176 resultados para Lagarta


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Pós-graduação em Agronomia (Proteção de Plantas) - FCA

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The fall armyworm Spodoptera frugiperda is one of the most important pests of maize. Various studies are conducted for their management, integrating chemical and biological control tactics as well as resistant plants. In order to offer alternatives for an efficient management of this pest with minimal use of pesticides, the technology of genetically modified plants resistant to insects has been widely studied. The aim of the present study was to evaluate the natural infestation of larvae of S. frugiperda and their injuries under field conditions in transgenic maize hybrids compared to their conventional isogenic counterparts at two sowing dates and two regions. The hybrids were planted in the off season of 2010 in Jaboticabal, SP, Brazil, and the summer of 2010/2011 in Jaboticabal, and Pindorama, SP, in a randomized block with seven treatments (hybrids) and four replications. Different levels of infestation of larvae occurred throughout the phenological development of plants in conventional and genetically modified hybrids with significant differences between the two groups in most evaluations. The hybrid 2B710HX was the least infested with caterpillars and had the least damaged leaf area. It follows that the Cry1F toxin was the most effective in protecting the plant in relation to other toxic proteins expressed by the other Bt hybrids against infestation and damage promoted by this pest, regardless of time of sowing.

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Pós-graduação em Agronomia (Entomologia Agrícola) - FCAV

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The periodic substitution of cotton cultivars for the farms can modify the levels of economic damages and control of pests, compromising the success in pest control. The objective of this work was to evaluate the effect of simulated defoliation levels in cotton cultivars actually used. The assay was carried out in experimental area of the Polo Apta Centro Norte, in Pindorama, Sao Paulo state. There were evaluated four defoliations levels (0%, 36.8%, 62.1% e 100%), done at a unique operation, in tree times (30, 60 and 90 days after plant emergence) and four cotton cultivars (IAC-25, DeltaOpal, Fibermax 966 and Fibermax 993). The defoliation was done with a scissor simulating the caterpillar damage. Evaluations included the number of open bolls, weight of one boll and 100 seeds, fiber percentage and productivity (kg ha(-1)). The defoliation negatively affected all components of agronomic traits, with the exception of percentage of fiber. The most damaging levels were 62.1 and 100% removal of the leaf blade. The period of higher susceptibility to defoliation occurs from 30 to 60 days after plant emergence.

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

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Pós-graduação em Agronomia (Entomologia Agrícola) - FCAV

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The aim of this work was to evaluate the types of resistance of soybean genotypes to the attack of Spodoptera cosmioides (Walker, 1858), under laboratory conditions. Plants of the soybean genotypes, IAC 100, Dowling, PI 227687, PI 274454, BR 16, IGRA RA 626 RR, PI 227682, BRSGO 8360, IGRA RA 516 RR e P 98Y11 RR, were cultivated in vases and placed in a greenhouse in order to have their leaves used afterwards in free-choice and no-choice no-preference for feeding tests and evaluation of the biological parameters of S. cosmioides fed on the genotypes. For free-choice no preference for feeding test, 10 leaf discs were prepared and placed in Petri dishes equidistantly among themselves, and then two recently-hatched caterpillar per genotype were release in the center of the plate. The same test was performed for third instar larvae, so that one caterpillar per genotype was used. In non-choice test, only one genotype was used in each Petri dish, where two recently-hatched or one third instar caterpillars were released, respectively. For both tests, the attractiveness was assessed at 1, 3, 5, 10, 15, 30, 60, 120, 360, 720 and 1440 minutes after the release of the insects. In addition, the leaf area consumed was evaluated. Randomized blocks design and completely randomized design were used for free-choice and non-choice tests, respectively, with 10 replications. In biology test, recently-hatched larvae were transferred to Petri dishes with leaves of the genotypes, evaluating the period of larvae, pupae and overall (larvae + pupae), viability of larvae, pupae and overall, weight of 12 days-old larvae and 24 hours-old pupae and longevity of the adults. Completely randomized design was used for this test, with 30 replications. Genotypes IGRA RA 516 RR and IGRA RA 626 RR were the least and the most consumed by recently-hatched larvae of S. cosmioides, respectively, in non-choice non-preference for feeding test. Genotypes PI 274454 and PI 227687 were...

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Pós-graduação em Agronomia (Entomologia Agrícola) - FCAV

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Pós-graduação em Agronomia (Entomologia Agrícola) - FCAV

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Pós-graduação em Agronomia (Genética e Melhoramento de Plantas) - FCAV