Pedro Takao Yamamoto

Distribution and quantification of Candidatus Liberibacter americanus, agent of huanglongbing disease of citrus in São Paulo State, Brasil, in leaves of an affected sweet orange tree as determined by PCR.

Huanglongbing (HLB), an insect-transmitted disease of citrus, known for many years in Asia and Africa, has appeared in the state of São Paulo State (SSP), Brazil, in 2004, and the state of Florida, USA, in 2005. HLB endangers the very existence of citrus, as trees infected with the bacterial pathogen, irrevocably decline. In the absence of curative procedures, control of HLB is difficult and only based on prevention. Even though not available in culture, the HLB bacterium could be shown to be Gram-negative and to represent a new candidate genus, Candidatus Liberibacter, in the alpha subdivision of the Proteobacteria. Three Candidatus (Ca.) L. species occur: Ca. L. africanus in Africa, Ca. L. asiaticus in Asia, SSP, and Florida, and Ca. L. americanus in SSP. The liberibacters occur exclusively in the phloem sieve tubes. On affected trees, HLB symptoms are often seen on certain branches only, suggesting an uneven distribution of the Liberibacter. Occurrence of Ca. L. americanus, the major HLB agent in SSP, has been examined in 822 leaf samples from an affected sweet orange tree by two conventional PCR techniques and a newly developed real time (RTi) PCR, also used for quantification of the Liberibacter in the leaves. Even though RTi-PCR was able to detect as few as 10 liberibacters per gram of leaf tissue (l/g), no liberibacters could be detected in any of the many leaf samples from a symptomless branch, while in blotchy mottle leaves from symptomatic branches of the same tree, the Liberibacter titer reached values as high as 10(7)l/g. These results demonstrate the uneven distribution of the Liberibacter in HLB-affected trees.

Base científica para a erradicação de plantas sintomáticas e assintomáticas de Huanglongbing (HLB, Greening) visando o controle efetivo da doença

Instituto Agronomico do Parana - IAPAR, 86001-970, Londrina, PR, BrasilAutor para correspondencia: Jose Belasque Junior, e-mail: belasque@fundecitrus.com.br1. IntroducaoHuanglongbing (HLB), ou Greening, e a doenca mais importante e destrutiva da citricultura mundial (Bove, 2006; Gottwald et al., 2007a). Presente de forma endemica nos continentes asiatico e africano ha varias decadas, essa doenca foi recentemente detectada nos dois principais paises produtores de citros, Brasil e Estados Unidos (Colleta Filho et al., 2004; Halbert, 2005; Teixeira et al., 2005). O Brasil detem 30% da producao mundial de laranja e 59% da producao de suco de laranja (Neves et al., 2007). Sao Paulo e Florida dominam a oferta mundial, um caso raro em se tratando de commodities agricolas. O sistema agroindustrial citricola brasileiro movimenta anualmente R

Population Dynamics of Diaphorina citri Kuwayama (Hemiptera: Psyllidae) in Citrus Orchards in the North of Sao Paulo State, Brazil

9 bilhoes e gera mais de 400 mil empregos diretos e indiretos. Pelos danos que causa e pela dificuldade do seu manejo, o HLB coloca em risco esse importante setor do agronegocio brasileiro. Ha necessidade de acoes conjuntas urgentes envolvendo citricultores, industrias processadoras e os governos federal e estaduais. Em 17 de Outubro de 2008 entrou em vigor a Instrucao Normativa n

Distribuição espacial de Dilobopterus costalimai young (Hemiptera: Cicadellidae) em citros na região de Taquaritinga, SP

The purpose of this research was to study the population dynamics of Diaphorina citri Kuwayama in citrus orchards in the north area of Sao Paulo State. The study was carried out in 16 citrus orchards, being six of them in Catanduva area, five in Barretos and five in Monte Azul Paulista. A vacuum sucker machine was used to collect the insects. The highest density of D. citri occurred in the end of the spring time and in the beginning of the summer. During autumn and winter the population was low. Most of the insects were captured in the Catanduva area, followed by Barretos and Monte Azul Paulista. Population was considered constant in all the Catanduva orchards, in four orchards in Monte Azul Paulista, and in only two orchards in Barretos.

Lethal and Sublethal Effects of Insecticides Used on Citrus, on the Ectoparasitoid Tamarixia radiata

Dilobopterus costalimai Young is one of the most important pests in Brazilian citrus crop because it transmits Xylella fastidiosa, a bacterium that causes Citrus Variegated Chlorosis (CVC). We studied the spatial distribution of the insect, in order to develop a sampling plan to determine the proper moment to control the pest. D. costalimai was collected fortnightly, between 11/1999 until 4/2000, in a thirteen-year-old citrus orchard, where no insecticide was sprayed against this insect. Thirteen samples were performed in a grid of 100 yellow sticky traps (10 x 25 cm) in Taquaritinga County, Sao Paulo State. The variance of the sampling was higher than the mean in all samplings, with index ratio variance/mean (I) between 1.07 and 2.90, Morisita index between 1.07 and 1.57, k exponent of negative binomial distribution between 1.56 and 14.79. The chi-square goodness-of-fit test to Poisson distribution were not significant in seven samplings, however adjust to negative binomial were not significant in all samplings. The index b of Taylor´s Power Law was 1.3054, thus showing an aggregated distribution for this species in the field.

First report of Fingeriana dubia cavichioli transmitting Xylella fastidiosa to citrus

Huanglongbing (HLB) is a disease associated with the bacteria “Candidatus Liberibacter spp.” and has been devastating citrus orchards around the world. Its management involves control of the insect vector, the Asian citrus psyllid Diaphorina citri Kuwayama. However, the indiscriminate use of chemicals has caused pest outbreaks and eliminated the natural enemies of the vector, such as the parasitoid Tamarixia radiata (Waterston), the main agent for biological control of D. citri. This study assessed the lethal and sublethal effects of insecticides recommended for integrated production of citrus on the parasitoid T. radiata. When adult parasitoids were exposed to residues of 25 insecticides, 20% of them, i.e., gamma-cyhalothrin, etofenprox, azadirachtin, tebufenozide and pyriproxyfen, were considered as harmless (Class 1), 12% as slightly harmful (Class 2), 12% as moderately harmful (Class 3) and 56% as harmful (Class 4), according to the classification proposed by the IOBC/WPRS. Afterward, 14 insecticides (5 harmless and 9 harmful) were sprayed on the parasitoid pupae. Of the 14 insecticides tested, only the organophosphates dimethoate and chlorpyrifos affected the parasitoid emergence. The effects of insecticides on the parasitism capacity of adults exposed to residues of azadirachtin, etofenprox, gamma-cyhalothrin, pyriproxyfen and tebufenozide (harmless) were also evaluated. Tebufenozide and gamma-cyhalothrin affected the parasitism of the F0 generation, but did not affect the emergence of the F1 and F2 generations. Therefore, for an effective IPM program, selective insecticides or harmful pesticides to adult parasitoids could be used in the field, provided that the adults do not occur naturally and the chemical applications do not coincide with parasitoid releases.

Flutuação populacional de cigarrinhas (Hemiptera: Cicadellidae) em pomar cítrico em formação

Primeiro relato de Fingeriana dubia Cavichioli transmitindo Xylella fastidiosa para Citros Este trabalho relata, pela primeira vez, a transmissão da bactéria Xylella fastidiosa, agente causal da clorose variegada dos citros, por Fingeriana dubia Cavichioli (Hemiptera: Cicadellidae: Cicadellinae). Uma planta de três testadas mostrou-se infectada e apresentou sintomas típicos da CVC aproximadamente 9 meses após a inoculação por esta espécie de cigarrinha.

Lethal and Sublethal Impacts of Acaricides on Tamarixia radiata (Hemiptera: Eulophidae), an Important Ectoparasitoid of Diaphorina citri (Hemiptera: Liviidae)

O proposito deste trabalho foi estudar a flutuacao populacional de cigarrinhas em pormar citrico em formacao. A populacao de cigarrinhas foi monitorada usando-se armadilhas amarelas. A especie mais abundante foi Bucephalogonia xanthophis (Berg). Baixas populacoes de Acrogonia sp., Dilobopterus costalimai Young e Oncometopia facialis (Signoret) foram detectadas durante o experimento.

Distribuição espacial de Toxoptera citricida (Kirkaldy) (Hemiptera: Aphididae) na cultura de citros

ABSTRACT The use of synthetic acaricides for management of pest mites may alter the efficacy of the ectoparasitoid Tamarixia radiata (Waterston) in biological control of Diaphorina citri Kuwayama, the vector of the bacteria associated with huanglongbing (HLB) in citrus orchards.We evaluated the toxicity of 16 acaricides that are recommended for the control of citrus-pest mites to T. radiata. Acrinathrin, bifenthrin, carbosulfan, and fenpropathrin caused high acute toxicity and were considered harmful (mortality >77%) to T. radiata. Abamectin, diflubenzuron, etoxazole, fenbutatin oxide, fenpyroximate, flufenoxuron, hexythiazox, propargite, spirodiclofen, and sulfur caused low acute toxicity and affected the parasitism rate and emergence rate of adults (F1 generation), and were considered slightly harmful to T. radiata. Dicofol and pyridaben did not affect the survival and action of the ectoparasitoid, and were considered harmless. In addition to its acute toxicity, carbosulfan caused mortality higher than 25% for >30 d after application, and was considered persistent. Acrinathrin, bifenthrin, fenpropathrin, fenpyroximate, propargite, and sulfur caused mortalities over 25% until 24 d after application and were considered moderately persistent; abamectin was slightly persistent, and fenbutatin oxide was short lived. Our results suggest that most acaricides used to control pest mites in citrus affect the density and efficacy of T. radiata in the biological control of D. citri. However, further evaluations are needed in order to determine the effect of these products on this ectoparasitoid under field conditions.

Population Dynamics of Diaphorina citri Kuwayama (Hemiptera: Liviidae) in Orchards of ‘Valencia’ Orange, ‘Ponkan’ Mandarin and ‘Murcott’ Tangor Trees

O estudo da distribuicao espacial de pragas e fundamental para elaboracao de planos de amostragem para o uso do manejo integrado de pragas. Para o afideo Toxoptera citricida (Kirkaldy), estudou-se a distribuicao espacial em talhoes de pomares de citros comerciais de laranja-doce [Citrus sinensis (L.) Osbeck] da variedade Pera, com 5; 9 e 15 anos de idade, durante o periodo de setembro de 2004 a abril de 2005. Foram realizadas 14 amostragens de numero 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 a planta, a 1,5 m de altura aproximadamente. As armadilhas foram distribuidas na area, a cada cinco plantas na linha, em linhas alternadas, totalizando 137 armadilhas no talhao com 5 anos, 140 no talhao com 9 anos e 80 no talhao com 15 anos. Os indices de dispersao utilizados foram: razao variância media (I), indice de Morisita (Id), coeficiente de Green (Cx) e expoente k da distribuicao Binomial Negativa. O indice que melhor representou a agregacao do pulgao foi o expoente k da distribuicao Binomial Negativa, e a distribuicao binomial negativa foi o modelo que melhor se ajustou aos dados. Atraves destas analises, verificou-se que a maioria das amostragens apresentou uma distribuicao agregada da populacao de T. citricida.