Zoological Studies

Vol. 51 No. 1, 2012

Feeding Habits and Trophic Niche Overlap of Aquatic Orthoptera Associated with Macrophytes

Soledad Capello1,*, Mercedes Marchese1,2, and María L. de Wysiecki3

1Instituto Nacional de Limnología (INALI-CONICET-UNL), Ciudad Univ., Santa Fe 3000, Argentina
2Facultad de Humanidades y Ciencias-UNL. Ciudad Univ., Paraje El Pozo, Santa Fe 3000, Argentina
3Centro de Estudios Parasitológicos y de Vectores (CEPAVE) (CCT-La Plata- CONICET- UNLP), Calle 2 nº 584, La Plata 1900, Argentina

Soledad Capello, Mercedes Marchese, and María L. de Wysiecki (2012) A dietary analysis is a frequent 1st step in studying an animal’s ecology, because its diet directly reflects resource use and can provide insights into habitat utilization and competitive interactions. Little is known concerning orthopteran species that inhabit moist or wet environments, because such species do not usually become pests. We hypothesized that aquatic orthopterans feed on only a few macrophytes, and they show trophic niche overlap. Feeding habits of 7 orthopteran species associated with macrophytes, the botanical composition of the diets of these insects, and their trophic niche breadth and overlap were analyzed from the Middle Paraná River, Argentina. The diet composition by a microanalysis of feces under an optical microscope and the frequency of occurrence of each plant, food niche breadth, niche overlap, and food specialization level of every species were determined. Only Paulinia acuminata, Marellia remipes, and Cornops aquaticum exclusively consumed aquatic plants. The water hy cinth (Eichhornia crassipes) was the unique macrophyte consumed by all orthopteran species studied, although in different proportions. The greatest trophic niche breadth was shown by Coryacris angustipennis, and the highest Berger-Parker index value was found for C. aquaticum, which also showed high specificity. The species C. aquaticum, C. angustipennis, Conocephalus sp., and Scudderia sp. showed niche overlap; however, they can live in the same habitats because resources are very abundant. This is the 1st analysis of the diet compositions of these species (except C. aquaticum), and it is important information to explain orthopteran assemblages associated with macrophytes in this Argentine river.

Key words: Diet, Herbivores, Orthoptera, Water hyacinth, Paraná River.

*Correspondence: E-mail:solecapello@gigared.com