Biocontrol Potential of Neoseiulus californicus (Mesostigmata : Phytoseiidae) Against Oligonychus punicae (Acari: Tetranychidae) in Avocado.

Oligonychus punicae (Hirst) (Trombidiformes: Tetranychidae) is a common pest in Mexican avocado orchards. Neoseiulus californicus (McGregor) (Mesostigmata: Phytoseiidae) is frequently found associated with avocado orchards in Mexico and may be an important aid for controlling O. punicae. Given the lack of information in the scientific literature, this study evaluated the predation and oviposition of N. californicus when fed O. punicae at different developmental stages in a no-choice experiment. We also assessed fluctuations in the population size of O. punicae and N. californicus in commercial avocado orchards; correlations among mite density and air temperature, humidity, and precipitation in commercial avocado orchards; and the correlations between prey and predator populations. The no-choice test revealed that N. californicus adult females fed on O. punicae of all developmental stages, with higher levels of predation being recorded for eggs, followed by larvae. The highest oviposition values of N. californicus females were observed when females were fed O. punicae eggs. In orchards, the populations of both mites increased between February and June. The populations peaked during the warmest months of the year, with O. punicae populations peaking between June and July and N. californicus peaking in August. In addition, the population size of N. californicus was significantly and positively correlated with rainfall, air temperature, and the population densities of O. punicae. Meanwhile, O. punicae population size was positively correlated with air temperature, and the population of its predator N. californicus.

Fumonisin Production by Fusarium verticillioides in Maize Genotypes Cultivated in Different Environments.

Fumonisins are mycotoxins (MTs) produced mainly by the fungus Fusarium verticillioides, the main pathogens of maize which cause ear rot. The aim of this work was to evaluate some factors that may lead to high fumonisin production by F. verticillioides in maize grains, correlating the pathogen inoculation method with different genotypes grown in four Brazilian states. Experiments were conducted in 2015-2016 in maize crops from experimental maize fields located in four distinct states of Brazil. Results showed that contamination by fumonisin mycotoxins occurred even on symptomatic or asymptomatic grains. In all municipalities, the samples showed levels of fumonisin B1 that were higher than would be tolerable for the human consumption of corn products (the current tolerance limit for fumonisin is 1.5 µg g-1). High severity of grains infected with F. verticillioides does not always show high concentrations of fumonisins. Environments with higher temperatures may influence the production of high concentrations of fumonisin in maize hybrids. Spray inoculation methods and inoculation at the center of spikes did not influence fumonisin concentrations. Results showed that the hybrids P3630H, P32R48 and P3250 presented higher disease severity, as well as higher mycotoxin levels in the studied locations with higher temperatures.

Morphology and infection process of Olivea neotectonae in teak leaves / Morfologia e processo de infecção de Olivea neotectonae em folhas de teca

Rust, caused by the biotrophic fungus Olivea neotectonae, stands out as an important disease in teak plantations in Brazil. Considering the current importance of this rust and the need to obtain additional basic information about its causal agent to better disease management, the present study aimed to analyze the morphology of O. neotectonae using light microscopy and demonstrate the infection process in teak leaves using scanning electron microscopy techniques (SEM). The morphological characteristics observed using light microscopy were similar to those described in the literature for this species. SEM revealed that the infection structures of the pathogen penetrated the teak leaf through the stomata complex. This study provides the first microscopic evidence of the infection process of Olivea neotectonae in leaves of teak plants.(AU)

A ferrugem, causada pelo fungo biotrófico Olivea neotectonae, destaca-se como uma doença importante nas plantações de teca no Brasil. Considerando a importância atual dessa ferrugem e a necessidade de obter informações básicas adicionais sobre seu agente causal para melhor manejo da doença, o presente estudo teve como objetivo analisar a morfologia da O. neotectonae utilizando microscopia de luz e demonstrar o processo de infecção em folhas de teca por meio de técnicas de microscopia eletrônica de varredura (MEV). As características morfológicas observadas em microscopia de luz foram semelhantes às descritas na literatura para essa espécie. A MEV revelou que as estruturas de infecção do patógeno penetraram na folha de teca através do complexo estomático. Este estudo fornece a primeira evidência microscópica do processo de infecção de Olivea neotectonae em folhas de plantas de teca.(AU)

Spatial-temporal distribution of phytophagous and predatory mites in the canopy of Jatropha curcas L / Distribuição espaço-temporal de ácaros fitófagos e predadores no dossel de plantas de pinhão-manso

The aim of the present study was to evaluate the spatial-temporal distribution of phytophagous and predatory mites in the canopy of Jatropha curcas L. Mite richness, diversity, and abundance were determined, and higher values were observed primarily in the top stratum. Mite population in J. curcas was higher during the rainy season. Phytophagous mites were mostly concentrated in the top stratum, and Brevipalpus sp. was the most abundant. Predatory mites from the family Phytoseiidae presented the highest richness and diversity, and Amblydromalus zannoui was the most abundant species. The present results indicate seasonal population dynamics for both predatory and phytophagous mites on J. curcas.(AU)

O presente estudo teve por objetivo avaliar a distribuição espaço-temporal de ácaros fitófagos e predadores no dossel de plantas de pinhão-manso. Parâmetros de riqueza, diversidade e abundância de ácaros foram determinados. Os resultados deste estudo demonstram que maiores valores de riqueza, diversidade e abundância de ácaros foram observados principalmente no estrato apical e que os níveis populacionais desses artrópodes em plantas de pinhão-manso são mais expressivos na estação chuvosa. Os ácaros fitófagos concentram-se distribuídos principalmente no estrato apical, sendo Brevipalpus sp. a espécie mais abundante. Ácaros predadores da família Phytoseiidae foram aqueles de maior riqueza e diversidade, sendo o ácaro predador Amblydromalus zannoui o mais abundante. Os resultados obtidos neste trabalho sugerem uma dinâmica sazonal tanto para populações de ácaros predadores quanto para ácaros fitófagos em pinhão-manso.(AU)

The Efficiency of Noni (Morinda citrifolia L.) Essential Oil on the Control of Leaf Spot Caused by Exserohilum turcicum in Maize Culture.

The objective of this work was to evaluate the efficiency of noni essential oil on the control of Exserohilum turcicum, a causative agent of Exserohilum spot in maize culture. In the sanitary test 400 seeds were incubated using the blotter test method. For the transmissibility test, the fragments of damaged leaves of seedlings were removed and put into a potato, dextrose and agar (PDA) culture environment. To verify the pathogenicity, Koch´s postulates were performed. In the phytotoxicity test different concentrations of noni oil were applied in maize seedlings. E. turcicum conidia were submitted to different concentrations of noni oil. In the preventive and curative tests noni essential oils were applied before and after the conidia inoculation, respectively. The results revealed the presence of fungi of the genres Aspergillus, Penicillium, Rhizopus, Fusarium, and Exserohilum in the maize seeds. The pathogenicity of E. turcicum and also the transmission of this fungus from the seeds to the maize seedlings was confirmed. The inhibition of conidia germination was proportional to the concentration increase. The preventive application of noni essential oil was the most efficient on the control of Exserohilum spot.

Avaliação in vitro de diferentes métodos de análises de fungitoxicidade de óleos essenciais / Evaluation in vitro of different methods of analysis fungitoxicity of essential oils

Os problemas ambientais causados por fungicidas sintéticos têm elevado as buscas por métodos alternativos de controle de doenças de plantas. Objetivou-se avaliar o efeito do óleo essencial de capim citronela, sobre o fungo Rhizoctonia solani, em diferentes métodos de avaliação de fungitoxicidade in vitro. Foi utilizado delineamento inteiramente casualizado em esquema fatorial com quatro repetições, onde os fatores foram compostos por quatro métodos de avaliação da fungitoxicidade in vitro do óleo essencial (óleo essencial diluído em Tween 80 (0,5%) e incorporado ao meio de cultura BDA (batata, dextrose e ágar) ainda fundente; óleo essencial diluído em Tween 80 (0,5%) e distribuído na superfície do BDA; óleo essencial diluído em Tween 80 (0,5%) e distribuído em papel filtro fixado na superfície interna da tampa da placa de Petri; óleo essencial puro e distribuído na superfície do meio de cultura; e testemunha) e por cinco épocas de avaliação (2, 4, 6, 8 e 10 dias de incubação). Foram utilizados 0,25µL mL-1 do óleo do capim citronela em todos os tratamentos. Dos tratamentos avaliados o uso do óleo puro distribuído na superfície do meio de cultura foi mais eficiente na redução do diâmetro micelial em todas as avaliações. Neste método a taxa de crescimento micelial foi de 9, 02 mm dia-1, atingindo na última época de avaliação 79,77 mm.

Environmental problems caused by synthetic fungicides have increased the search for alternative methods of control of plant diseases. The objective was to evaluate the effect of essential oil of citronella grass, on the fungus Rhizoctonia solani, in different methods of in vitro fungitoxicity. We used a randomized design in a factorial design with four replications, where the factors were composed of four methods for assessing the in vitro fungitoxicity of the essential oil of citronella grass (essential oil diluted in Tween 80 (0.5%) and embedded in the culture medium PDA (potato dextrose agar) still melting, essential oil diluted in Tween 80 (0.5%) and distributed on the surface of the PDA; oil essential diluted in Tween 80 (0.5%) and distributed on filter paper attached to the inner surface of the lid of the Petri dish, pure essential oil and distributed on the surface of the culture medium, and control) and five evaluation periods (2, 4, 6, 8 and 10 days of incubation). Was used 0.25µL mL-1 of citronella oil in all treatments. Of the treatments evaluated the use of pure oil distributed on the surface of the culture medium was more effective in reducing the mycelial diameter in all evaluations. In this method the rate of mycelial growth was 9,02 mm day-1, reaching in last evaluation 79,77 mm.

Reação fenotípica de genótipos de abóboras ao vírus da mancha anelar do mamoeiro, estirpe melancia (Pappaya ringspot virus, strain watermelon ­ PRSV-W) / Phenotypic reaction of Cucurbita spp. genotypes to Pappaya ringspot virus, watermelon strain ­ PRSV-W

O Pappaya ringspot vírus, estirpe melancia - PRSV-W, é a principal doença virótica das abóboras em condições tropicais. O trabalho objetivou avaliar a resistência fenotípica e o padrão de sintomas apresentados por genótipos de abóboras (Cucurbita spp.) ao PRSV-W. O experimento foi conduzido no delineamento inteiramente casualizado com quatro repetições e 10 plantas por parcela. Foram realizadas duas inoculações, a primeira na fase cotiledonar e a segunda cinco dias após a primeira. As plantas foram avaliadas quanto ao aparecimento de sintomas durante 30 dias, começando 10 dias após a segunda inoculação, através de uma escala de notas, em que: nota ­ 1: plantas com folhas sem sintomas de mosaico e; nota ­ 5: plantas com folhas apresentando mosaico intenso, com bolhosidade e presença de deformações foliares mais severas. Foram avaliados nove genótipos, dos quais três são regionais [ABTO#01 e ABTO#02 (C. maxima); ABTO#03 (C. moschata)]; e seis são cultivares comerciais [cv. Caserta (C. pepo); cvs. Menina Brasileira; Paulista; Baianinha; Jacarezinho (C. moschata); e o híbrido interespecífico Tetsukabuto ou Kabutiá (C. máxima x C. moschata)]. Também foram avaliadas progênies endogâmicas do acesso ABTO#01. Apenas o genótipo regional ABTO#01 não apresentou sintomas durante o período de avaliação, sendo considerado resistente. Todos os genótipos comerciais foram suscetíveis e os sintomas apresentados foram bolhosidades, mosaicos, estreitamento foliar e subdesenvolvimento. Todas as progênies endogâmicas oriundas do acesso ABTO#01 avaliadas foram resistentes ao PRSV-W e, portanto, constituem progênies promissoras para serem utilizadas em programas de melhoramento genético da abóbora para a região do Tocantins.

The Pappaya ringspot virus, watermelon strain - PRSV-W is the most important viral disease of Cucurbita spp. in the tropical conditions. The study evaluated the phenotypic resistance and the pattern of symptoms presented by the genotypes of Cucurbita spp. to PRSV-W. The experiment was conducted in completely randomized design with four replications. The plants were evaluated for symptoms 30 days after inoculation, using a scale where: Note - 1: plants with no symptoms of mosaic and; note - 5: plants with leaves showing mosaic intense with blistering and the presence of more severe leaf deformation. Nine genotypes were evaluated, three landraces [ABTO#01; ABTO#02 (C. maxima) e ABTO#03 (C. moschata) and six commercial cultivars [cv.Caserta (C. pepo); cvs. Menina Brasileira; Paulista; Baianinha; Jacarezinho (C. moschata) and the interspecific hybrid Tetsukabuto or Kabutiá (C. moschata x C. maximum)]. Inbred progenies from ABTO#01 were also evaluated. All commercial genotypes were susceptible and symptoms were blistering, mosaics, leaf narrowing and underdevelopment. The genotype ABTO#01 and their inbred progeny presented no virus symptoms during the evaluation period, being considered resistant and a promising genotype to be used in breeding programs of the Cucurbita spp. aiming resistance to PRSV-W.

Fat body morphology of Eriopis connexa (coleoptera, coccinelidae) in function of two alimentary sources

Joaninhas são eficazes predadores de artrópodes atuando diretamente sobre certas pragas e alimentando-se de parte ou de todo o corpo da presa. Dentre os coccinelídeos, Eriopis connexa possui uma posição de destaque no controle de pulgões. Os coccinelídeos por serem predadores generalistas, apresentam uma variabilidade na escolha de presas, alimentando-se também de ácaros. No Brasil, trabalhos realizados com E. connexa, apenas relatam a sua ocorrência, sendo assim este trabalho objetivou investigar a influência de duas fontes alimentares: pulgões e ácaros, na morfologia do corpo gorduroso de E. connexa. Os resultados mostraram que as células do corpo gorduroso dos indivíduos alimentados com pulgões apresentaram áreas mais de três vezes superiores (511 ± 98,7µm2) que as das células do corpo gorduroso de indivíduos alimentados com ácaros (162 ± 34,9µm2). Além disso, testes histoquímicos demonstraram que a quantidade de nutrientes estocados no corpo gorduroso também foi superior em indivíduos alimentados com pulgões.