Induced Senescence Promotes the Feeding Activities and Nymph Development of Myzus persicae (Hemiptera: Aphididae) on Potato Plants

The effect of dark-induced senescence on Solanum tuberosum L. (Solanales: Solanaceae) plants was assessed on the feeding behavior and performance of the green peach aphid, Myzus persicae Sulzer (Hemiptera: Aphididae). Senescence was induced by covering the basal part of the plant with a black cloth for 5 d, avoiding the light passage, but keeping the apical buds uncovered. The basal part of control plants was covered with a white nonwoven cloth. The degree of senescence was determined by measuring the chlorophyll content of the covered leaves. The performance and feeding behavior of M. persicae were studied on the uncovered nonsenescent apical leaves. The aphid’s performance was evaluated by measuring nymphal mortality and prereproductive time. Aphid feeding behavior was monitored by the electrical penetration graph technique. In plants with dark-induced senescence, the aphids showed a reduction in their prereproductive time. Aphids also spent more time ingesting sap from the phloem than in control plants and performed more test probes after the first sustained ingestion of phloem sap. These data suggest that M. persicae ’s phloem activities and nymph development benefit from the nutritional enrichment of phloem sap, derived from dark-induced senescence on potato plants. The induced senescence improved plant acceptance by M. persicae through an increase in sap ingestion that likely resulted in a reduction in developmental time.Fil: Machado Assefh, Cristina Renata. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lucatti, Alejandro Francisco. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alvarez, Adriana Elisabet. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Resistance of tomato genotypes to the greenhouse Whitefly Trialeurodes vaporariorum (West.) (Hemiptera: Aleyrodidae)

The greenhouse whitefly, Trialeurodes vaporariorum Westwood, is the most common and abundant whitefly in Argentine horticultural greenhouse crops, especially in tomato (Solanum lycopersicum). Resistance in some wild tomato relatives, such as S. peruvianum, S. habrochaites and S. pennellii to the greenhouse whitefly has been described. The Mi gene confers effective resistance against several species of insects, among them the sweet potato whitefly, Bemisia tabaci Gennadius. Resistance to T. vaporariorum was found in the prebreeding line FCN 93-6-2, derived from a cross between S. lycopersicum cultivar Uco Plata INTA (MiMi) and the wild line FCN 3-5 S. habrochaites. The purpose of this study was to evaluate resistance to T. vaporariorum in tomato genotypes and to study the relationship between this resistance and the presence of the REX-1 marker, which is linked to the Mi gene. In a free-choice assay, the average number of adults per leaf and the number of immatures on the middle and basal plant parts were analyzed. In a no-choice assay, the oviposition rate and adult survival rate were calculated. For all variables analyzed, FCN 3-5 was the most resistant strain. Variations were found in the F2 progeny between the prebreeding line FCN 13-1-6-1 and cv. Uco Plata INTA. Results from the F2 progeny indicate that resistance to T. vaporariorum may be polygenic with transgressive segregation. Whitefly resistance was found to be independent of the REX-1 marker.Fil: Lucatti, Alejandro Francisco. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alvarez, Adriana Elisabet. Universidad Nacional de Salta. Facultad de Cs.naturales. Escuela de Biologia. Catedra de Quimica Biologica; ArgentinaFil: Machado Assefh, Cristina Renata. Universidad Nacional de Salta. Facultad de Cs.naturales. Escuela de Biologia. Catedra de Quimica Biologica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gilardón, Elsa. Universidad Nacional de Salta; Argentin

Flavonoids from Pterocaulon alopecuroides with antibacterial activity

Three flavonoids, (2R,3R)-5,4′-dihydroxy-3′-O-methyl-7-(γ,γ-dimethylallyloxy)dihydroflavonol 1, (2R,3R)-5,7,4′-trihydroxy-3′-O-methyl-6-(α,α-dimethylallyl)dihydroflavonol 2, and (2R,3R)-5,7,4′-trihydroxy-6-(α,α-dimethylallyl)dihydroflavonol 3, together with three known flavonoids (4 – 6), were isolated from the aerial parts of Pterocaulon alopecuroides. The structures of the compounds were determined by mass and by 1 D and 2 D NMR spectroscopy. Screening of the antibacterial activity of all six compounds was conducted by a disc diffusion test against Bacillus cereus, Bacillus subtilis, Salmonella typhimurium and Proteus mirabilis. The minimum inhibitory concentration (MIC) of the active compounds (2, 3, 4, 6) was determined by a microdilution assay. These compounds were active only against both Gram (+) bacteria with MIC values ≤ 200 μg/mL.Fil: Alarcón, Silvia Rosana. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Carrizo Flores, Roberto Ascencio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; ArgentinaFil: Ocampos, Soledad. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Lucatti, Alejandro Francisco. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Flores Galleguillo, Laura. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Tonn, Carlos Eugenio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; ArgentinaFil: Sosa, Virginia Estela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentin