Publication Date: 2008.
The semi-aquatic grasshopper Cornops aquaticum is native to South America and inhabits lowlands from southern Mexico to Central Argentina and Uruguay. It is host-specific to aquatic plants in the genera Eichhornia and Pontederia. A quarantine population has existed in South Africa for 10 y, and it is planned to release it there as a biological control agent of water hyacinth, E. crassipes. Various studies of C. aquaticum are coordinated under HICWA (www.mpil-ploen.mpg.de). This paper compares the morphometry of the release population and 11 native populations in South America. We tested four hypotheses: 1) South African and South American populations of C. aquaticum differ in morphology; 2) the South African laboratory population is more similar to other isolated populations in South America than to nonisolated populations; 3) morphology differs across sites; 4) morphology differs with host plant. South African populations differed from continental nonisolated populations, but not from continental isolated ones. Isolated populations presented smaller individuals than nonisolated, but there was also a change in male morphology: while in nonisolated populations male wing length was similar to their body length, in isolated populations, male wings were smaller than body length. Females were larger when on Eicchornia azurea than on E. crassipes, while males presented larger wings than their body on E. azurea, and similar lengths on E. crassipes. These morphological changes may have resulted from phenotypic plasticity, selection for small size, or because of a loss of genetic diversity in quantitative traits.
Author affiliation: Adis, Joachim. Institute for Limnology; Alemania
Author affiliation: Sperber, Carlos F. Universidade Federal de Viçosa; Brasil
Author affiliation: Brede, Edward G. Institute for Limnology; Alemania
Author affiliation: Capello, Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentina
Author affiliation: Franceschini, Maria Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentina
Author affiliation: Hill, Martin. Rhodes University; Sudáfrica
Author affiliation: Lhano, Marcos G. Universidade Federal de Viçosa; Brasil
Author affiliation: Marques, Marinê. A;z M.. Universidade Federal de Mato Grosso; Brasil
Author affiliation: Nunes, Ana L.. Muséu Paraense Emílio Goeldi; Brasil
Author affiliation: Polar, Perry. CAB International; Trinidad y Tobago
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas