Citrus tristeza virus (CTV) is the causal agent of the Tristeza disease, reported for the first time in Argentina in 1930. The most efficient vector, Toxoptera citricida (Kirkaldy), is present in the country and therefore citrus plants are made with tolerant combinations variety / rootstock. Lemon plants (Citrus limon (L) Burm f.) grafted on sour orange (Citrus x aurantium, L.) are asymptomatic and yield and growth are not affected by the virus. However, when lemon is grafted on Citrus macrophylla (Wester) the rootstock is severely affected by stem pitting and the tree becomes stunted. There are diverse CTV strains that differ in their ability to move and accumulate in different host species, and that host species exerts strong selective pressure on the virus. Because of this, the objective of this study was to compare the CTV population of different lemon cultivars grafted on sour orange and C. macrophylla in a field trial planted in December 2013 and exposed to natural infection. The strains of the virus presents were detected by reverse transcription and polymerase chain reaction (RT-PCR) using five sets of specific primers of CTV genotypes (T30, RB, B165, T3 and VT). The T3 and RB genotypes were detected in all the analyzed samples, while the T30 genotype was absent. Some lemon trees grafted on sour orange showed a lower concentration of T3 and / or absence of the VT genotype, both considered severe and present in all lemon tree samples in C. macrophylla. The genotype B165 was found for the first time in lemon in the northwestern Argentina, and it was present in 85% of the samples analyzed, in all cultivars. The natural infection and composition of the CTV population were very homogeneous in all plants of the trial, regardless of the rootstock. Results would indicate that C. macrophylla is susceptible to the genotypes detected.

El virus de la tristeza de los cítricos (CTV) es el agente causal de la enfermedad de la tristeza, reportada por primera vez en Argentina en 1930. El vector más eficiente, Toxoptera citricida (Kirkaldy), está presente en el país, la enfermedad es endémica, y por lo tanto las plantaciones se realizan con combinaciones tolerantes copa/portainjerto. Las plantas de limonero (Citrus limon (L) Burm f.) injertadas en naranjo agrio (Citrus x aurantium, L.) son asintomáticas y su desarrollo y producción no son afectados por el virus. Sin embargo, cuando el limonero se injerta en Citrus macrophylla (Wester) se manifiestan en el portainjerto síntomas severos de acanaladuras o " stem pitting" en la parte área y raíces, y detención del crecimiento del árbol. Existen diversas cepas o genotipos de CTV que difieren en su habilidad de desplazamiento y multiplicación según la especie del hospedero, que ejerce una fuerte presión selectiva sobre el virus. Debido a esto, el objetivo de este estudio fue comparar la población del virus en diferentes cultivares de limonero injertados en naranjo agrio y en C. macrophylla en un ensayo de campo plantado en diciembre de 2013 y expuesto a infección natural. Los genotipos del virus presente se detectaron mediante la transcripción reversa y reacción en cadena de la polimerasa (RT-PCR), utilizando cinco juegos de cebadores específicos de genotipos de CTV (T30, RB, B165, T3 y VT). Los genotipos T3 y RB se detectaron en todas las muestras analizadas, mientras que el T30 estuvo ausente. Por su parte, el genotipo B165 se detectó por primera vez en limonero en la región del noroeste argentino y estuvo presente en el 85% de las muestras examinadas en todos los cultivares. Algunos limoneros injertados en naranjo agrio mostraron una menor concentración de T3 y/o ausencia del genotipo VT, ambos considerados severos y presentes en todas las muestras de limonero en C. macrophylla. A pesar de estas diferencias puntuales, en líneas generales la infección natural y composición de la población de CTV fue muy homogénea en todas las plantas del ensayo, independientemente del portainjerto, por lo que estos resultados indican que C. macrophylla es susceptible a los genotipos detectados.

RESUMO O objetivo deste estudo foi avaliar a atividade inseticida da fração hexânica e do composto poligodial obtidos de raízes de Drimys brasiliensis sobre a mortalidade de adultos e ninfas de um dia de Toxoptera citricida (pulgão-preto dos citros). Para a fração hexânica foram preparadas soluções nas concentrações de 0,12; 0,25; 0,50; 1,0 e 2,0 mg mL-1 e, para o composto poligodial, concentrações de 62,5; 125; 250 e 500 µg mL-1. Água e dimetilsulfóxido (5 µg mL-1) foram utilizados como controle. Para a fração hexânica foram testadas duas formas de aplicação: pulverizações sobre os insetos e imersão do ramo caulinar jovem de Citrus limonia na solução, o qual serviu como hospedeiro para os pulgões. A avaliação da mortalidade dos adultos e de ninfas foi realizada após 24 e 48 horas da aplicação das soluções. A fração hexânica de raízes ocasionou elevada mortalidade de ninfas e adultos. O menor valor de CL50 (0,301 mg mL-1) foi registrado para as ninfas quando as soluções foram aplicadas sobre o inseto. O composto poligodial, isolado da fração hexânica, e aplicado sobre o inseto, aumentou significativamente a mortalidade de adultos e ninfas, com valores de CL50 de 293,8 e 176,77 µg mL-1, respectivamente. A ação inseticida pode ser devida à presença deste composto.

ABSTRACT The aim of this study was to evaluate the insecticidal effects of a hexane fraction and polygodial compound obtained from Drimys brasiliensis roots on the mortality of adults and nymphs of Toxoptera citricida (black citrus aphid). For the hexane fraction, solutions of 0.12, 0.25, 0.50, 1.0, and 2.0 mg mL-1 were prepared, and for the compound, solutions of 62.5, 125, 250, and 500 µg mL-1 were prepared. A control with water and dimethylsulfoxide (5 µg mL-1) was also included. Two hexane-fraction-solution application methods were evaluated: spraying directly onto the insect, and submerging a young Citrus limonia shoots in the solution, which served as a refuge for the aphids. Nymph and adult mortality were assessed at 24 and 48 h after solution application. The hexane fraction caused high mortality amongst the T. citricida nymphs and adults. The lowest LC50 value (0.301 mg mL) was recorded in the nymphs when the solutions were applied directly onto the insects. The polygodial compound that was isolated from the hexane fraction significantly increased the mortality of adults and nymphs, with LC50 values of 293.8 and 176.77 µg mL-1, respectively. The insecticidal activity observed may have been caused by this compound.

Abstract Background Studies upon mycobiota associated to pest has been commonly focused only on entomopathogenic species with the aim to use them as biocontrol agents, without considering others fungal species probably related to crop diseases. Objectives Analyze the mycobiota associated to pest insect corpses from maize in the Queretaro State to address the impact they have in agriculture. Methods The identification of fungal isolated was carried out by classic taxonomy and phylogenetic analysis using sequences of ADNr ITS1, 5.8S, and ITS2. Results and conclusions Eighteen fungal strains were isolated from insect cadavers, which are catalogued as economic importance pest in the Queretaro State. The fungi belong to the genera Fusarium, Beauveria, and Purpureocillium, isolated from Melanoplus sp., Toxoptera citricida and Spodoptera frugiperda larvae as hosts respectively. The Fusarium species showed high prevalence in our samples, followed by B. bassiana and P. lilacinum, suggesting that they could be acting as natural biocontrol agents against pest, possibly pest insects could be acting as vectors transporting some species of phytopathogenic fungi among the crops.

Resumen Antecedentes Los estudios sobre la micobiota asociada a insectos plaga comúnmente se enfocan sólo a especies entomopatógenas para su uso en control biológico, sin considerar muchas otras que podrían estar involucrados en las enfermedades de las plantas de cultivo de interés. Objetivos Analizar la micobiota asociada a cadáveres de insectos plaga de maíz en el estado de Querétaro para conocer el impacto que tienen en los sistemas agrícolas. Métodos La identificación de las cepas aisladas de los insectos plaga se realizó mediante taxonomía clásica y un análisis filogenético de las secuencias de la región ITS1, 5.8S e ITS2 del ADNr. Resultados y conclusiones Se aislaron 18 cepas de hongos asociados a cadáveres de insectos catalogados como plagas de importancia económica en el estado de Querétaro. Los aislados pertenecen a los géneros Fusarium, Beauveria, y Purpureocillium aisladas de Melanoplus sp., Toxoptera citricida y larvas de Spodoptera frugiperda como hospederos. La presencia de especies del género Fusarium presentó una alta prevalencia en el muestreo, seguido por B. bassiana y P. lilacinum sugiriendo que pueden estar actuando en el control de plagas de forma natural, pero también los insectos plaga pueden actuar como vectores de algunas especies de hongos fitopatógenos entre los cultivos.

Abstract The citrus tristeza virus (CTV) is a pathogen present in almost all citrus areas. It reduces production in plantations with susceptible rootstocks, such as sour orange trees. The aim of this study was to temporally characterize the behavior of CTV considering its population structure (PS), vigor, concentration in tissues and availability of vectors, this on the basis of an analysis of the thermal conditions in Yucatán. In two sweet orange (C. sinensis) orchards in Yucatán, trees grafted onto sour orange (C. aurantium) were sampled and evaluated in terms of vigor for 12 years. Samples were analyzed by immunoprinting, single-strand conformation polymorphism (SSCP), and specific amplifications by real-time and conventional polymerase chain reaction (PCR). The incidence of CTV increased 40 % in four years. All samples analyzed (81) were negative for severe isolates; only T-30 isolates and minor changes in tree vigor were identified. The PS indicated changes with a tendency towards complexity (11 electrophoretic patterns in six haplotypes), a similarity coefficient of 0.80 and intrapopulation diversity of 65 %. The thermal regime (TR) was restrictive during 75 % of the year for CTV transmission and the optimum development of vector aphids. Pathogen PS and TR have contributed to the fact severe CTV epidemics have not been recorded; therefore, sour orange continues as a key element in the region’s citrus production despite the risk involved (commercializing propagating material that does not comply with NOM 079-FITO-2002).

Resumen El virus de la tristeza de los cítricos (CTV) es un patógeno presente en casi todas las áreas citrícolas; el cual, reduce la producción en plantaciones con portainjertos susceptibles, como el naranjo agrio. El objetivo de este estudio fue caracterizar temporalmente el comportamiento del CTV considerando su estructura poblacional (EP), vigor, concentración en tejidos y disponibilidad de vectores. Esto último a partir del análisis de las condiciones térmicas en Yucatán. Se muestrearon y evaluaron en vigor durante 12 años los árboles de dos huertas de naranjo dulce (C. sinensis), injertados en agrio (C. aurantium) en Yucatán. Las muestras se analizaron por inmunoimpresión, polimorfismo de conformación de cadena simple (SSCP) y amplificaciones específicas por la reacción en cadena de la polimerasa (PCR) en punto final y tiempo real. La incidencia de CTV se incrementó 40 % en cuatro años. Todas las muestras analizadas (81) fueron negativas para aislados severos; solo se identificaron aislados tipo T-30 y cambios menores en el vigor de los árboles. La EP indicó cambios con tendencia a la complejidad (11 patrones electroforéticos en seis haplotipos), coeficiente de similaridad de 0.80 y diversidad intrapoblacional de 65 %. El régimen térmico (RT) fue restrictivo durante 75 % del año para la transmisión del CTV y el desarrollo óptimo de áfidos vectores. La EP del patógeno y el RT han contribuido a que no se registren epidemias severas de CTV; por lo cual, el naranjo agrio continúa como un elemento clave en la producción citrícola de la región con el riesgo que esto implica (comercializar material propagativo que no cumple la NOM 079-FITO-2002).

Citric (Citrus sinensis L.) commercial vegetable gardens were studied, located in the main producing regions of Yucatán from 2003 to 2006 and in Tamaulipas in 2004. In Yucatán it was carried out a space-time study of dispersion of citric tristeza, caused by Citrus tristeza virus, in presence of Toxoptera citricida Kirkaldy. The initial incidence (X0) was of 4.41% and the final (Xf) was of 39.33%. The aggregation indexes of Morisita and Lloyd dependent of the optimum size of quadrant showed an added pattern with values between 1.41 and 2.39. Also, isolations of Citrus tristeza virus were molecularly characterized to examine the diversity of current virus. Virus isolations were analyzed with single-strand conformation polymorphism, being observed up to two haplotypes by isolation and three types of patterns in Yucatán. In Tamaulipas, with the molecular characterization, three haplotypes were identified by isolation and seven patterns. The similarity coefficient calculated for these two populations of isolations was of 0.7, being assumed a common origin for both populations. The analysis of molecular variance indicated bigger variability inside the populations (69%) and between them (31%), proving that both citric regions share variants characterized as of moderate type, which can justify the absence of symptoms attributable to tristeza. The analyses carried out to identify dispersion pattern of the isolations in field didn't evidence the dispersion between trees and rows.

Se estudiaron huertas comerciales de cítricos (Citrus sinensis L.), ubicadas en las principales regiones productoras de Yucatán de 2003 a 2006 y en Tamaulipas en 2004. En Yucatán se realizó un estudio espacio-temporal de la dispersión de la tristeza de los cítricos, ocasionada por el Citrus tristeza virus, en presencia de Toxoptera citricida Kirkaldy. La incidencia inicial (X0) fue de 4.41% y la final (Xf) de 39.33%. Los índices de agregación de Morisita y Lloyd dependientes del tamaño óptimo de cuadrante, mostraron un patrón agregado con valores entre 1.41 y 2.39. Además, se caracterizaron molecularmente aislamientos del Citrus tristeza virus, para examinar la diversidad del virus presente. Se analizaron aislamientos del virus con single-strand conformation polymorphism, observándose hasta dos haplotipos por aislamiento y tres tipos de patrones en Yucatán. En Tamaulipas, con la caracterización molecular, se identificaron tres haplotipos por aislamiento y siete patrones. El coeficiente de similaridad calculado para estas dos poblaciones de aislamientos fue de 0.7, asumiéndose un origen común de ambas poblaciones. El análisis de varianza molecular, indicó mayor variabilidad dentro de las poblaciones (69%) y entre ellas (31%), comprobando que ambas regiones citrícolas, comparten variantes caracterizadas como de tipo moderado, mismo que puede justificar la ausencia de sintomatología atribuible a tristeza. Los análisis realizados para identificar el patrón de dispersión de los aislamientos en campo no evidenciaron la dispersión entre árboles e hileras.

O ecossistema citrícola abriga muitas espécies de inimigos naturais, entre eles Chrysoperla externa (Hagen, 1861) que apresenta um grande potencial como agente de controle biológico de pragas. Neste trabalho, objetivou-se avapar o efeito das presas Planococcus citri (Risso, 1813) e Toxoptera citricida (Kirkaldy, 1907) sobre o desenvolvimento das fases de larva e pupa de C. externa. O ensaio foi conduzido em sala cpmatizada a uma temperatura de 25±1ºC, 70±10% UR e fotofase de 12 horas, sendo os tratamentos constituídos pelo fornecimento contínuo e alternado dessas duas presas em cada ínstar do predador, além de ovos de Anagasta kuehniella (Zeller, 1879), utilizados para fins de comparação. Foram avaliados o tempo de vida e a viabilidade das fases de larva, pupa e do período larva-adulto de C. externa. Constatou-se que T. citricida fornecido isoladamente ao longo do desenvolvimento larval ou em dois ínstares consecutivos do predador, não foi uma presa adequada, constatando-se 100% de mortalidade no período larva-adulto. Quando as larvas alimentaram-se de P. citri fornecida em dois ínstares do predador, a viabilidade no período larva-adulto foi semelhante à dieta constituída por apenas ovos de A. kuehniella, exceto quando se alimentaram de T. citricida no primeiro ínstar.

The citrus-growing ecosystem houses a great deal of species of natural enemies, among them Chrysoperla externa (Hagen, 1861), which presents a great potential for use in the bipogical contrp of pests. The aim of this work was to evaluate the effects of the preys Planococcus citri (Risso, 1813) and Toxoptera citricida (Kirkaldy, 1907) on the development of larva and pupa of C. externa. The trial was carried out in an accpmatized room at 25±1ºC, 70±10% RH and 12-hour photophase, the treatments consisting of the continuous and alternate supply of those two preys in each instar of the predator, in apition to eggs of Anagasta kuehniella (Zeller, 1879) utilized for comparison purposes. Both the white mealybug and the aphids were given in sufficient amounts to the C. externa larvae to be able to feed ad libitum. The pfetime and the survival rate of the phases of larva, pupa and the larval-adult period of C. externa were evaluated. It was found that T. citricida given either singly along the larval development or in two consecutive instars of the predator was not an adequate prey, 100% of mortapty over the larval-adult period being found. When the larvae fed on P. citri, given in two instars of the predator, the survival rate in the larval-adult period was similar to the diet constituted of only A. kuehniella eggs, except when fed with T. citricida in the first instar.

Individuals of Toxoptera citricida (Kirkaldy) and Aphis spiraecola (Patch) collected in 16 commercial citrus orchards of the São Paulo and Minas Gerais States of Brazil were analyzed for virus presence. Orchards of Minas Gerais were selected because citrus trees exhibit symptoms of citrus sudden death (CSD) and in São Paulo due the presence of severe strains of Citrus tristeza virus (CTV), in order to detect genomic sequences of any of these strains that could be associated to CSD. Samples made up of 20 aphids from the localities of Comendador Gomes, Frutal, Prata and Uberlândia, in the State of Minas Gerais, a CSD associated virus (CSDaV) was often found through nested RT-PCR; in samples from São Paulo, none showed positive for the same primers. With the aim to find relationships between the presence of a specific strain of CTV and the expression of CSD, specific probes were used for sequences associated to severity of isolates. The results were negative and the most promising option was to detect CTV sequence variants acquired by aphids through SSCP, to determine if there was a preference for any of the variants. No CTV sequence variants exclusive to trees with CSD symptoms were detected in aphids, but CTV was more prevalent than CSDaV in both aphid species (98 and 90% vs. 42 and 10%). Results confirm the presence of CSDaV in aphids colonizing trees with or without CSD symptoms. However, detection of CSDaV was more frequent under the CSD condition and five times higher in T. citricida.

Se analizaron individuos de Toxoptera citricida (Kirkaldy) y Aphis spiraecola (Patch) recolectados en 16 huertas comerciales de cítricos en los Estados de São Paulo y Minas Gerais, para evaluar la presencia de virus. Las huertas de Minas Gerais se seleccionaron debido a que los árboles de cítricos exhibían síntomas de muerte súbita de los cítricos (MSC) y en São Paulo debido a la presencia de variantes severas del Citrus tristeza virus (CTV), que pudieran permitir detectar secuencias genómicas de cualquiera de estas variantes en asociación con MSC. En grupos muestrales de 20 áfidos, provenientes de las localidades de Comendador Gomes, Frutal, Prata y Uberlândia, del Estado de Minas Gerais, se encontró con frecuencia un CSD associated virus (CSDaV) mediante el uso de RT-PCR y PCR anidado; en muestras de São Paulo, ninguna fue positiva para los mismos iniciadores. Con el objetivo de encontrar relación entre la presencia de una variante específica de CTV y la expresión de MSC, se usaron sondas específicas para secuencias asociadas a la severidad de los aislamientos. Los resultados fueron negativos y la opción más viable fue detectar variantes de secuencias de CTV adquiridas por áfidos a través de SSCP para determinar si existió preferencia por alguna de las variantes. No se detectaron en áfidos variantes de secuencias de CTV exclusivas a árboles con síntomas de MSC, pero el CTV fue más común que el CSDaV en ambas especies de áfidos (98 y 90% vs. 42 y 10%). Los resultados confirman la presencia del CSDaV en áfidos que colonizaron árboles con o sin síntomas de MSC. Sin embargo, la detección del CSDaV fue más frecuente en la condición de MSC y cinco veces mayor en T. citricida.

A utilização de extratos de plantas pode ser uma alternativa para o controle de pragas. Dentre as plantas com atividade inseticida, destacam-se a erva-de-rato (Palicourea marcgravii) e o subproduto (manipueira) da produção de farinha de mandioca (Manihot esculenta), plantas comuns na região Amazônica. Esse trabalho teve, como principal objetivo, investigar o potencial inseticida da manipueira e do extrato de erva-de-rato sobre Toxoptera citricida (pulgão-preto do citros). Os extratos liofilizados de manipueira e de erva-de-rato foram pulverizados sobre plantas de citros contendo pulgões em cinco concentrações (10mg/ml, 20mg/ml, 30mg/ml, 40mg/ml e 50mg/ml). Todas as concentrações analisadas causaram mortalidade dos pulgões superior a 50%, sendo que a maior concentração causou a mortalidade de todos os insetos. O potencial destes extratos demonstrado no experimento coloca os mesmos como uma alternativa ao uso de inseticidas sintéticos no controle do pulgão-preto dos citros.

The utilization of plant extracts might be an alternative for the control of crop pests. Between the plants with insecticide potential, stands-out: Erva-de-rato (Palicourea marcgravii) and the Cassava, a byproduct of the manipueira (Manihot esculenta),common plants in the amazon region. That work had as main objective , to investigate the insecticide potential of Manihot esculenta (manipueira of cassava) and Palicourea marcgravii (erva-de-rato) on Toxoptera citricida (brown citrus aphid), in experimental conditions. The freeze dryed Manipueira and and Erva-de-rato extracts, were sprayed on citrus plants infected by brown citros aphid. In laboratory, extracts of these two plants were obtained in five concentrations (10mg/ml, 20mg/ml, 30mg/ml, 40mg/ml and 50mg/ml). All the analyzed concentrations (10 to 50mg/ml) caused mortality on T. citricida of above 50%, and the higher concentration of 50mg/ml caused the mortality of all the insects (n = 100%) in application processes contact. The potential of these extracts, as demonstrated in the tests, confirms that they can be an insecticide alternative, for the control of the brown citrus aphid.

Os afídeos são importantes pragas em citros como vetores de vírus fitopatogênicos. O objetivo do trabalho foi avaliar a diversidade de espécies de afídeos alados e a ocorrência estacional dos afídeos em um pomar de citros localizado em Taiúva, SP. Para as coletas de afídeos foram utilizadas armadilhas do tipo bandejas amarelas com água e placas adesivas amarelas. Foram realizadas quatro amostragens semanais em cada estação climática, durante o ano agrícola de 2004/2005. Foram capturados exemplares de afídeos das espécies: Aphis gossypii Glover, Aphis spiraecola Patch, Toxoptera citricida Kirkaldy e Toxoptera aurantii (Boyer de Fonscombe), Rhopalosiphum maidis (Fitch), Pentalonia nigronervosa Coquerel, Uroleucon ambrosie (Thomas) e Acyrthosiphon bidenticola Smith. As espécies A. spiraecola e T. citricida foram as mais abundantes, sendo caracterizadas como espécies comuns em todo o período avaliado. Coletaram-se mais afídeos alados no outono/2004, em relação às demais estações e maior quantidade e diversidade de espécies de afídeos foi obtida em bandejas com água.

The aphids are important pests of the citrus orchards, as they act as vectors of the phytopathogenic virus. The research aimed to estimate the diversity of the species of winged aphids and the occurrence in each season in a citrus orchard of citrus in Taiúva, State of São Paulo. The yellow trap type Moericke and yellow trap stick were used for the catches, on four weeks samplings, in each season, from April/2004 until April/2005. The species colleted were Aphis gossypii Glover, Aphis spiraecola Patch, Toxoptera citricida Kirkaldy e Toxoptera aurantii (Boyer de Fonscombe), Rhopalosiphum maidis (Fitch), Pentalonia nigronervosa Coquerel, Uroleucon ambrosie (Thomas) e Acyrthosiphon bidenticola Smith. The species A. spiraecola and T. citricida were the most abundant, and classificated as common species. A peak of winged applied capture was during the Autumn/2004, and the yellow trap with water captured more aphids than the yellow trap stick.

En 1976 se encuentra el principal transmisor del virus de los cítricos en Venezuela, Toxoptera citricida Kirk., en 1979 ocurre el primer foco de árboles muertos por el virus. Estos acontecimientos, hicieron que se introdujeran al país diferentes cultivares de cítricos para ser evaluados como portainjertos. Sin embargo, poco es lo que se conoce sobre la característica del fruto de esos materiales citrícolas. El objetivo del presente trabajo fue estudiar algunas características del fruto de ocho portainjertos para cítricos: Citrus volkameriana Pasq. (VOL), los citrumelos Poncirus trifoliata Raf. x Citrus paradisi Macf. Swingle (SWI) y Yuma (YUM), los citranges Poncirus trifoliata Raf. x Citrus sinensis Osb. Carrizo (CAR), Troyer (TRO) y Uvalde (UVA), mandarino Cleopatra (CLE) Citrus reshni ex Hort. Tan y Citremon 1449 Poncirus trifoliata Raf. x Citrus limon L. Se tomaron cinco árboles por portinjerto de tamaño y vigor uniformes, a cada árbol se le cosecharon diez frutos al azar y se determinó peso promedio, diámetro distal y ecuatorial, y grosor de cáscara. Además, se calculó la relación entre ambos diámetros, número de semillas por frutos, por 100 g, por kg y peso promedio de la semilla. En este trabajo se presentan los resultados del estudio de algunas características del fruto de ocho portainjertos para cítricos.

In 1976 was found for the first time in Venezuela the citrus tristeza virus transmitter, the Toxoptera citricida Kirk., and in 1979 occurs the first outbreak by the death of trees. All of those successes brought about the introduction of different Citrus cultivars to be evaluated as rootstocks. However, little is known about the fruit characteristics of the introduced rootstocks. The objective of this work was to study the fruit characteristics of eight Citrus rootstocks: Citrus volkameriana Pasq. (VOL), the citrumelos Poncirus trifoliate Raf. x Citrus paradisi Macf. Swingle (SWI) and Yuma (YUM), the citranges Poncirus trifoliate Raf. x Citrus sinensis Osb. Carrizo (CAR), Troyer (TRO) and Uvalde (UVA), Cleopatra mandarin (CLE), Citrus reshni ex Hort. Tan., and Citremon 1449 (CIT) Poncirus trifoliate Raf. x Citrus limon L. There were selected five trees for each rootstock of uniform size and vigor. From each tree ten fruits were harvested in a randomize form, and we measured the mean weight, distal and equatorial fruit diameter, thickness of rind and number of seeds. In addition, it was calculated the distal/equatorial relation, mean seed number by fruit in a 100 g and a kilogram base, and seed weight. In this paper it is shown the characteristics of the fruits of the evaluated rootstocks.

O objetivo deste estudo foi investigar se existe interação olfativa no sistema tritrófico entre Lysiphlebus testaceipes Toxoptera citricida e Citrus aurantium. A resposta de machos e fêmeas de L. testaceipes a diferentes fontes de odor da planta hospedeira C. aurantium, o afideo parasita T. citricida e o complexo afideo-planta foram investigados com um olfatômetro do tipo tubo em Y. Os experimentos de laboratório foram conduzidos, expondo-se machos e fêmeas de L. testaceipes de diferentes idades, individualmente, a oito tratamentos com diferentes fontes de odor. A resposta do parasitóide foi tomada depois de 15 minutos de exposição aos voláteis de diferentes fontes de odor, baseando-se na orientação dos parasitóides a uma câmara particular. Setenta por cento de L. testaceipes machos e fêmeas, exibiram maior atração ao odor das folhas infestadas pelo afídeo. Não houve diferença significativa entre idade e entre sexo do parasitóide na sua escolha do odor. Os compostos orgânicos liberados por estas combinações agiram como semioquímicos na interação tritrófica, o que indica que afídeos, ao se alimentarem das folhas, induzem atração no parasitóide L. testaceipes.

The objective of this study was to establish whether there are olfactory interactions in the Lysiphlebus testaceipes Toxoptera citricida and Citrus aurantium tritrophic system. The response of male and female L. testaceipes to different odour sources of the host plant C. aurantium, the aphid host T. citricida and aphid-plant complex were investigated using a Y-tube olfactometer. Laboratory experiments were conducted by exposing individually aged male and female L. testaceipes to eight different odour treatments. Response of the parasitoids was taken after 15 min exposure to the volatiles from the different odour sources and based on their orientation to the particular chamber. Seventy percent of both male and female L. testaceipes showed high attractivity to aphid infested leaves. There was no significant difference based on age and sex of the parasitoid on their choice of odour. The organic compounds released by these combinations acted as semiochemicals in the tritrophic interactions and it is suggested that insect feeding induced attraction of the parasitoid L. testaceipes.

O estudo da distribuição espacial de pragas é fundamental para elaboração de planos de amostragem para o uso do manejo integrado de pragas. Para o afídeo Toxoptera citricida (Kirkaldy), estudou-se a distribuição espacial em talhões de pomares de citros comerciais de laranja-doce [Citrus sinensis (L.) Osbeck] da variedade Pêra, com 5; 9 e 15 anos de idade, durante o período de setembro de 2004 a abril de 2005. Foram realizadas 14 amostragens de número de T. citricida em intervalos aproximados de 15 dias entre as mesmas, utilizando-se de armadilhas adesivas de cor amarela (0,11 x 0,11 m) fixadas à planta, a 1,5 m de altura aproximadamente. As armadilhas foram distribuídas na área, a cada cinco plantas na linha, em linhas alternadas, totalizando 137 armadilhas no talhão com 5 anos, 140 no talhão com 9 anos e 80 no talhão com 15 anos. Os índices de dispersão utilizados foram: razão variância média (I), índice de Morisita (Idelta), coeficiente de Green (Cx) e expoente k da distribuição Binomial Negativa. O índice que melhor representou a agregação do pulgão foi o expoente k da distribuição Binomial Negativa, e a distribuição binomial negativa foi o modelo que melhor se ajustou aos dados. Através destas análises, verificou-se que a maioria das amostragens apresentou uma distribuição agregada da população de T. citricida.

The study of insects' spatial distribution is fundamental to elaborate potential sampling plans to be used in integrated pest management. Spatial distribution of Toxoptera citricida was studied in plots of commercial orange orchards (Citrus sinensis) from 'Pêra' variety of 5, 9 and 15 years old, respectively, from September 2004 to April 2005. It was carried through 14 fortnightlies Toxoptera citricida samplings numbers, utilizing yellow adhesive traps (0.11 x 0.11 m) settled on the plant at 1.5 m of height approximately. The traps were distributed in the area each five plants in the line, in alternated lines, totalizing 137 traps in the 5 years plot, 140 in the 9 years plot and 80 in the 15 years plot. The dispersion indexes used were: variance/mean relationship (I), index of Morisita (Idelta), coefficient of Green (Cx) and k exponent of negative binomial distribution. The best aggregation index was the k exponent of negative binomial distribution and negative binomial distribution was the best of the data models. Through these analyses it was verified that most of the samplings presented an aggregated distribution of the brown citrus aphid population.

A citricultura fluminense vem sofrendo com os problemas fitossanitários, levando a baixa produção. Esse problema está ligado ao baixo conhecimento das espécies de insetos associado ao citros. O objetivo do trabalho foi estudar a distribuição geográfica das espécies de insetos fitófagos associados aos citros em 17 municípios do estado do Rio de Janeiro, de janeiro de 2000 a junho de 2001 em quatro regiões: Baixada Fluminense, Região Serrana, Região das Baixadas Litorâneas (região citrícola) e Região Noroeste do estado. As amostragens foram realizadas em um pomar por município, através da metodologia presença-ausência. Em três municípios foi verificada a ocorrência das 11 espécies e em outros três municípios observou-se menor número de espécies, apenas seis. As espécies com maior distribuição geográfica foram: Aleurothrixus floccosus (Maskell) e Selenaspidus articulatus (Morgan), ocorrendo em 16 municípios. As duas espécies com menor distribuição foram Lepidosaphis beckii (Newman) e Toxoptera citricida (Kirkaldy), presentes em sete e 10 municípios respectivamente.

The phytosanitary problems leading to lower citrus production in the state of Rio de Janeiro are due to the insufficient knowledge on insect species affecting citrus orchards. The objective of this research was to study the geographic distribution of phytophagous insect species, associated with citrus production, in 17 municipalities of Rio de Janeiro, from January 2000 to June 2001. The municipalities are located in four regions: Baixada Fluminense (the lowland region), Região Serrana (the mountain region), Região das Baixadas Litorâneas (the citrus producing marshland region) and Região Noroeste (the Northern region). Samples were collected from one orchard in each municipality by means of the presence or absence methodology. Eleven species were found in three municipalities and six species were found in three others. The species Aleurothrixus floccosus (Maskell) and Selenaspidus articulatus (Morgan) were found in 16 municipalities. Lepidosaphis beckii (Newman) and Toxoptera citricida (Kirkaldy) were found in only seven and 10 municipalities, respectively.

O controle biológico de insetos vetores de Phyllocnistis citrella em citros tem se mostrado ineficiente e o uso de inseticidas apresenta poucas opções. O objetivo do trabalho foi avaliar a eficiência de inseticidas sistêmicos, aplicados via tronco, no controle de Oncometopia facialis (Signoret) (Hemiptera: Cicadellidae), Phyllocnistis citrella Staiton (Lepidoptera: Gracillaridae) e Toxoptera citricida (Kirkaldy) (Hemiptera: Aphididae) em citros. A eficiência para O. facialis foi determinada pelo método de confinamento, utilizando-se 5 cigarrinhas adultas por repetição. Para P. citrella avaliou-se o número de folhas com lagartas em 3 ramos/planta e para T. citricida o número de ramos infestados. O acefate Pellet 970, vamidotion CE 300, monocrotofós CE 400, acetamipride PM e SL, e imidaclopride SL, nas doses testadas, controlam O. facialis, mas com períodos residuais variando de 12 a 104 dias, sendo os mais eficientes acetamipride SL (1,0 g i.a. por planta) e imidaclopride (1,0 g i.a. por planta). Os inseticidas acefate, vamidotion, monocrotofós, acetamipride e imidaclopride foram eficientes no controle de T. citricida e de P. citrella, com exceção de acetamipride PM nas doses de 0,4 e 0,6 g i.a. por planta. Acetamipride e imidaclopride apresentaram período de controle para P. citrella superior a 42 dias.

Methods of biological control of Phyllocnistis citrella in citrus are inefficient and chemical control is limited to a few options. The purpose of this study was to determine the efficiency of systemic insecticides to control Oncometopia facialis (Signoret) (Hemiptera: Cicadellidae), Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), and Toxoptera citricida (Kirkaldy) (Hemiptera: Aphididae) in citrus plant. The tests was performed enclosing the insects on branches, using five adults of O. facialis per plants. The citrus leaf miner were assessed on three new branches per plant, and for aphids, the number of infested branches was quantified. The insecticides acephate Pellet 970, vamidothion CE 300, monocrotophos CE 400, acetamiprid PM e SL, and imidacloprid SL were efficient to control O. facialis, however with different residual periods, ranging from 12 to 104 days. Acetamiprid SL (1.0 g a.i./plant) and imidacloprid were the most efficient. All tested insecticides were efficient to control T. citricida and P. citrella, except acetamiprid PM (0.4 and 0.6 g a.i./plant). Acetamiprid and imidacloprid showed a period for citrus leaf miner control greater than 42 days.

Aphid samplings were accomplished at three "Valencia" orange orchards in the municipalities of Hidalgo, Padilla and Victoria, Tamaulipas, from September 1995 to April 1996 during 12 collecting dates. Fifteen trees per orchard were sampled and infested shoots were collected from three strata of the tree height. The aphid species found were Aphis gossypii (Glover), Aphis spiraecola (Patch), Aphis fabae (Scopoli) and Toxoptera aurantii (Boyer de Fonscolombe) in a contagious distribution; medium stratum was the most preferred. The absence of Toxoptera citricida (Kirkaldy) during the period of study was confirmed. Natural enemies found were four Coccinellidae species (Hippodamia sp., Cycloneda sp., Brachyacantha sp. and Stethorus sp.), two Syrphidae species (Ocyptamies sp. and Pseudodorus clavatus Fabricius), one Chrysopidae (Chrysoperla rufilabris Burmeister) and one Chamaemyiidae (Leucopis sp.) as predators; Lysiphlebus testaceipes (Cresson) (Braconidae) as primary parasitoid, and Alloxysta megouzae (Ashm.) (Cynipidae) as a secondary parasitoid.

Se realizaron muestreos de pulgones en tres huertas de naranja "Valencia" de los municipios de Hidalgo, Padilla y Victoria, Tamaulipas, desde septiembre de 1995 hasta abril de 1996 durante 12 fechas de colecta. Se muestrearon 15 árboles por huerta y se colectaron brotes infestados en cada uno de los tres estratos de altura de los árboles. Las especies de pulgones presentes fueron: Aphis gossypii (Glover), Aphis spiraecola (Patch), Aphis fabae (Scopoli) y Toxoptera aurantii (Boyer de Fonscolombe), presentando una distribución por contagio y siendo preferido el estrato medio del árbol. Se confirma la ausencia de Toxoptera citricida (Kirkaldy) durante el periodo de estudio. Los enemigos naturales fueron cuatro especies de Coccinellidae (Hippodamia sp., Cycloneda sp., Brachyacantha sp., y Stethorus sp.), dos de Syrphidae (Ocyptamies sp. y Pseudodorus clavatus Fabricius), una de Chrysopidae (Chrysoperla rufilabris Burmeister) y una de Chamaemyiidae (Leucopis sp.), Lysiphlebus testaceipes (Cresson) (Braconidae) como parasitoide primario, y Alloxysta megouzae (Ashm.) (Cynipidae) como parasitoide secundario.