INALI   02622
INSTITUTO NACIONAL DE LIMNOLOGIA
Unidad Ejecutora - UE
artículos
Título:
On morphometric differences in the grasshopper Cornops aquaticum from Eichhornia spp. in South America and South Africa.
Autor/es:
ADIS, J., SPERBER C.F., BREDE E.G., CAPELLO, S., FRANCESCHINI, M.C., HILL, M., LHANO, M.G., MARQUES, M.I., NUNES, A.L. & POLAR, P.
Revista:
JOURNAL OF ORTHOPTERA RESEARCH
Referencias:
Lugar: Estados Unidos; Año: 2008 vol. 17 p. 141 - 147
ISSN:
1082-6467
Resumen:
The semi-aquatic grasshopper Cornops aquaticum is native to South America and inhabits lowlands from southern Mexico to Central Argentina and Uruguay (Adis et al. 2006). It is host specific to Eichhornia spp. and Pontederia spp. (cf. Adis & Junk 2003; Adis & Victoria 2001; Lhano et al. 2005) and is planned to be released in South Africa as a biological control agent of the water hyacinth E. crassipes (cf. Oberholzer & Hill 2001). To better understand the organism prior to release, several studies are being undertaken as part of a project called HICWA (www.mpil-ploen.mpg.de). The focus of this study is to compare the morphometry of both the release population and 11 native populations in South America, and suggest possible reasons the differences seen. The following hypotheses were tested: 1.      There is a difference in morphology between the South African and the continental populations of C. aquaticum grasshoppers. 2.      The South African population is more similar to other isolated populations in comparison to the non-isolated continental populations. 3.      The variance of morphological characters in the South African population is smaller than that of continental populations. 4.      There is a difference between Cornops aquaticum populations using Eichhornia azurea as a host plant in comparison to those populations using Eichhornia crassipes. Results showed that irrespective of sexual differences, C. aquaticum populations had variations in body dimensions in response to geographical situation and host plant. Further, individuals in isolated populations showed smaller overall size. This may be as a result of selective pressures for size reduction, phenotypic plasticity, or due to a loss of genetic diversity in quantitative traits. Finally, results indicate that although female C. aquaticum are able to change their overall body size in relation to geography and host plant, males have a greater level of flexibility altering their morphology disproportionally in response to these factors.