Bemisia tabaci MED (Hemiptera: Aleyrodidae): Resistência de genótipos de tomateiro e bioatividade de óleos essenciais
Data
2022-04-08
Autores
Santos, Maria Clezia dos [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
O tomateiro, Solanum lycopersicum L. (Solanaceae), possui grande importância econômica para o Brasil, tanto pelo consumo in natura quanto para o processamento industrial. No entanto, sua produtividade é constantemente afetada por diversas espécies de insetos-praga. Nesse sentido, o avanço de Bemisia tabaci (Gennadius) MED (Hemiptera: Aleyrodidae) nas principais áreas de cultivo de tomateiro no Brasil é preocupante, em decorrência da elevada capacidade de infestação do inseto, além de importante vetor inúmeros vírus letais às plantas. Em adição, B. tabaci MED possui histórico de menor suscetibilidade a inseticidas em relação a B. tabaci MEAM1, exigindo maior atenção dos produtores. Assim, este trabalho teve como objetivo caracterizar a possível resistência por antixenose de genótipos de tomateiro de diversas origens frente a B. tabaci MED, além de avaliar os efeitos letais e subletais de óleos essenciais, bem como seus efeitos no comportamento alimentar do inseto por meio da técnica de Electrical Penetration Graph (EPG). Para os testes de resistência, foram realizados ensaios de preferência (infestação e oviposição) sem e com chance de escolha com adultos, além da avaliação de colonização por ninfas. Paralelamente, foram realizadas análises físicas (coloração) e morfológicas (tricomas) nas folhas de alguns genótipos selecionados, visando correlacionar com a resistência observada. Os genótipos LA 716, IAC 294, PI 127826, PI 134418 e PI 134417 expressaram elevados níveis de antixenose, enquanto Tainara, PI 126925 e LA 116 revelaram resistência moderada a B. tabaci MED. A densidade de tricomas glandulares foi negativamente correlacionada com o número de adultos, ovos/cm² e ninfas/cm² de B. tabaci MED. Por sua vez, a densidade de tricomas não glandulares e a maior inclinação dos tricomas estimularam a colonização da praga. A cor do substrato não foi correlacionada à resistência dos genótipos. Os óleos essenciais de Pelargonium graveolens (OE-PG, CL50=3,532 µl/mL), Eugenia uniflora (OE-EU, CL50=5,60 µl/mL), Piper callosum (OE-PC, CL50=8,36) e Vitex agnus-castus (OE-VAC, CL50=9,00 µl/mL), assim como o composto majoritário citronelol de OE-PG foram tóxicos a B. tabaci MED, sendo a menor CL50 estimada para o OE-PG dentre os óleos e compostos majoritário citronelol (CL50=4,21 µl/mL). Assim, base na razão de toxicidade, o OE-PG foi mais tóxico que OE-PC e OE-VAC a ninfas de mosca-branca. Em adição, o OE-PG apresentou efeito ovicida e adulticida, em condições de laboratório, e efeito ninficida, em condições semi-campo, com eficiência semelhante aos inseticidas comerciais. Nos ensaios de EPG, o inseticida ciantraniliprole e a CL25 de OE-PG afetaram as atividades estiletares da mosca-branca, reduzindo o número de caminhamentos, (onda C). Além disso, todos os tratamentos reduziram o número e a duração de ingestão de seiva do floema, (onda E2), em relação ao tratamento controle. A CL25 de OE-PG também afetou no aumentou a duração por inseto e a duração total na fase xilemática. Em síntese, os resultados deste estudo indicam que os genótipos LA 716, IAC 294, PI 127826, PI 134418 e PI 134417 apresentam elevados níveis de resistência por antixenose a B. tabaci MED, e suas caraterísticas físico-morfológicas são determinantes para a expressão de resistência. Além disso, o OE-PG causa efeitos tóxicos e subletais (alimentação) à mosca-branca, indicando seu potencial para o manejo alternativo de B. tabaci MED em tomateiro.
Tomato, Solanum lycopersicum L. (Solanaceae), has great economic importance for Brazil, both for fresh consumption and for industrial processing. However, its productivity is constantly affected by several insect pest species. In this sense, the advance of Bemisia tabaci (Gennadius) MED (Hemiptera: Aleyrodidae) in the main areas of tomato cultivation in Brazil is worrying, due to the high capacity of infestation of the insect, as well as an important vector for numerous lethal viruses to plants. In addition, B. tabaci MED has a history of lower susceptibility to insecticides compared to B. tabaci MEAM1, requiring greater attention from producers. Thus, this work aimed to characterize the possible antixenosis resistance of tomato genotypes of different origins against B. tabaci MED, in addition to evaluating the lethal and sublethal effects of essential oils, as well as their effects on the insects feeding behavior through of the Electrical Penetration Graph (EPG) technique. For resistance tests, preference tests were performed (infestation and oviposition) with and without choice with adults, in addition to the evaluation of colonization by nymphs. At the same time, physical (staining) and morphological (trichomes) analyzes were carried out on the leaves of some selected genotypes, in order to correlate with the observed resistance. The genotypes LA 716, IAC 294, PI 127826, PI 134418 and PI 134417 expressed high levels of antixenosis, while Tainara, PI 126925 and LA 116 showed moderate resistance to B. tabaci MED. The density of glandular trichomes was negatively correlated with the number of adults, eggs/cm² and nymphs/cm² of B. tabaci MED. In turn, the density of non-glandular trichomes and the greater inclination of the trichomes stimulated the colonization of the pest. Substrate color was not correlated with genotype resistance. The essential oils of Pelargonium graveolens (EO-PG, LC50=3.532 µl/mL), Eugenia uniflora (EO-EU, LC50=5.60 µl/mL), Piper callosum (EO-PC, LC50=8.36) and Vitex agnus-castus (EO-VAC, LC50=9.00 µl/mL), as well as the major compound citronellol from OE-PG were toxic to B. tabaci MED. Being the lowest estimated LC50 for EO-PG among the oils and major compounds citronellol (LC50=4.21 µl/mL). Thus, based on the toxicity ratio, EO-PG was more toxic than EO-PC and EO-VAC to whitefly nymphs. In addition, EO-PG showed an ovicidal and adulticidal effect, under laboratory conditions, and a nymphicidal effect, under semi-field conditions, with efficiency similar to commercial insecticides. In the EPG assays, the insecticide cyantraniliprole and the LC25 of EO-PG affected the whitefly stylist activities, reducing the number of walks, (C wave). In addition, all treatments reduced the number and duration of phloem sap ingestion (E2 wave) compared to the control treatment. The LC25 of EO-PG also affected the increased duration per insect and the total duration in the xylem phase. In summary, the results of this study indicate that the genotypes LA 716, IAC 294, PI 127826, PI 134418 and PI 134417 show high levels of antixenosis resistance to B. tabaci MED, and their physico-morphological characteristics are determinant for the expression of resistance. In addition, EO-PG causes toxic and sublethal effects (feeding) to the whitefly, indicating its potential for the alternative management of B. tabaci MED in tomato.
Tomato, Solanum lycopersicum L. (Solanaceae), has great economic importance for Brazil, both for fresh consumption and for industrial processing. However, its productivity is constantly affected by several insect pest species. In this sense, the advance of Bemisia tabaci (Gennadius) MED (Hemiptera: Aleyrodidae) in the main areas of tomato cultivation in Brazil is worrying, due to the high capacity of infestation of the insect, as well as an important vector for numerous lethal viruses to plants. In addition, B. tabaci MED has a history of lower susceptibility to insecticides compared to B. tabaci MEAM1, requiring greater attention from producers. Thus, this work aimed to characterize the possible antixenosis resistance of tomato genotypes of different origins against B. tabaci MED, in addition to evaluating the lethal and sublethal effects of essential oils, as well as their effects on the insects feeding behavior through of the Electrical Penetration Graph (EPG) technique. For resistance tests, preference tests were performed (infestation and oviposition) with and without choice with adults, in addition to the evaluation of colonization by nymphs. At the same time, physical (staining) and morphological (trichomes) analyzes were carried out on the leaves of some selected genotypes, in order to correlate with the observed resistance. The genotypes LA 716, IAC 294, PI 127826, PI 134418 and PI 134417 expressed high levels of antixenosis, while Tainara, PI 126925 and LA 116 showed moderate resistance to B. tabaci MED. The density of glandular trichomes was negatively correlated with the number of adults, eggs/cm² and nymphs/cm² of B. tabaci MED. In turn, the density of non-glandular trichomes and the greater inclination of the trichomes stimulated the colonization of the pest. Substrate color was not correlated with genotype resistance. The essential oils of Pelargonium graveolens (EO-PG, LC50=3.532 µl/mL), Eugenia uniflora (EO-EU, LC50=5.60 µl/mL), Piper callosum (EO-PC, LC50=8.36) and Vitex agnus-castus (EO-VAC, LC50=9.00 µl/mL), as well as the major compound citronellol from OE-PG were toxic to B. tabaci MED. Being the lowest estimated LC50 for EO-PG among the oils and major compounds citronellol (LC50=4.21 µl/mL). Thus, based on the toxicity ratio, EO-PG was more toxic than EO-PC and EO-VAC to whitefly nymphs. In addition, EO-PG showed an ovicidal and adulticidal effect, under laboratory conditions, and a nymphicidal effect, under semi-field conditions, with efficiency similar to commercial insecticides. In the EPG assays, the insecticide cyantraniliprole and the LC25 of EO-PG affected the whitefly stylist activities, reducing the number of walks, (C wave). In addition, all treatments reduced the number and duration of phloem sap ingestion (E2 wave) compared to the control treatment. The LC25 of EO-PG also affected the increased duration per insect and the total duration in the xylem phase. In summary, the results of this study indicate that the genotypes LA 716, IAC 294, PI 127826, PI 134418 and PI 134417 show high levels of antixenosis resistance to B. tabaci MED, and their physico-morphological characteristics are determinant for the expression of resistance. In addition, EO-PG causes toxic and sublethal effects (feeding) to the whitefly, indicating its potential for the alternative management of B. tabaci MED in tomato.
Descrição
Palavras-chave
mosca-branca biótipo Q, Solanum spp., resistência de plantas, derivados botânicos, gráfico de penetração elétrica, whitefly biotype Q, plant resistance, botanical derivatives, electrical penetration graph