RESUMO
Fruit processing waste, such as kernels (endocarp + seed) of avocado [Persea americana Mill. (Lauraceae)], could be used as raw material in the preparation of botanical insecticides. In light of this potential, this study assessed the insecticidal action of extracts and fractions from kernels of two avocado cultivars (Breda and Margarida) on Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) biotype B, an important pest species in tropical conditions. Ethanolic and aqueous extracts prepared from kernels of P. americana, regardless of the plant cultivar used, caused promising insecticidal activity to whitefly nymphs. Based on yield in crude extracts [10.32 and 9.85% (w/w), respectively, for cultivars Breda and Margarida], on the bioassay results with crude extracts and on the chemical profiles, the ethanolic extract of kernels of P. americana cv. Breda was chose for the continuation of the study. Thus, the ethanolic extract of kernels of cv. Breda (LC50 = 197.84 ppm and LC90 = 567.19 ppm) was selected and subjected to fractionation by the liquid-liquid partition technique. The hexane and dichloromethane fractions of this extract caused significant mortality of nymphs. The analysis using the ultraviolet (UV) and hydrogen nuclear magnetic resonance (1H NMR) showed the presence of long-chain aliphatic compounds (alkanols or acetogenins of Lauraceae), alkylfurans (or avocadofurans), and unsaturated fatty acids in these fractions, which are possibly related to bioactivity observed in B. tabaci, besides saccharides. The results show that kernels of P. americana are promising sources of compounds with insecticidal action for the control of B. tabaci biotype B, a great opportunity to transform environmental problems into eco-friendly solutions to agriculture.
Assuntos
Hemípteros , Inseticidas , Persea , Animais , Dose Letal Mediana , NinfaRESUMO
For more than four decades, the presence of the whitefly Bemisia tabaci Gennadius complex as a pest and transmitter of begomoviral diseases has been one of the most important phytopathological events in cultivated species worldwide. In addition, the number of whitefly species, as well as the viruses they transmit, has been increasing over time. In the state of Baja California Sur (BCS), Mexico, the diversity of B. tabaci has been delimited to MEAM1 and NW species, affecting mainly tomato, pepper, and squash. However, the relationship of these species with the dispersion of the begomoviruses previously detected in the study area is still unknown. In a 5-yr study (2012-2016), these species of whiteflies and begomoviruses were identified. Moreover, the recurrence, seasonal distribution, and impact they have on the spread of the begomoviral diseases were assessed. The identification of whiteflies was done targeting the mtCOI by PCR-DNA barcoding assay. For begomoviruses identification, a set of degenerate and specific primers targeting the IR region and CP gene were used. To determine seasonal abundance, monitoring was performed every 15 d by means of yellow traps. The MEAM1 species in all localities was observed with the highest peak population (>10 whiteflies/trap) from March to April. The guidelines for naming begomovirus species for the International Committee on Taxonomy of Viruses (ICTV) establish that the names when they are preceded by the acronym the whole name is in lowercase, not italicized (e.g. bean golden mosaic virus (BGMV)); when the name goes alone without the acronym then its capitalizes the first letter (e.g. Bean golden mosaic virus) and when these are referred to in a taxonomic sense they are italicized and the first letter is capitalized (e.g. Bean golden mosaic virus). This study provides details of the distribution and occurrence of MEAM1 species and diversity of begomoviruses that could be useful in disease management in BCS and worldwide.
Assuntos
Hemípteros , Solanum lycopersicum , Animais , Incidência , México , Estações do AnoRESUMO
The determination of the spatial distribution of a pest is the first step in the establishment of a sampling plan, as sampling methods are contingent upon the type of spatial distribution of the specific pest studied, varying according to the number and size of samples in the area. This work aimed to study the spatial distribution of soybean plants infested with Bemisia tabaci, under field conditions, through the determination of the aggregation indices and the chi-square test of fitness to the main types of theoretical frequency distributions. The average percentage of whitefly (B. tabaci) infestation increasing after the V1 stage, reaching the maximum infestation of 60.3% in the R1 stage. At the R2 stage, the percentage of infestation ranged from 20 to 40%. According to the models of theoretical distributions studied, the Poisson distribution best defines the distribution of the whitefly.(AU)
A determinação do arranjo espacial da praga torna-se o primeiro passo para o estabelecimento de um plano de amostragem, pois, conforme o tipo de distribuição espacial da praga específica estudada, será necessário utilizar diferentes métodos de amostragem, variando o número e o tamanho da amostra na área. O presente trabalho objetivou estudar a distribuição espacial das plantas infestadas por Bemisia tabaci em condições de campo, na cultura da soja, por meio da determinação dos índices de agregação e dos testes de qui-quadrado de aderência para os principais tipos de distribuições teóricas de frequência. Os resultados mostraram que a porcentagem média de infestação da mosca-branca (B. tabaci) foi aumentando a partir do estádio V1, atingindo a máxima infestação de 60,3% no estádio R1. A partir do estádio R2, a porcentagem de infestação variou entre 20% e 40%. Os modelos de distribuições teóricas estudados indicam que o modelo poisson é o que melhor define a distribuição da mosca-branca.(AU)
Assuntos
Glycine max , Pragas da Agricultura , Hemípteros , DemografiaRESUMO
The determination of the spatial distribution of a pest is the first step in the establishment of a sampling plan, as sampling methods are contingent upon the type of spatial distribution of the specific pest studied, varying according to the number and size of samples in the area. This work aimed to study the spatial distribution of soybean plants infested with Bemisia tabaci, under field conditions, through the determination of the aggregation indices and the chi-square test of fitness to the main types of theoretical frequency distributions. The average percentage of whitefly (B. tabaci) infestation increasing after the V1 stage, reaching the maximum infestation of 60.3% in the R1 stage. At the R2 stage, the percentage of infestation ranged from 20 to 40%. According to the models of theoretical distributions studied, the Poisson distribution best defines the distribution of the whitefly.(AU)
A determinação do arranjo espacial da praga torna-se o primeiro passo para o estabelecimento de um plano de amostragem, pois, conforme o tipo de distribuição espacial da praga específica estudada, será necessário utilizar diferentes métodos de amostragem, variando o número e o tamanho da amostra na área. O presente trabalho objetivou estudar a distribuição espacial das plantas infestadas por Bemisia tabaci em condições de campo, na cultura da soja, por meio da determinação dos índices de agregação e dos testes de qui-quadrado de aderência para os principais tipos de distribuições teóricas de frequência. Os resultados mostraram que a porcentagem média de infestação da mosca-branca (B. tabaci) foi aumentando a partir do estádio V1, atingindo a máxima infestação de 60,3% no estádio R1. A partir do estádio R2, a porcentagem de infestação variou entre 20% e 40%. Os modelos de distribuições teóricas estudados indicam que o modelo poisson é o que melhor define a distribuição da mosca-branca.(AU)
Assuntos
Glycine max , Pragas da Agricultura , Hemípteros , Características de ResidênciaRESUMO
The whitefly (Bemisia tabaci) causes damage in the soybean crop by sucking the plant sap, transmission of viruses and promoting sooty mold that affect the growing and the soybean production. The goal of this work was to evaluate the direct damage of the whitefly, and the vertical nymph distribution, on soybean cultivars under greenhouse conditions. The experimental design was randomized blocks with 10 cultivars in a 10 x 2 factorial scheme (infestation and without infestation) and 4 replications. Counts were made of the number of eggs and nymphs in the upper, middle and lower third of the plants. The productive indices were: number of pods per plant and grains per pod, weight of 100 grains, and weight of 2 plants. The data were submitted to variance analysis and F test (; 0.05), and the means were compared by Tukey test at 5% probability, obtaining the least significant difference between treatments. The cultivars were not affected by the B. tabaci attack at the infestations levels registered. CD 219 RR was the cultivar most infested by the whitefly nymphs. For better efficiency and use of time in the evaluations, in greenhouse studies it is suggested that they be carried out in the upper and middle thirds of the soybean plants.(AU)
A mosca-branca Bemisia tabaci causa danos em plantas de soja em decorrência da sucção de seiva, transmissão de vírus e favorecimento da fumagina, que afetam o desenvolvimento e a produção da cultura. O objetivo deste trabalho foi avaliar os danos diretos da mosca-branca e a distribuição vertical de ninfas em cultivares de soja em condições de casa de vegetação. O delineamento experimental foi de blocos ao acaso, com 10 cultivares no esquema fatorial 10 x 2 (com e sem infestação) e 4 repetições. Contabilizou-se o número de ovos e ninfas em todos os folíolos e, separadamente, em um folíolo do terços superior, médio e inferior das plantas Os índices de produtividade analisados foram: número de vagens por planta e de grãos por vagem, massa de 100 grãos e massa total de duas plantas. Os dados foram submetidos à análise de variância e ao teste F (; 0,05) e as médias comparadas pelo teste de Tukey ao nível de 5% de probabilidade, obtendo-se as diferenças mínimas significativas entre os tratamentos. As cultivares estudadas não foram afetadas pelo ataque de B. tabaci nos níveis de infestação registrados. CD 219 RR foi o cultivar mais infestada por ninfas de mosca-branca. Para melhorar a eficiência e o uso de tempo nas avaliações, em estudos em casa de vegetação, indica-se que estas sejam realizadas nos terços superior e médio das plantas.(AU)
Assuntos
Dípteros , Glycine max , Resistência à DoençaRESUMO
The whitefly (Bemisia tabaci) causes damage in the soybean crop by sucking the plant sap, transmission of viruses and promoting sooty mold that affect the growing and the soybean production. The goal of this work was to evaluate the direct damage of the whitefly, and the vertical nymph distribution, on soybean cultivars under greenhouse conditions. The experimental design was randomized blocks with 10 cultivars in a 10 x 2 factorial scheme (infestation and without infestation) and 4 replications. Counts were made of the number of eggs and nymphs in the upper, middle and lower third of the plants. The productive indices were: number of pods per plant and grains per pod, weight of 100 grains, and weight of 2 plants. The data were submitted to variance analysis and F test (; 0.05), and the means were compared by Tukey test at 5% probability, obtaining the least significant difference between treatments. The cultivars were not affected by the B. tabaci attack at the infestations levels registered. CD 219 RR was the cultivar most infested by the whitefly nymphs. For better efficiency and use of time in the evaluations, in greenhouse studies it is suggested that they be carried out in the upper and middle thirds of the soybean plants.
A mosca-branca Bemisia tabaci causa danos em plantas de soja em decorrência da sucção de seiva, transmissão de vírus e favorecimento da fumagina, que afetam o desenvolvimento e a produção da cultura. O objetivo deste trabalho foi avaliar os danos diretos da mosca-branca e a distribuição vertical de ninfas em cultivares de soja em condições de casa de vegetação. O delineamento experimental foi de blocos ao acaso, com 10 cultivares no esquema fatorial 10 x 2 (com e sem infestação) e 4 repetições. Contabilizou-se o número de ovos e ninfas em todos os folíolos e, separadamente, em um folíolo do terços superior, médio e inferior das plantas Os índices de produtividade analisados foram: número de vagens por planta e de grãos por vagem, massa de 100 grãos e massa total de duas plantas. Os dados foram submetidos à análise de variância e ao teste F (; 0,05) e as médias comparadas pelo teste de Tukey ao nível de 5% de probabilidade, obtendo-se as diferenças mínimas significativas entre os tratamentos. As cultivares estudadas não foram afetadas pelo ataque de B. tabaci nos níveis de infestação registrados. CD 219 RR foi o cultivar mais infestada por ninfas de mosca-branca. Para melhorar a eficiência e o uso de tempo nas avaliações, em estudos em casa de vegetação, indica-se que estas sejam realizadas nos terços superior e médio das plantas.
Assuntos
Dípteros , Resistência à Doença , Glycine maxRESUMO
Bemisia tabaci (Genn.) represents a complex of cryptic species that causes losses of many valuable crops. Even though there are differences in their ability to colonize hosts, transmit phytovirus and develop resistance to insecticides, the genetic differentiation of the insect populations is important for the adoption of control measures. Therefore, the genetic diversity of B. tabaci populations in economically important crops in Brazilian locations was characterized through a microsatellite analysis. Eight microsatellite markers were used for the analysis of eight populations, three in Solanum tuberosum (States of São Paulo, Minas Gerais and Bahia), two in Glycine max (States of São Paulo and Mato Grosso), one in Phaseolus vulgaris and Brassica oleracea var. acephala (States of São Paulo and Distrito Federal, respectively) and a cabbage population from Florida (USA). The number of alleles varied between two and 13 and the average value of F ST was 0.13. The population occurring in beans was genetically different, suggesting that the excessive use of insecticide or the host itself may have caused the modification of its allele frequency. The American population presented a large diversity and small differentiation compared to the Brazilian populations, especially from the Southeast, supporting the hypothesis that the B biotype was probably introduced into Brazil by the trade of plant material between the USA and the State of São Paulo. The genetic diversity found within and among the populations is geographically structured, and the insects from the central region of Brazil had superior genetic divergence when compared to the others Brazilian locations.
RESUMO
Bemisia tabaci (Genn.) represents a complex of cryptic species that causes losses of many valuable crops. Even though there are differences in their ability to colonize hosts, transmit phytovirus and develop resistance to insecticides, the genetic differentiation of the insect populations is important for the adoption of control measures. Therefore, the genetic diversity of B. tabaci populations in economically important crops in Brazilian locations was characterized through a microsatellite analysis. Eight microsatellite markers were used for the analysis of eight populations, three in Solanum tuberosum (States of São Paulo, Minas Gerais and Bahia), two in Glycine max (States of São Paulo and Mato Grosso), one in Phaseolus vulgaris and Brassica oleracea var. acephala (States of São Paulo and Distrito Federal, respectively) and a cabbage population from Florida (USA). The number of alleles varied between two and 13 and the average value of F ST was 0.13. The population occurring in beans was genetically different, suggesting that the excessive use of insecticide or the host itself may have caused the modification of its allele frequency. The American population presented a large diversity and small differentiation compared to the Brazilian populations, especially from the Southeast, supporting the hypothesis that the B biotype was probably introduced into Brazil by the trade of plant material between the USA and the State of São Paulo. The genetic diversity found within and among the populations is geographically structured, and the insects from the central region of Brazil had superior genetic divergence when compared to the others Brazilian locations.
RESUMO
O monitoramento da suscetibilidade de pragas a praguicidas é essencial para programas de manejo da resistência. O objetivo deste trabalho foi verificar a variabilidade genética de populações de Bemisia tabaci (Gennadius), oriundas de diferentes áreas agrícolas, quanto a suscetibilidade a inseticidas no Brasil, por meio de dois testes diferentes. Quatro populações de mosca-branca foram testadas em relação a uma população suscetível de referência (SusIAC); duas oriundas de Goiás (GO-1 e GO-2) e outras duas da Bahia (BA-1 e BA-2). Uma técnica de bioensaio do tipo contato residual foi empregada para realização dos testes: 1) teste diagnóstico da resistência; e 2) teste para obtenção das linhas de suscetibilidade das populações. Os produtos utilizados foram acetamipride, imidaclopride, tiametoxam, clorpirifós e endosulfam. Utilizaram-se insetos adultos não separados por sexo e nem por idade nos testes. As avaliações foram realizadas em 24h, para o teste com endosulfam, e em 48h, para os demais produtos. Ambos os testes revelaram variabilidade genética quanto à suscetibilidade de mosca-branca aos inseticidas. No entanto, a discriminação entre as populações de B. tabaci foi mais evidente com o uso de testes diagnósticos. A população GO-2 foi significativamente menos suscetível aos produtos testados que a SusIAC, principalmente em relação aos neonicotinóides. A situação mais crítica de resistência de mosca-branca foi com tiametoxam, seguida pelo imidaclopride.
Monitoring the susceptibility of a pest population to pesticides is essential for resistance management programs. The objective of this research was to evaluate the genetic variability in pesticide susceptibility in populations of Bemisia tabaci (Gennadius) collected from different Brazilian agricultural regions through the use of two different tests. Four whitefly populations, two from Goiás state (GO-1 and GO-2) e two from Bahia state (BA-1 and BA-2), were tested against a susceptible reference one (SusIAC). A residual contact bioassay was used to evaluate the pesticide susceptibility of each population by using diagnostic concentration bioassays and by estimating the baseline susceptibility data to each one of the tested insecticides, acetamiprid, imidacloprid, thiamethoxam, chlorpyrifos and endosulfan. Adult insects of unknown age and sex were tested. Evaluations were performed after 24h for endosulfan and 48h for the other chemicals. Both procedures showed significant differences in the susceptibility to the pesticides among B. tabaci populations. However, the discrimination among B. tabaci populations was more evident with the use of diagnosis tests. The population GO-2 was significantly less susceptible to the tested pesticides than SusIAC, mainly to neonicotinoids. The most critical resistance situation of B. tabaci was detected to thiamethoxam, followed by imidacloprid.
Assuntos
Animais , Hemípteros/efeitos dos fármacos , Hemípteros/genética , Inseticidas/farmacologia , BrasilRESUMO
Em fevereiro e outubro de 1998, na área experimental da Fazenda de Ensino e Pesquisa da UNESP no município de Selvíria-MS (latitude 20° 22' S, longitude 51° 22' W, altitude 335 m), foi constatada a presença de mosca branca em mamoeiro cultivar Baixinho de Santa Amália, plantado no interior de um telado com malha de 2 x 2 mm. Essa área fazia parte de um experimento visando determinar o efeito do cultivo em ambiente protegido sobre o desenvolvimento das plantas, a produção de frutos e a ocorrência do mosaico do mamoeiro. Nas duas ocasiões os insetos foram enviados ao Centro de Recursos Genéticos e Biotecnologia (CENARGEN) da EMBRAPA para identificação. Na primeira infestação o material foi identificado como Trialeurodes sp. e na infestação de outubro como Bemisia tabaci biótipo B . Nos dois casos havia grande quantidade de ninfas nas folhas maduras e de adultos nas folhas novas. Para Trialeurodes sp. foi realizada uma contagem de ninfas em dezoito folhas, em cinco áreas de 1 cm² por folha, distribuídas ao acaso, encontrando-se a média de 7,6 ninfas por cm². Como conseqüência da presença das duas espécies, o único dano observado foi um intenso desenvolvimento de fumagina recobrindo completamente a superfície das folhas, que acabaram por secar e cair. A infestação de B. tabaci biótipo B foi controlada pela presença de larvas e adultos do coccinelídeo Delphastus pusillus (LeConte) que alimentavam-se vorazmente das ninfas presentes.
We report the presence of whitefly species at the Experimental Farm of UNESP, located in Selvíria, state of Mato Grosso do Sul, Brazil ( 20°22' latitude S, 51°22' longitude W, altitude 335 m), in February and October 1998. These insects were found on papaya trees cultivar Baixinho de Santa Amália, grown under screened conditions (2 mm x 2 mm mash). The goal of the original experiment was to determine the effect of growing the cultivar under a protected environment on the development of the trees, fruit production and incidence of the "papaya ringspot virus". Whitefly specimens were sent to the Center of Genetic Resources and Biotechnology (CENARGEN) of EMBRAPA, for identification. The specimens collected in February were identified as Trialeurodes sp. and those collected in October were recognized as Bemisia tabaci biotype B. In both ocasions there were great numbers of nymphs on mature leaves and of adults on young leaves. We counted the number of Trialeurodes nymphs in eighteen leaves, in five areas of 1 cm² per leaf, distributed at random, where we found an average of 7.6 nymphs/cm². The only damage associated with the presence of whitefly of both species was the intense development of `sooty molds', covering completely the leaves, which wilted and fell. The infestation of B. tabaci biotype B was controlled by larvae and adults of the coccinellid Delphastus pusillus (LeConte), which fed avidly on the whitefly nymphs.