5 research outputs found

    Screening test of Diatomaceous Earth as an alternative control method for Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae) eggs

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    The sugarcane borer Diatraea saccharalis is a pest that causes damage to sugarcane fields. The female lays imbricated egg masses on the leave. They cause the greatest damage as larvae, and thus, control before egg hatching is desired to prevent the development of this pest and avoid damage to the plant. Diatomaceous Earth, or diatomite, is inert dust with insecticidal properties. In this work, we aimed to test the activity of Diatomaceous Earth on viable eggs of D. saccharalis as a potential alternative control method for sugarcane borer. D. saccharalis eggs 1 day after oviposition were immersed in a Diatomaceous Earth solution (10% - w/v) for 5, 10, or 15 min and observed every 24 h for 216 h of analysis. During the first 72 h, there were no changes observed in egg morphology, which maintained an oval shape, pale yellow in color. After 96 h, chorion striations were observed in the treatments with 10 and 15 min of exposure and were not present in the chorion controls eggs. Differences between embryo's number it was observed after 96h in the 15 min treatment when compared with the untreated eggs control. Besides that, control larvae completely hatched in 192 h and the treatment with 10 min and 15 min not shown completely hatching suggesting a delay in the embryonic development of the D. saccharalis larvae. Overall, our study is the first report of the application of D. saccharalis eggs, and we believe that Diatomaceous Earth could be a potential tool for the control of Diatraea eggs, however, thorough investigations are required to elucidate the action of this powder on Diatraea and would be an alternative method to interrupt the biological cycle of the pest

    Screening test of Diatomaceous Earth as an alternative control method for Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae) eggs

    Get PDF
    The sugarcane borer Diatraea saccharalis is a pest that causes damage to sugarcane fields. The female lays imbricated egg masses on the leave. They cause the greatest damage as larvae, and thus, control before egg hatching is desired to prevent the development of this pest and avoid damage to the plant. Diatomaceous Earth, or diatomite, is inert dust with insecticidal properties. In this work, we aimed to test the activity of Diatomaceous Earth on viable eggs of D. saccharalis as a potential alternative control method for sugarcane borer. D. saccharalis eggs 1 day after oviposition were immersed in a Diatomaceous Earth solution (10% - w/v) for 5, 10, or 15 min and observed every 24 h for 216 h of analysis. During the first 72 h, there were no changes observed in egg morphology, which maintained an oval shape, pale yellow in color. After 96 h, chorion striations were observed in the treatments with 10 and 15 min of exposure and were not present in the chorion controls eggs. Differences between embryo’s number it was observed after 96h in the 15 min treatment when compared with the untreated eggs control. Besides that, control larvae completely hatched in 192 h and the treatment with 10 min and 15 min not shown completely hatching suggesting a delay in the embryonic development of the D. saccharalis larvae. Overall, our study is the first report of the application of D. saccharalis eggs, and we believe that Diatomaceous Earth could be a potential tool for the control of Diatraea eggs, however, thorough investigations are required to elucidate the action of this powder on Diatraea and would be an alternative method to interrupt the biological cycle of the pest

    Ocean Time-series Reveals Recurring Seasonal Patterns of Virioplankton Dynamics in the Northwestern Sargasso Sea

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    There are an estimated 1030 virioplankton in the world oceans, the majority of which are phages (viruses that infect bacteria). Marine phages encompass enormous genetic diversity, affect biogeochemical cycling of elements, and partially control aspects of prokaryotic production and diversity. Despite their importance, there is a paucity of data describing virioplankton distributions over time and depth in oceanic systems. A decade of high-resolution time-series data collected from the upper 300 m in the northwestern Sargasso Sea revealed recurring temporal and vertical patterns of virioplankton abundance in unprecedented detail. An annual virioplankton maximum developed between 60 and 100 m during periods of summer stratification and eroded during winter convective mixing. The timing and vertical positioning of this seasonal pattern was related to variability in water column stability and the dynamics of specific picophytoplankton and heterotrophic bacterioplankton lineages. Between 60 and 100 m, virioplankton abundance was negatively correlated to the dominant heterotrophic bacterioplankton lineage SAR11, as well as the less abundant picophytoplankton, Synechococcus. In contrast, virioplankton abundance was positively correlated to the dominant picophytoplankton lineage Prochlorococcus, and the less abundant alpha-proteobacteria, Rhodobacteraceae. Seasonally, virioplankton abundances were highly synchronous with Prochlorococcus distributions and the virioplankton to Prochlorococcus ratio remained remarkably constant during periods of water column stratification. The data suggest that a significant fraction of viruses in the mid-euphotic zone of the subtropical gyres may be cyanophages and patterns in their abundance are largely determined by Prochlorococcus dynamics in response to water column stability. This high-resolution, decadal survey of virioplankton abundance provides insight into the possible controls of virioplankton dynamics in the open ocean
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