The effect of soil texture, landscape, grass species, age and system of pasture formation on attack intensity of Atarsocoris brachiariae Becker was studied. No differences were found among grass species or landscape on attack intensity of this bug. Higher densities of A. brachiariae were observed in sandy soils, in pastures over four years old, in those with traditional formation and between 20-30 cm underground. Attack of A. brachiariae occurred in patches specially in the transition areas between dead grass and normal grow- ing grass.

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Attack of Atarsocoris brachiariae Becker, a new pest of pasturelands in Mato Grosso, Brazil

This experiment was carried out in Arenito Research Center-UEM, in Cidade Gaucha-PR, from October/1997 to March /1998, to evaluate in coastcross-1 ( Cynodon dactylon (L.) Pers) grazing, in four levels of dry matter residue (DMR: 1,978; 2,130; 2,545; 3,857 kg of DM/ha), with a continuous allotment system and variable number of allotments, the densities and participation of botanical component. A completely randomized design with two replications was used. Forage density, participation of botanical components and leaf/stem ratio were evaluated in inferior strata (0-10 cm) and superior ones (10-20 cm) of the pasture, according to the levels of DMR. The pasture density (g of DM/m 3 ) in superior and inferior strata had a positive relation with the DMR levels and negative when associated to the period (days) of the experiment. Dead material (DM) percentage was higher in the inferior stratum than green stem (GC)and green leaves (GL) percentages. In the superior stratum, DM and GL had a greater participation, however the GL increased while DM levels increased as well.

Avaliacao da densidade de uma pastagem de coastcross-1 (Cynodon dactylon (L.) Pers) em niveis residuais de materia seca sob pastejo

This research presents data on the population dynamics for adults of Atarsocoris brachiariae. Comparisons are made against the precipitation volume for the region of Rondonopolis, MT, Brazil. Population surveys were performed at Fazenda Guarita, in a 4-hectare, 8-year old Brachiaria decumbens rangeland highly infested with A. brachiariae, formerly an experimentation field owned by Empresa Mato-grossense de Pesquisa, Assistencia e Extensao Rural S/A (EMPAER/MT/Rondonopolis). Weekly soil samples were taken at random from January 1995 through December 1997; sample size was 10 × 20 × 40 cm (width, length, depth). The highest population density for adults (1412/2318 - 60.91%) was verified at the depth between 20 and 40 cm. Precipitation volumes indicated a positive correlation with number of adults (P < 0.01). The greatest number of adults (72.6%) was collected in the dry season.

https://periodicoscientificos.ufmt.br/ojs/index.php/biodiversidade/article/download/89/80

POPULATION DYNAMICS FOR ADULTS OF Atarsocoris brachiariae (HEMIPTERA: CYDNIDAE), COMPARISONS ARE MADE AGAINST THE PRECIPITATION VOLUME FOR THE REGION OF RONDONÓPOLIS, MT.

J.A Gomide

Papers

Fatores de rebrota das gramineas forrageiras