The Oxycaryum cubense floating mat as refuge of Cornops aquaticum (Orthoptera: Acrididae) in a lake at the Northeast of Argentina.

FRANCESCHINI M.C., J.J. NEIFF & C. AMEDEGNATO

Buenos Aires

Congreso; IV Reunión Binacional de Ecología, Interacción, Espacio y Tiempo; 2010

Asociación Argentina de Ecología, Sociedad de Ecología de Chile y UBA

Cornops aquaticum is a native Latin-American grasshopper which frequently lives on Eichhornia. The aims of this research are 1) to report the presence of this grasshopper on Oxycaryum cubense (Cyperaceae) in relation to climatic conditions and microhabitat structure, and (2) to study and compare survivorship and occurrence of feeding and oviposition of C. aquaticum in the host plant (Eichhornia azurea) and O. cubense. Grasshopper abundance was recorded during all seasons in both plants; field observations and laboratory no-choice tests were conducted to analyse the survivorship, feeding and oviposition of C. aquaticum on both plants. The PCA analyses shown that greater abundance of C. aquaticum on the O. cubense floating mat was related to high values of cloudiness as well as wind speed and low values of temperatures, insolation and photoperiod. We found significant differences between both plant microhabitats comparing leaf biomass (p< 0.0001), leaf density (p< 0.0001) and the height of plants above the water surface (p< 0.0001) with the Kruskal Wallis Test. Feeding test and field observation shown that C. aquaticum is not able to feed and oviposit on O. cubense, but rather uses this macrophyte as refuge under specific climatic conditions.