Molecular phylogenetic and morphological analyses of Oidium heveae, a powdery mildew of rubber tree

Powdery mildew of rubber tree caused by Oidium heveae is an important disease of rubber plantations worldwide. Identification and classification of this fungus is still uncertain because there is no authoritative report of its morphology and no record of its teleomorphic stage. In this study, we compared five specimens of the rubber powdery mildew fungus collected in Malaysia, Thailand, and Brazil based on morphological and molecular characteristics. Morphological results showed that the fungus on rubber tree belongs to Oidium subgen. Pseudoidium. Nucleotide sequence analysis of the ribosomal DNA internal transcribed spacer (ITS) region and the large subunit rRNA gene (28S rDNA) were conducted to determine the relationships of the rubber powdery mildew fungus and to link this anamorphic fungus with its allied teleomorph. The results showed that the rDNA sequences of the two specimens from Malaysia were identical to a specimen from Thailand, whereas they differed by three bases from the two Brazilian isolates: one nucleotide position in the ITS2 and two positions in the 28S sequences. The ITS sequences of the two Brazilian isolates were identical to sequences of Erysiphe sp. on Quercus phillyraeoides collected in Japan, although the 28S sequences differed at one base from sequences of this fungus. Phylogenetic trees of both rDNA regions constructed by the distance and parsimony methods showed that the rubber powdery mildew fungus grouped with Erysiphe sp. on Q. phillyraeoides with 100% bootstrap support. Comparisons of the anamorph of two isolates of Erysiphe sp. from Q. phillyraeoides with the rubber mildew did not reveal any obvious differences between the two powdery mildew taxa, which suggests that O. heveae may be an anamorph of Erysiphe sp. on Q. phillyraeoides. Cross-inoculation tests are required to substantiate this conclusion. © The Mycological Society of Japan and Springer-Verlag 2005.

Influência da Qualidade das Lâminas no Desempenho Mecânico à Flexão de Painéis Compensados de Hevea brasiliensis

After concluding the main phase of commercial exploration of latex (about 30 years ago), rubber wood plantations can be utilized as an alternative source of wood for sawmills and other wood based products with more aggregate value; tendency already confirmed in countries of southeastern Asia. The main purpose of this research was to evaluate the influence of dynamic modulus of elasticity veneers on the mechanical performance in the bending of plywood made from Hevea brasiliensis. For this study, rubber tree veneers were sorted in three classes of dynamic modulus of elasticity: low (from 4887-7323 MPa), medium (from 8200-8948 MPa) and high (from 10979-13010 MPa). Panels were produced according to five treatments with different veneer classes and arrangements. Results showed significant effect of the treatments in the mechanical performance in the bending of panels. Panels with better mechanical performance were produced exclusively with medium and high dynamic modulus of elasticity. Panels made with low modulus of elasticity veneers presented lower mechanical performance even when combined with high modulus of elasticity veneers.

Population Fluctuation and Damage Caused by Phytophagous Mites on Three Rubber Tree Clones

Our aim was to investigate the population fluctuation and the damage caused by the phytophagous mites Calacarus heveae Feres, Tenuipalpus heveae Baker, and Eutetranychus banksi (McGregor) on clones FX 2784, FX 3864, and MDF 180 in rubber tree crops from southeastern Bahia, Brazil. Moreover, we tested for the influence of climatic variables on occurrence patterns of these species throughout weekly samples performed from October to April. The infestation peaks was between mid-January and late February. The clones FX 2784 and FX 3864 had the highest infestations and more severe damage possibly caused by C. heveae, which was the most frequent and abundant species in all clones. We found that sunlight duration and rainfall were the most important factors for C. heveae while T. heveae was affected by rainfall and temperature. Eutetranychus banksi was only affected by sunlight duration. However, the best models had low goodness of fit. We concluded that the clones FX 2784 and FX 3864 had a higher susceptibility to mite attack, and the association between climatic variables and favorable physiological conditions were determinant for the population increase of the species from January to April. © 2012 Sociedade Entomológica do Brasil.

Sequential Sampling Plan for Tenuipalpus heveae Baker (Acari: Tenuipalpidae) on Rubber Tree

The objective of the present study was to develop a sequential sampling plan for the decision-making process to control Tenuipalpus heveae Baker (Acari: Tenuipalpidae), an important pest of the rubber tree crop. The experimental area was represented by 1,000 plants of the RRIM 600 clone divided in 100 plots with 10 plants each. Leaves were collected and the number of mites determined under laboratory conditions. The sequential sampling plan was developed in accordance with the Sequential Test Likelihood Ratio. The value 0.10 was pre-established for α and β representing type I and type II errors, respectively. The level of control adopted was six mites per 12 cm2. The operating characteristic curve and the curve of maximum expected sample were determined. Two lines were generated: the upper one, when the condition for chemical control is recommended (S1 = 23.3080 + 2.1972); and the lower, when chemical control is not recommended (S0 = -23.3080 + 2.1972). Sample size for the decision-making process to control T. heveae requires 6 to 18 plants. © 2013 Sociedade Entomológica do Brasil.

Interações de aranhas (Araneae) e artrópodes-praga (Acari e Hemiptera) em cultivos comerciais de seringueira (Hevea brasiliensis) no Noroeste do Estado de São Paulo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influência da vegetação nativa de Mata Atlântica sobre a ocorrência e distribuição de ácaros (Acari) da seringueira (Hevea brasiliensis Muell Arg.) no estado da Bahia

Pós-graduação em Biologia Animal - IBILCE

Adaptabilidade e estabilidade de progênies de Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell. - Arg. em três diferentes regiões do estado de São Paulo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Distribuição espacial e plano de amostragem seqüencial de ácaros fitófagos na cultura da seringueira [Hevea brasiliensis (Wild. Ex Adr. de Juss.) Müell.Arg.]

Pós-graduação em Agronomia - FEIS

Influência da qualidade das lâminas no desempenho físico-mecânico de painéis compensados de Hevea brasiliensis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Parasitismo de ovos de Leptopharsa heveae Drake & Poor, 1935 (Hemiptera: Tingidae) em seringueira (Hevea brasiliensis Müell. Arg.) no Estado do Mato Grosso

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Community structure of mites (Arachnida: Acari) in six rubber tree clones

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Performance of different rubber tree clones against South American leaf blight (Microcyclus ulei)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Phytoseiidae (Acari: Mesostigmata) from rubber tree crops in the State of Bahia, Brazil, with description of two new species

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Diversidade e sazonalidade de ácaros (Acari) em seringal (Hevea brasiliensis, Muell. Arg.) no Noroeste do Estado de São Paulo

Brazilian southeastern region has soil and climate conditions suitable for the growing of rubber trees, and most part of national yield arises from São Paulo State. The aims proposed for this work were to determine the diversity, the richness and the seasonal occurrence of mites found in a rubber tree crop in a triennial survey with monthly samplings, as well as to estimate the populational density of the major phytophagous species. This study found 74,407 mites from 26 species belonging to 10 families. The phytophagous and predators represented 95.4% and 3.9% of the total abundance, respectively. Twelve species were rare, six accessories and eight constant. The families Phytoseiidae and Tydeidae had the greatest richness (five and four species, respectively). The most numerous species was Calacarus heveae Feres (50,573), with great abundance at the end of rainy season until the beginning of dry season. Among predators, the most abundant were Zetzellia quasagistemas Hernandes & Feres (1,345), Pronematus sp. (455), Zetzellia agistzellia Hernandes & Feres (409) and Euseius citrifolius Denmark & Muma (243). C. heveae had greatest densities on March and April 2003, and Lorryia formosa Cooreman and Tenuipalpus heveae Baker on March and May 2001, respectively. Many stigmaeids were observed in association with colonies of L. formosa preying their eggs and immatures.

Diversidade e sazonalidade de ácaros (Acari) em seringal (Hevea brasiliensis, Muell. Arg.) no Noroeste do Estado de São Paulo

A Região Sudeste do Brasil apresenta aspectos edafo-climáticos favoráveis para o plantio e desenvolvimento da seringueira, sendo o estado de São Paulo o maior produtor nacional de látex. Este trabalho teve como objetivos determinar, através de coletas mensais durante três anos de estudo, a diversidade, a riqueza de espécies e a sua sazonalidade, bem como realizar estimativas de densidade populacional das principais espécies de ácaros presentes nas folhas. Todos os ácaros foram montados em lâminas de microscopia, totalizando 74.407 indivíduos, de 26 espécies pertencentes a 10 famílias. Os fitófagos representaram 95,4% do total de indivíduos coletados e os predadores 3,9%. Doze espécies foram consideradas acidentais, seis foram acessórias e oito constantes. Apresentaram maior número de espécies as famílias Phytoseiidae (cinco) e Tydeidae (quatro). A espécie mais abundante foi Calacarus heveae Feres (50.573), com maior abundância nos meses correspondentes ao término da estação chuvosa e início da estação seca na região. Dentre os predadores, a mais abundante foi Zetzellia quasagistemas Hernandes & Feres (1.345), seguida por Pronematus sp. (455), Zetzellia agistzellia Hernandes & Feres (409) e Euseius citrifolius Denmark & Muma (243). C. heveae apresentou maior densidade populacional em março e abril de 2003, e Lorryia formosa Cooreman e Tenuipalpus heveae Baker em março e maio de 2001, respectivamente. Muitos estigmeídeos foram observados associados a agrupamentos de L. formosa predando seus ovos e estágios imaturos.