Tolerance of Hymenaea stigonocarpa mart. Ex Hayne. To glyphosate.

Hymenaea stigonocarpa Mart. ex Hayne has leaves with adaxial and abaxial epidermis covered by a very thick cuticle, in addition to anatomical structures involved in reducing the amount of herbicide absorbed by plants. Thus, we tested the hypothesis that H. stigonocarpa is potentially resistant to the herbicide glyphosate, exposing the plants to different doses (0, 96, 240, 480, and 960 g a.e ha-1). We carried out assessments of the symptoms, anatomy, growth and physiology of the plants and found that exposure to glyphosate negatively affected the height and number of leaves of the plants. Leaf fall resulted in a reduction in the photosynthetic capacity of plants, which responded by investing in stem diameter. Despite this, no visual symptoms of glyphosate toxicity were observed at the concentrations evaluated and histochemical tests did not detect signs of oxidative stress in the leaves, nor starch accumulation, indicating that carbohydrate translocation was not impaired. These results confirm our hypothesis of tolerance of H. stigonocarpa to glyphosate. Furthermore, plants exposed to the lowest doses of glyphosate (96 and 240 g ha-1) showed good growth, photosynthesis, transpiration and photochemical potential responses, indicating a hormetic effect in this application range.

Biomarkers of pollution by glyphosate in the lichens, Parmotrema tinctorium and Usnea barbata.

Glyphosate is a herbicide commonly used in agriculture for weed control. Current agricultural production demands vast amounts of this product, which are applied by ground or aerial spraying. The concomitant aerial currents promote glyphosate drift to vegetated or urban areas. In this context, we hypothesized that the lichens, Parmotrema tinctorum and Usnea barbata, could be sensitive to the action of glyphosate and therefore be used to bio-indicate the presence of this herbicide in areas affected by drift. Since living organisms respond in different ways to the action of herbicides, our interest was also to indicate biological markers responsive to the action of glyphosate, through concentrations and exposure times of the thallus, besides identifying the most sensitive species. We evaluated the effect of different concentrations (0.0, 4.8, 9.6, and 19.2 mg L-1) and exposure times (24, 48, and 72 hours) to glyphosate on the morphoanatomy, photobiont vitality, photosynthetic efficiency, and oxidative metabolism of the thalli. We found that the lichens, P. tinctorum and U. barbata, respond to glyphosate stress, with prospects for use in the biomonitoring of pollutant dispersal from plantation areas. When using P. tinctorum as a bioindicator, lichen morphoanatomy, photobiont vitality, and photosynthetic pigment concentration were efficient biomarkers for the effect of concentration and exposure time. For U. barbata, the lichenic morphoanatomy and the activity of SOD and APX enzymes were essential tools to indicate the herbicide action. Parmotrema tinctotum, however, was characterized as more sensitive in bio-indicating the presence of this herbicide to diagnose the air quality in urban areas or vegetation sectors adjacent to agricultural environments.

Parasitoides de Ornidia obesa Fabricius (Diptera: Syrphidae) coletados em fezes de galinha no Brasil / Parasitoids of Ornidia obesa Fabricius (Diptera: Syrphidae) collected in chicken feces in Brazil

This study reports the occurrence of Pachycrepoideus vindemmiae (Rondani) (Hymenoptera: Pteromalidae) and Spalangia cameroni Perkins (Hymenoptera: Pteromalidae) as parasitoids of Ornidia obesa Fabricius (Diptera: Syrphidae) in poultry farms in Morrinhos, Goiás, state Brazil. Samples of chicken feces were collected at two weeks intervals and taken to the laboratory. The pupae were extracted by water flotation. Each pupa was placed in capsules of gelatin until the emergence of dipterous or their parasitoids. The parasitism percentage of P. vindemmiae and S. cameroni was 5.1 percent.