Valdir Atsushi Yuki

Occurrence, distribution, and relative incidence of five viruses infecting cucurbits in the state of Sao Paulo, Brazil

Cucurbits species grown in 38 of 40 agricultural regions in the state of São Paulo, Brazil, were surveyed for the relative incidence of Cucumber mosaic virus (CMV), Papaya ringspot virus-type W (PRSV-W), Watermelon mosaic virus-2 (WMV-2), Zucchini lethal chlorosis virus(ZLCV), and Zucchini yellow mosaic virus (ZYMV) during May 1997 and June 1999. Samples from 621 plants, representing eight cultivated species, six wild species, and one commercial hybrid (Cucurbita moschata × C. maxima), were analyzed by plate trapped antigen enzyme-linked immunosorbent assay (PTA-ELISA). PRSV-W and ZYMV were the most frequently found viruses, accounting for 49.1 and 24.8%, respectively, of 605 samples tested. ZLCV, CMV, and WMV-2 were detected in 7.8, 6.0, and 4.5% of 612, 497, and 423 samples tested, respectively. Double infection was found in 97 samples, and triple infection was found in 10 samples. Quadruple infection was detected in one C. pepo sample. Plants that were symptomatic but negative by PTA-ELISA might be due to abiotic agents, infection by virus for which antiserum was not available, such as Squash mosaic virus, or infection with an as yet uncharacterized virus.

Diversity and localization of bacterial endosymbionts from whitefly species collected in Brazil.

Whiteflies (Hemiptera: Aleyrodidae) are sap-sucking insect pests, and some cause serious damage in agricultural crops by direct feeding and by transmitting plant viruses. Whiteflies maintain close associations with bacterial endosymbionts that can significantly influence their biology. All whitefly species harbor a primary endosymbiont, and a diverse array of secondary endosymbionts. In this study, we surveyed 34 whitefly populations collected from the states of Sao Paulo, Bahia, Minas Gerais and Parana in Brazil, for species identification and for infection with secondary endosymbionts. Sequencing the mitochondrial Cytochrome Oxidase I gene revealed the existence of five whitefly species: The sweetpotato whitefly Bemisia tabaci B biotype (recently termed Middle East-Asia Minor 1 or MEAM1), the greenhouse whitefly Trialeurodes vaporariorum, B. tabaci A biotype (recently termed New World 2 or NW2) collected only from Euphorbia, the Acacia whitefly Tetraleurodes acaciae and Bemisia tuberculata both were detected only on cassava. Sequencing rRNA genes showed that Hamiltonella and Rickettsia were highly prevalent in all MEAM1 populations, while Cardinium was close to fixation in only three populations. Surprisingly, some MEAM1 individuals and one NW2 population were infected with Fritschea. Arsenopnohus was the only endosymbiont detected in T. vaporariorum. In T. acaciae and B. tuberculata populations collected from cassava, Wolbachia was fixed in B. tuberculata and was highly prevalent in T. acaciae. Interestingly, while B. tuberculata was additionally infected with Arsenophonus, T. acaciae was infected with Cardinium and Fritschea. Fluorescence in situ hybridization analysis on representative individuals showed that Hamiltonella, Arsenopnohus and Fritschea were localized inside the bacteriome, Cardinium and Wolbachia exhibited dual localization patterns inside and outside the bacteriome, and Rickettsia showed strict localization outside the bacteriome. This study is the first survey of whitely populations collected in Brazil, and provides further insights into the complexity of infection with secondary endosymionts in whiteflies.

Indigenous American species of the Bemisia tabaci complex are still widespread in the Americas

Bemisia tabaci is a complex of at least 36 putative cryptic species. Since the late 1980s, the Middle East-Asia Minor 1 species (MEAM1, formerly known as the B biotype), has emerged in many tropical and subtropical regions of the world and in some areas has displaced the indigenous populations of B. tabaci. Based on analysis of the mtCOI gene, two indigenous species native to America have been reported: New World (NW, formerly the A biotype) and New World 2 (NW2). NW is present at least in Argentina, Brazil, Martinique, Mexico, Texas and Venezuela, and NW2 in Argentina, Bolivia and Brazil. Wild plants (Euphorbia sp. and Ipomoea sp.), as well as important crops such as tomato, bean and cotton, are still hosts for native B. tabaci populations in the Americas. MEAM1 has not completely displaced the native B. tabaci from the Americas.

At least two indigenous species of the Bemisia tabaci complex are present in Brazil

Bemisia tabaci is one of the most important global agricultural insect pests, being a vector of emerging plant viruses such as begomoviruses and criniviruses that cause serious problems in many countries. Although knowledge of the genetic diversity of B. tabaci populations is important for controlling this pest and understanding viral epidemics, limited information is available on this pest in Brazil. A survey was conducted in different locations of São Paulo and Mato Grosso states, and the phylogenetic relationships of B. tabaci individuals from 43 populations sampled from different hosts were analysed based on partial mitochondrial cytochrome oxidase 1 gene (mtCOI) sequences. According to the recently proposed classification of the B. tabaci complex, which employs the 3.5% mtCOI sequence divergence threshold for species demarcation, most of the specimens collected were found to belong to the Middle East‐Asia Minor 1 species, which includes the invasive populations of the commonly known B biotype, within the Africa/Middle East/Asia Minor high‐level group. Three specimens collected from Solanun gilo and Ipomoea sp. were grouped together and could be classified in the New World species that includes the commonly known A biotype. However, six specimens collected from Euphorbia heterophylla, Xanthium cavanillesii and Glycine maxima could not be classified into any of the 28 previously proposed species, although according to the 11% mtCOI sequence divergence threshold, they belong to the New World high‐level group. These specimens were classified into a new recently proposed species named New World 2 that includes populations from Argentina. Middle East‐Asia Minor 1, New World and New World 2 were differentiated by RFLP analysis of the mtCOI gene using TaqI enzyme. Taq I analysis in silico also differentiates these from Mediterranean species, thus making this method a convenient tool to determine population dynamics, especially critical for monitoring the presence of this exotic pest in Brazil.

Ability of Aphis gossypii and Myzus persicae to Transmit Cucumber mosaic virus in Single and Mixed Infection with Two Potyviruses to Zucchini Squash

The main objective of this work was to investigate the ability of Aphis gossypii and Myzus persicae to transmit Cucumber mosaic virus (CMV) singly and mixed with two potyviruses (Papaya ringspot virus - type W, PRSV-W and Zucchini yellow mosaic virus, ZYMV), to zucchini squash plants (Cucurbita pepo). The results showed that the potyviruses in general were more efficiently transmitted by both species of aphids as compared to CMV. The transmission of PRSV-W, ZYMV and CMV separately was more efficient than in mixture.

First report of Bemisia tabaci Mediterranean (Q biotype) species in Brazil.

BACKGROUND The whitefly Bemisia tabaci is a major cosmopolitan pest and comprises a complex of more than 36 cryptic species that cause serious damage to agricultural crops worldwide. In this study, the Mediterranean species of B. tabaci, formerly known as Q biotype, was identified for the first time in Brazil. RESULTS Adult B. tabaci were collected from different localities and hosts from Rio Grande do Sul, the southernmost state of the country that borders Uruguay and Argentina. Partial sequencing of the mitochondrial cytochrome oxidase I (mtCOI) gene indicated that B. tabaci MED species appears to be restricted to the province of Barra do Quaraí, infesting Capsicum annuum cultivated in greenhouses and Ipomoea batatas in open fields. The partial mtCOI sequences obtained shared 100% nucleotide identity with reference sequences for the Q biotype reported from Uruguay. The secondary endosymbionts Hamiltonella and Cardinium were detected by PCR in the new identified MED species from Brazil, similarly to the Q biotype from Uruguay. CONCLUSION Our results indicate the presence of the MED species in Brazil. The close monitoring of this new identified species in the southern region of Brazil is essential to avoid its geographical expansion to more important agricultural areas in the country.

Only the B biotype of Bemisia tabaci is present on vegetables in São Paulo State, Brazil

Bemisia tabaci (Genn.) e considerada uma das mais importantes pragas em cultivos de hortalicas e ornamentais em todo o mundo. Baseado na analise da sequencia mitocondrial (citocromo oxidase I - mtCOI) foi proposto recentemente que B. tabaci deva ser considerado um complexo criptico de especies, contendo 11 grupos e 24 especies. Dois destes grupos: Middle East-Asia Minor e Mediterranean englobam os biotipos B e Q, respectivamente. Avaliou-se a sequencia mtCOI de especimes de B. tabaci coletados em regioes do estado de Sao Paulo, Brasil. Por PCR-RFLP utilizando-se a enzima Taq I, pode-se observar somente o padrao tipico de clivagem para o biotipo B. Comparando-se com sequencias consenso, todas as moscas brancas foram classificadas no grupo Middle East-Asia Minor e puderam ser separadas em quatro haplotipos, indicando prevalencia do biotipo B em areas de pimentao (Capsicum annuum L.), tomate (Solanum lycopersicum L.), cucurbitaceas e berinjela (Solanum melongena L.) do Estado de Sao Paulo.

Transmissão do Cowpea mild mottle virus pela mosca branca Bemisia tabaci biótipo B para plantas de feijão e soja

ABSTRACT The stem necrosis of soybean is caused by a virus of the Carlavirus and transmitted for the whitefly Bemisia tabaci , also infectad ofbeans and identified as Cowpea mild mottle virus (CpMMV). In thiswork biotype B for transmission of the virus in beans and soy hadbeen carried through tests for determination of the number of necessarywhiteflys B. tabaci. In the sequence two other tests had been carriedthrough, with 10 insects for plant. Periods of access to the acquisition(PAA) of ‘Jalo’ for ‘Jalo’, and the effect of periods of access to theinoculation (PAI) had been evaluated increase. Visually typical Marubayashi, J.M.; Yuki, V.A.; Wutke, E.B.. Transmission of the Cowpea mild mottle virus by whitefly Bemisia tabaci biotype B for plants ofbeans and soy. Summa Phytopathologica, v.36, n.2, p.158-160, 2010. Keywords: Carlavirus , vector, Phaseolus vulgaris , Glycine max , cultivars. Palavras-chave adicionais: Carlavirus , vetor, Phaseolus vulgaris , Glycine Max, cultivares.

Transmissão do Passion fruit woodiness Virus por Aphis gossypii (Glover) (Hemiptera: Aphididae) e colonização de maracujazeiro pelo vetor

The transmission of Passion fruit woodiness virus (PWV) by Aphis gossypii (Glover) was evaluated. In two independent experiments, A. gossypii transmitted PWV to passion fruit plants at the rates of 75% and 100%, when eight and twelve viruliferous aphids were deposited by plant, respectively. At the end of the tests, nymphs of A. gossypii were observed in some of the passion fruit plants, suggesting that the aphid species was colonizing the plants. This seems to be the first report of Passiflora edulis f. flavicarpa (Deneger) colonization by a species of aphid.

Transmissão experimental do Grapevine virus B pela cochonilha Pseudococcus longispinus Targioni-Tozzetti (Hemiptera: Pseudococcidae)

In the State of Sao Paulo, Brazil, there are two isolates of Grapevine virus B (GVB) associated with grapevine corky bark disease (GCB). Although serologically similar, they induce distinct reaction on some grape varieties. They are called GVB-C for common isolate and GVB-I for isolate obtained from the variety Italia. The objective of this work was to verify the transmission of both GVB isolates from infected to healthy plants by the mealybug Pseudococcus longispinus. The transmission of the virus was determined by visual analysis of symptoms, ELISA and RT-PCR. In all transmission experiments, grape indicator plants that had been exposed to presumably viruliferous mealybugs reacted in 8-12 months with a typical symptoms of GCB. Healthy LN-33 plants, maintained around one GCB-C affected LN-33 plant, highly infested by the mealybug, became infected with incidence of 54.2% after four years. Experimental inoculation of healthy LN-33 plants with viruliferous mealybugs resulted in infection rates of 46.2% for GVB-C and 40.0% for GVB-I, after three years. Although P. longispinus occurs eventually in Sao Paulo State vineyards, preventive control measures for this insect must be taken on areas where healthy clones of scion and rootstock varieties are maintained.