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.

Controle biologico do percevejo-de-renda (Leptopharsa heveae Drake & Poor) em seringais de cultivo.

A mosca-de-renda ou percevejo-de-renda (Leptopharsa heveae - Hemiptera: Tingidae) e o mais importante inseto-praga da seringueira no Brasil. Essa praga de origem amazonica invadiu os seringais do Estado de Mato Grosso por volta de 1985 e, de 1992 a 1998, chegou aos seringais do Estado Sao Paulo e de Goias. Acredita-se que breve chegara aos Estados da Bahia, Espirito Santo e Minas Gerais. O principal agente disseminador desse inseto-praga entre estados e seringais tem sido os veiculos transportadores de coagulos e latex semiprocessado (GEB). O controle quimico dessa praga, alem de muito caro, coloca em risco os aplicadores e o meio ambiente. Em 1986, no Amazonas, o fungo Sporothrix insectorum foi constatado parasitando individuos do percevejo-de-renda. Com base nessa constatacao foram feitos alguns estudos em campo e laboratorio onde se determinaram a eficiencia biologica (capacidade do inimigo natural para infectar e destruir a praga) e a eficiencia tecnica (capacidade do inimigo natural para reduzir os danos causados na planta pela acao da praga). Os resultados desses testes evidenciaram o elevado potencial do S. insectorum para o controle do percevejode-renda. Imediatamente apos os testes, esse fungo foi enviado para os Estados de Mato Grosso, Acre, Rondonia, e mais recentemente para Sao Paulo e Goias onde vem sendo utilizado com o fungo Hirsutella verticillioides por diversos produtores e empresas. O fungo H. verticillioides, outro inimigo natural do percevejo-de-renda, isolado em 1990, na Guiana Francesa, vem sendo bem mais agressivo nos seringais da regiao Centro-Oeste e de Sao Paulo que o S. insectorum. Os resultados obtidos de avaliacoes efetuadas em alguns seringais de Goias, Mato Grosso e Sao Paulo indicam eficiencia biologica (porcentagem de insetos colonizados e fixados na folha por ambos os fungos em fevereiro), variando de 53% a 100%. Por outro lado, a eficiencia tecnica, medida pelo nivel de descoloracao da folha ou % de danos causados pela praga em fevereiro, tendo como referencia folhas nao atacadas, variou de 16% a 63%.

Virulência de Aphanocladium album (Preuss) Gams e Verticillium lecanii (Zimm.) Viégas (Deuteromycotina: Hyphomycetes) para o Percevejo-de-renda da seringueira, Leptopharsa heveae (Drake & Poor) (Hemiptera: Tingidae)

The lace bug, Leptopharsa heveae is an insect that causes serious damage on rubber trees. In laboratory condition, the strains of Verticillium lecanii (ARSEF 6430, 6431 e 6432) and Aphanocladium album (ARSEF 6433) were tested on third-and fifth-instar nymphs and adults of L. heveae to evaluate their virulence using 2.4 x 10(5) and 2.4 x 10(7) conidia/mL. The bioassays were carried out using Petri dishes whose inner bottoms were covered with damp filter papers. Each Petri dish contained five insects and one rubber tree leaflet. The plates were covered with PVC film to provide high relative humidity, maintained at 26 +/- 0.5 degrees C and a photophase of 14 hours. The Probit analysis was calculated from mortality date of insects killed by fungi. In the highest concentrations, ARSEF 6430 was more virulent for third instar nymphs, and the LT50 was 1.9 days. For the fifth instar, the strains ARSEF 6430, 6433 and 6432 showed similar virulence with LT50 of 2.6, 2.6 and 3.2 days, respectively. For adults, ARSEF 6431 was the most virulent strain with the LT50 recorded at 2.0 days. The smallest concentration did not always cause more than 50% mortality.

Biologia de Leptopharsa heveae Drake & Poor (Heteroptera: Tingidae) e a relação de suas exigências térmicas com a flutuação populacional em seringueira

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

Parasitismo de Erythmelus tingitiphagus (Soares) (Hymenoptera: Mymaridae) em ovos de Leptopharsa heveae Drake & Poor (Hemiptera: Tingidae), em plantios de seringueira (Hevea brasiliensis Müell. Arg.)

The rubber tree lace bug, Leptopharsa heveae Drake & Poor occurs in high populations in rubber tree plantations and it is a limiting factor in rubber production due to the loss of photosynthetic tissue. The control of the pest has been made mainly with chemical products, which cause environmental contamination. The alternative would be the use of biological control agents, however, information about L. heveae natural enemies are scarce. The parasitoid Erythmelus tingitiphagus (Soares) parasitize eggs of the rubber tree lace bug. The aim of this study was to verify the occurrence of E. tingitiphagus in plantations of several rubber tree clones, located in Itiquira town, Mato Grosso State. The plant leaflets of the clones RRIM 600, PR 255, GT 1, PB 235 and PB 217 were collected weekly from October 2005 to February 2006. Parasitism was recorded during the entire study period. The parasitism rate of L. heveae eggs in the different clones ranged from 16.8 to 20.6%.

Distribuição de Leptopharsa heveae em seringal no Estado de São Paulo

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Distribuição espacial de Tenuipalpus heveae Baker (Acari: Tenuipalpidae) na cultura da seringueira

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Biological cycle of Tenuipalpus heveae Baker (Acari, Tenuipalpidae) on leaflets of three rubber tree clones

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Seleção de isolados de fungos entomopatogênicos para o controle de Leptopharsa heveae (Hemiptera: Heteroptera, Tingidae)

Foram analisados vinte e sete isolados de fungos entomopatogênicos procedentes de diversos hospedeiros e regiões. A produção de conídios dos patógenos foi efetuada em placas de Petri contendo meio de cultura BDA. Insetos de terceiro instar de Leptopharsa heveae foram inoculados com uma suspensão fúngica na concentração de 1 x 10(9) conídios/mL. Avaliações de mortalidade confirmada foram efetuadas a cada dois dias e evidenciaram grande variação de virulência, sendo o isolado 1.189, de Metarhizium anisopliae, o mais virulento. Os cinco melhores isolados, mais os dois tidos como padrão por empresas do setor de heveicultura, foram então submetidos aos testes de produção. Para tanto, pré-matrizes em placas de Petri contendo meio de cultura BDA foram preparadas. A partir destas placas, matrizes contendo arroz como meio de cultura foram inoculadas com suspensão de conídios originária das pré-matrizes na concentração de 5 x 10(7) conídios/mL. Concluído o desenvolvimento dos patógenos nas matrizes, sacos de polipropileno contendo canjica de milho como meio de cultura foram inoculados com 40 mL da suspensão obtida a partir das matrizes. Após 15 dias de incubação, o conteúdo das sacolas foi avaliado quanto à produção e viabilidade de conídios. O isolado 1200, de Isaria fumosorosea, apresentou os melhores resultados de rendimento total e taxa de viabilidade e o isolado E9 de Metarhizium anisopliae foi o mais virulento ao percevejo de renda.

Nonpreference of the lace bug Leptopharsa heveae Drake & Poor (Heteroptera: Tingidae) for rubber tree clones

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Population dynamics of Leptopharsa heveae (Hemiptera: Tingidae) and Erythmelus tingitiphagus (Hymenoptera: Mymaridae) in rubber tree plants

The tingid Leptopharsa heveae, known as the lace bug, occurs in large populations in rubber tree plantations, limiting the production of latex due to losses of photosynthetic area and weakening of the infested trees. The alternative for the use of insecticides would be the release of biological control agents, but little is known about the natural enemies of L. heveae. The parasitoid Erythmelus tingitiphagus parasitizes eggs of the lace bug in rubber tree plantations. The knowledge of the population dynamics and the peak of occurrence of economically important insect species and their natural enemies are indispensable requirements for the establishment of efficient and rational control strategies. The objective of this work was to study the population dynamics of L. heveae and E. tingitiphagus in rubber tree plantations in the county of Itiquira, MT, Brazil. Mature folioles were collected weekly from the lower stratum of the canopy of the tree clones RRIM 600, PR 255, GT 1, PB 235 and PB 217, from August/2005 to February/2006. The parasitoid was observed during the whole study period. The population peaks of the populations of the L. heveae and E. tingitiphagus in the study area occurred at the end of October and beginning of November. This result demonstrates that measures for the control of L. heveae and population increase of E. tingitiphagus must be adopted before the peak population of this pest in cultivated rubber plantations.

Atividade predatória de Euseius citrifolius Denmark & Muma (Acari: Phytoseiidae) sobre Tenuipalpus heveae (Acari: Tenuipalpidae)

The rubber tree red false spider mite, Tenuipalpus heveae Baker, is an important pest of Hevea brasiliensis (Willd. ex. Adr. de Juss.) Muell. Arg. The phytoseiid mite Euseius citrifolius Dennmark & Muma has frequently been recorded on rubber tree crops. The objective of this work was to determine the predatory activity of E. citrifolius on the different life stages (egg, larva, nymph and adult) of T. heveae. The experiments were carried out in Petri dishes (9-cm diameter) containing a layer of wet cotton inside, onto which a disk of rubber tree leaf (2.5-cm diameter) was laid. The disks were taken from naturally infested leaves. Twenty specimens in the life stage that was to be tested were left on the disk and the others were eliminated; a predator life stage (larva, nymph or female) was obtained from a laboratory stock colony and put into each dish. For each tested life stage of E. citrifolius, 4 treatments (T. heveae life stages) and 20 replications were considered in a randomized block design. The observations were made after 24 hours for larvae and nymphs of the predator, and after 24, 48 and 72 hours for the females. E. citrifolius larvae and nymphs had a higher preference for T. heveae larvae followed by nymphs, eggs and adults. Within 72 hours, each predator female consumed 15.0 larvae, 14.5 nymphs, 7.4 adults or 2.2 eggs of T. heveae. It is concluded that E. citrifolius can feed on red false spider mites, the larva and nymph being the preferred stages.

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.

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.