Resumo

ALFARO, Fermín M.; PIZARRO-ARAYA, Jaime; CEPEDA-PIZARRO, Jorge  e  BODINI, Andrés. Composition and distribution of the Orthoptera assemblage (Insecta) in an arid basin in North-Central Chile. Rev. Fac. Cienc. Agrar., Univ. Nac. Cuyo [online]. 2011, vol.43, n.1, pp.97-110. ISSN 1853-8665.

The Elqui river basin (Coquimbo Region, Chile) is an important fruit-growing and tourist center in the North and Central area of Chile, where climate conditions are characterized by a rise in temperature and decrease in precipitation. Within the context of global warming, the hydrographical basin of the Elqui River is expected to show a rising trend toward aridity, as well as alterations in the phenology of plants and arthropods, and changes in the local biodiversity and richness of ecosystems. In this respect, this research analyzes the taxonomic composition, abundance and distribution of the assemblage of Orthoptera (Insecta) through hand-collecting in rangeland and farmland of the localities of Marquesa, Diaguitas, and Pisco Elqui in the Elqui valley. We documented the taxonomic composition and abundance of the Orthoptera assemblage (Insecta), and analyzed the spatial distribution of its component species by using SIG. We also documented the potential orthopterans have to become a plague in this arid watershed of North-Central Chile. A total of 204 specimens were captured, belonging to four families and six species, five of which were common to rangeland and farmland. Acrididae was the most abundant and varied family among the study sites (65.2% of the total captured) and Trimerotropis ochraceipennis the most abundant species. The families Gryllidae, Ommexechidae and Tristiridae were represented by only one species. The presence of these species in the rangeland can be a risk factor for agriculture, considering potential irruptive outbreaks under certain climate conditions, and can also cause damage to crops, plantations and grasslands. The relationship between microdistribution of the Orthoptera assemblage present in the Elqui valley and the NDVI index showed a clear preference for dense and not so dense vegetation (NDVI = 0.1 - 0.49). This is a first approach to the study of orthopterans which are considered potential plagues to the Elqui valley.

Palavras-chave : Orthoptera; Arid watershed; Chilean rangeland; Population outbreaks; Elqui valley.

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