ABSTRACT
Insects show morphometric variations associated with the environment that may be the result of phenotypic response or genetic inheritance, or both. Thereby, studies that emphasise the variability in body size are very useful for understanding the dynamics and the stability of ecological systems. Cornops aquaticum (Bruner, 1906) (Acrididae) is a semi-aquatic grasshopper, distributed from the southeast of Mexico to the south of Buenos Aires Province, Argentina, and is intimately associated with the aquatic macrophytes Eichhornia spp. and Pontederia spp. In its wide habitat distribution, C. aquaticum shows variations in its life cycle and morphometric differences that were observed suggesting geographic and host plant influence. Considering these findings, this study aimed to find out the morphometric characteristics of this species at the Pantanal of Poconé - MT, using the protocol of the project "HICWA - Host-Insect Coevolution on Waterhyacinth", as well as to assess possible differences in each stage of development between the sexes and among seasonal periods (flood, high water, low water and dry). During 12 months a total of 600 individuals were collected in monthly collections of 50 grasshoppers, and of this total, 261 were adults and 339 nymphs. The following measurements were taken: total length (A); body length (B); wing length (I) and measurement of the hind femur (H). The results showed that both male and female have different measurements but not correlated with seasonal periods. The average obtained for each character and the seasonality showed the highest values during the flood period. In nymphs, the measurement of the posterior femur presented the lower variation between individuals and characters.
