The present study aimed to optimize ozone (O) treatments, as gas and dissolved in water, to remove difenoconazole and linuron in carrots. We employed a central composite design to study three variables governing the efficacy of treatments: O concentration, temperature and treatment time. The temperature did not influence the efficacy of treatments. The removal percentage of pesticides increases with increases in ozone concentration and the time of treatment. O application promoted the removal of more than 80% of pesticides when the roots were exposed for approximately 120min at 5 and 10mgL, respectively, in treatments with O as gas and dissolved in water. After storage, pesticide removal was higher than 98% for difenoconazole and 95% for linuron. The degradation products from the pesticides resulting from treatment were monitored, but none were found. This is the first report demonstrating the removal of difenoconazole and linuron from carrots by ozone.
Chronic lead exposure induces hypertension in humans and animals, affecting endothelial function. However, studies concerning acute cardiovascular effects are lacking. We investigated the effects of acute administration of a high concentration of lead acetate (100 µΜ) on the pressor response to phenylephrine (PHE) in the tail vascular bed of male Wistar rats. Animals were anesthetized with sodium pentobarbital and heparinized. The tail artery was dissected and cannulated for drug infusion and mean perfusion pressure measurements. Endothelium and vascular smooth muscle relaxation were tested with acetylcholine (5 µg/100 µL) and sodium nitroprusside (0.1 µg/100 µL), respectively, in arteries precontracted with 0.1 µM PHE. Concentrationresponse curves to PHE (0.001-300 µg/100 µL) were constructed before and after perfusion for 1 h with 100 µΜ lead acetate. In the presence of endothelium (E + ), lead acetate increased maximal response (E max ) (control: 364.4 ± 36, Pb 2+ : 480.0 ± 27 mmHg; P < 0.05) and the sensitivity (pD 2 ; control: 1.98 ± 0.07, 2.38 ± 0.14 log mM) to PHE. In the absence of endothelium (E -) lead had no effect but increased baseline perfusion pressure (E + : 79.5 ± 2.4, E -: 118 ± 2.2 mmHg; P < 0.05). To investigate the underlying mechanisms, this protocol was repeated after treatment with 100 µM L-NAME, 10 µM indomethacin and 1 µM tempol in the presence of lead. Lead actions on E max and pD 2 were abolished in the presence of indomethacin, and partially abolished with L-NAME and tempol. Results suggest that acute lead administration affects the endothelium, releasing cyclooxygenasederived vasoconstrictors and involving reactive oxygen species.
ResumoO ácaro-rajado, Tetranychus urticae Koch, 1836 (Acari: Tetranychidae) é uma praga polífaga e causa grandes prejuízo a agricultura brasileira. O controle dessa praga geralmente é realizado por produtos de origem sintética. Com tudo, os óleos essenciais com propriedade acaricida, podem ser considerados uma alternativa no controle desta praga. Assim, os objetivos deste trabalho foram identificar a composição química e avaliar a toxicidade por fumigação do óleo essencial
Chemical composition and toxicity of eucalyptus essential oil on spotted spider mite AbstractThe spotted spider mite, Tetranychus urticae Koch, 1836 (Acari: Tetranychidae) is a polyphagous pest which causes extensive damage to Brazilian agriculture. The control of this pest is usually performed by synthetic origin products. Thus, the essential oils with acaricide property can be resources considered as an alternative to control this pest. The objective of this study was to identify the chemical composition and evaluate the fumigation toxicity of Eucalyptus citriodora (Hook.) KD Hill & LAS Johnson essential oil on T. urticae. The essential oil extraction was performed by hydrodistillation, usinga Clevenger type apparatus . The compounds identification was made comparing the obtained mass spectra with the available spectra in the database of the spectral library Willey 330,000 and by the Kovats index (IK), calculated for each compound. Adult female spotted spider mite were subjected to doses of 3.57, 7.14, 10.71, 14.28 and 17.85 μL L -1 of the essential oil air in fumigation chambers during 24, 48 and 72 hours. Subsequently, lethal concentration (LC 50 ) of the essential oil was estimated. Ten compounds were identified, being the citronellal (68.20%) the major compound. The LC 50 value observed after 24, 48 and 72 hours of exposure to essential oil were 17.55, 17.00 and 10.50 μL L -1 of air, respectively, and the fecundity of T. urticae females reduced with an increase of the used concentrations.
Essential oils from plants have remarkable biological properties, for example as insecticides and acaricides. Here we provide chemical analysis and evaluate the toxicity of the essential oil of Mentha piperita (Lamiaceae) and its main constituent menthol against Tetranychus urticae Kogan 1836 (Acari: Tetranychidae), a polyphagous pest present in agricultural landscapes. The essential oil was obtained from M. piperita leaves via hydrodistillation. Subsequently, concentration-response bioassays in adult females (fumigation and contact) were conducted to evaluate the lethal effect on the mite with three exposure intervals. We also evaluated the reproductive performance of females after exposure. Both substances were lethal in the fumigation bioassay, in addition, the essential oil was about 6-fold more toxic than menthol after 24 and 48 h of exposure. The fecundity of T. urticae females decreased inversely proportional to the increase of the used concentrations. Essential oil contact tests showed sublethal effects, with low mortality and reproductive stimulation of T. urticae females. Therefore, menthol and M. piperita essential oil can be considered potential acaricides for T. urticae by fumigant exposure due to the deleterious effect in adults and reduction in the number of individuals in subsequent generations, that represents a promising management tool.
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