Seawater Mg:Ca and Sr:Ca ratios are biogeochemical parameters reflecting the Earth–ocean–atmosphere dynamic exchange of elements. The ratios’ dependence on the environment and organisms' biology facilitates their application in marine sciences. Here, we present a measured single-laboratory dataset, combined with previous data, to test the assumption of limited seawater Mg:Ca and Sr:Ca variability across marine environments globally. High variability was found in open-ocean upwelling and polar regions, shelves/neritic and river-influenced areas, where seawater Mg:Ca and Sr:Ca ratios range from ∼4.40 to 6.40 mmol:mol and ∼6.95 to 9.80 mmol:mol, respectively. Open-ocean seawater Mg:Ca is semiconservative (∼4.90 to 5.30 mol:mol), while Sr:Ca is more variable and nonconservative (∼7.70 to 8.80 mmol:mol); both ratios are nonconservative in coastal seas. Further, the Ca, Mg, and Sr elemental fluxes are connected to large total alkalinity deviations from International Association for the Physical Sciences of the Oceans (IAPSO) standard values. Because there is significant modern seawater Mg:Ca and Sr:Ca ratios variability across marine environments we cannot absolutely assume that fossil archives using taxa-specific proxies reflect true global seawater chemistry but rather taxa- and process-specific ecosystem variations, reflecting regional conditions. This variability could reconcile secular seawater Mg:Ca and Sr:Ca ratio reconstructions using different taxa and techniques by assuming an error of 1 to 1.50 mol:mol, and 1 to 1.90 mmol:mol, respectively. The modern ratios’ variability is similar to the reconstructed rise over 20 Ma (Neogene Period), nurturing the question of seminonconservative behavior of Ca, Mg, and Sr over modern Earth geological history with an overlooked environmental effect.
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A piroplasmose equina causada por Theileria equi acomete os equinos de forma endêmica no Brasil e em diversos outros países tropicais e subtropicais. Considerada uma das mais
Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae) is considered to be one of the major pest insects in fruit orchards worldwide. Bacillus thuringiensis Berliner (Bacillales: Bacillaceae) strains are widely used as biological control agents and show high biological activity against different insect species. The objective of this study was to evaluate the biological activity of different strains of B. thuringiensis against A. fraterculus larvae and adults. Bioassays were performed using suspensions of bacterial spores/crystals of B. thuringiensis var. israelensis (Bti), kurstaki (Btk), and oswaldocruzi (Bto) strains at three concentrations [2 × 107, 2 × 108, and 2 × 109 colony-forming units per ml (CFU ml-1)]. At a concentration of 2 × 109 CFU ml-1, a significant larval effect (mortality 60%) was observed when compared with the control treatment. Larvae that ingested spore/crystal suspensions of Bti, Btk, or Bto bacterial strains exhibited significant larval and pupal deformations, leading to a significant decrease (~50%) in the completion of the insects' biological cycle (egg to adult). The B. thuringiensis strains (Bti, Btk, or Bto) at a concentration of 2 × 109 CFU ml-1 in combination with one food attractant (BioAnastrepha 3% or CeraTrap 1.5%) in formulations of toxic baits provided high mortality (mortality > 85%) of A. fraterculus adults 7 d after treatment. However, the Btk strain in combination with CeraTrap 1.5% caused mortality of 40%. On the basis of these results, the native bacterial strains Bti, Btk, and Bto were considered to be promising candidates as biological control agents against A. fraterculus.
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