Resumo

MARIOTTINI, Yanina; DE WYSIECKI, María L.  e  LANGE, Carlos E.. Temporal variation in grasshopper (Orthoptera: Acridoidea) richness, composition, and density in grasslands of the southern Buenos Aires province. Rev. Soc. Entomol. Argent. [online]. 2012, vol.71, n.3-4, pp.275-288. ISSN 0373-5680.

Grasshoppers are among the dominant invertebrate herbivores in most grassland habitats. The economic importance of grasshoppers has been recognized in Argentina since the XIX century, but many aspects of the biology and ecology of most species remain unknown. The main objective of this study was to determine how grasshopper species richness, composition, and density varied among characteristic plant communities during five successive seasons (2005-06 to 2009-10) in grasslands of the southern Buenos Aires province, an area historically affected by these insects. Twenty two species were collected. Grasshopper species richness was similar between different plant communities and showed a significant decrease in the final year of sampling. The overall density increased significantly in all plant communities during the study, reaching outbreak levels in the last two seasons. Density was over eight times higher in 2009-10 than in 2005-06. The greatest contribution to the increase in density observed was by Dichroplus maculipennis (Blanchard) and Borellia bruneri (Rhen). Dichroplus maculipennis re-emerged as the most serious grasshopper pest in the Pampas, developing an outbreak of historical magnitude that included high densities of up to75 ind/m².

Palavras-chave : Borellia bruneri; Dichroplus maculipennis; Grasshoppers; Outbreaks; Grasslands.

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