realizado em câmara de crescimento, simulando-se condições de temperatura média e de fotofase de verão (24º C e 13h) e de inverno (19º C e 11h) da região Central do Estado de São Paulo. As plantas foram submetidas a dois regimes hídricos: capacidade de campo e déficit hídrico. A sobrevivência de O. facialis foi menor quando mantida em "seedlings" sob déficit hídrico, independentemente das condições de temperatura ("verão" ou "inverno"). A taxa de ingestão de seiva, medida indiretamente pela excreção de "honeydew", foi maior nos tratamentos mantidos em capacidade de campo para as duas condições de temperatura. Comprovou-se, então, que o déficit hídrico do solo reduz a sobrevivência e a taxa de alimentação de O. facialis em "seedlings" de citros. Os resultados sugerem uma menor adequação da planta cítrica às cigarrinhas durante épocas mais secas do ano.

ABSTRACT The feeding behavior of the leafhopper vectors of Xylella fastidiosa, the causal agent of Citrus Variegated Chlorosis, can influence its transmission efficiency. The influence of soil water conditions and environmental temperature on survival and feeding behavior of the leafhopper Oncometopia facialis (Hemiptera: Cicadellidae) was evaluated on sweet orange (Citrus sinensis) seedlings. This study was carried out in a growth chamber adjusted for mean temperature and photophase of summer (24º C and 13h) and winter (19º C and 11h) seasons in the Central Region of Sao Paulo State. The plants were submitted to two soil water treatments: field capacity and water deficit. The survival of the O. facialis was lower on seedlings under water deficit, regardless of the temperature conditions (summer or winter). The sap ingestion rates, which were indirectly measured by the honeydew excretion, were higher on seedlings under field capacity for both temperature conditions. This study shows that soil water deficit reduces leafhopper survival and ingestion rates on citrus seedlings, thus providing evidence that host plant suitability to the vector is affected during the dry season.