Amostragem e distribuição espacial de colônias de formigas cortadeiras (Hymenoptera: Formicidae) em eucaliptais / Sampling and spatial distribution of colonies of leaf cutting ants (Hymenoptera: Formicidae) in eucalyptus plantations

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

This work was developed in the municipalities of Abaeté, Bom Despacho, Ibitira and Martinho Campos, Minas Gerais State in 18 stands of Eucalyptus spp. with areas from 19.8 to 52.0 hectares each one and totaling 706.8 hectares. The objective was to study the spatial distribution and to test a sampling plan with transects in strips in eucalyptus stands to evaluate the distribution of colonies of leaf cutting ants from the borders to inside the eucalyptus stands and to compare this sampling method with random parcels. These stands were divided in sample units of six meters wide by twenty meters length where the colonies of leaf-cutting ants were identified, counted and measured its largest length and width of loose soil. The number and the area of loose soil for each colony of leaf-cutting ants its distance from the nearest border of the eucalyptus stands were obtained with these sample units. The spatial distribution of these colonies was combined for the four municipalities. The general average of the number and area of loose soil of the colonies of leaf-cutting ants was 16.4 and 35.5 m/ha and their area was 15.5; 17.9; 16.5 and 15.8 colonies of leaf-cutting and 70.5; 32.6; 27.1 and 16.2 m of area of loose soil/ha for Abaeté, Bom Despacho, Ibitira and Martinho Campos, respectively. The greatest distance between transects in strips was 192, 120, 120 and 168 m for Abaeté, Bom Despacho, Ibitira and Martinho Campos, respectively. The distribution of the colonies of this pest showed that 50.0% of them were found up to 110 m from the borders of these stands. The test of identity model showed that the equations adjusted for the accumulated percentage of the number and the area of loose soil for the colonies of leaf-cutting ants in relation to the borders of the eucalyptus stands were similar in the four areas. The area of 165.33, 294.64, 408.37, 521.63 and 625.44 would be necessary to be controlled to reach 20, 40, 60, 80 and 100% of the leaf-cutting ants colonies in the eucalyptus stands. The sampling method with transects in strips presented the best correlation coefficients with the census of colonies of leaf-cutting ants in the respective areas. For this reason this methodology can be used in areas with higher or lower infestation of colonies of leaf-cutting ants. Besides, the eucalyptus stands presented similar pattern for the distribution of colonies of leaf-cutting ants in relation to the borders and transects in strips represent the most suitable method to sample colonies of these insects in the borders and inside the eucalyptus stands.

ASSUNTO(S)

distribuição espacial leaf cutting ants formigas cortadeiras talhões de eucalipto eucalyptus stands spatial distribution entomologia agricola

ACESSO AO ARTIGO

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