Invertebrate herbivory on floating-leaf macrophytes at the northeast of Argentina: Should the damage be taken into account in estimations of plant biomass?

We assessed the damage produced by invertebrate herbivores per leaf lamina and per m2 of populations floating-leaf macrophytes of Neotropical wetlands in the growth and decay periods, and assessed if the damage produced by the herbivores should be taken into account in the estimations of plant biomass of these macrophytes or not. The biomass removed per lamina and per m2 was higher during the growth period than in decay period in Nymphoides indica and Hydrocleys nymphoides, while Nymphaea prolifera had low values of herbivory in growth period. During decay period this plant is only present as vegetative propagules. According to the values of biomass removed per m2 of N. indica, underestimation up to 17.69% should be produced in cases that herbivory do not should be taking account to evaluate these plant parameters on this macrophyte. Therefore, for the study of biomass and productivity in the study area, we suggest the use of corrected lamina biomass after estimating the biomass removed by herbivores on N. indica. The values of damage in N. indica emphasize the importance of this macrophyte as a food resource for invertebrate herbivores in the trophic networks of the Neotropical wetlands.Fil: Martínez, Fedra Solange. 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; ArgentinaFil: 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; Argentin

Age Structure and Feeding of the Neotropical Grasshopper Cornops aquaticum (Bruner) (Orthoptera: Acrididae) on Water Hyacinth.

We aimed to evaluate the variation in the age structure of Cornops aquaticum (Bruner) population and its relation to the host plant biomass and the feeding of the different age classes of this grasshopper on the Water Hyacinth Eichhornia crassipes along two years, in a Paraná River floodplain lake (Chaco, Argentina). Individuals of C. aquaticum were captured with a 70-cm diameter sweep and separated in nymphs A (instars I and II), nymphs B (instars III to VI), adult females and adult males; host plant biomass was sampled using a ring with a 0.30 m2 diameter. Relative daily feeding of C. aquaticum population was calculated by multiplying the number of individuals captured per minute by the daily consumption by individual obtained in each age classes. We found that the age structure and the relative daily feeding of C. aquaticum varied between seasons and years. The highest values of grasshopper abundance, leaf biomass and relative daily feeding of C. aquaticum population were observed in summer 2006. Plant biomass was directly correlated with nymph abundance and not correlated with adult abundance. Plant biomass available as refuge (leaves), food (laminas) and oviposition site (petioles) to C. aquaticum represented up to 62 % of the total plant biomass. The results obtained in C. aquaticum show the importance of considering total plant biomass and plant biomass available for herbivores separately. Our study highlights the need to find an adequate method to estimate density of C. aquaticum and other semi-aquatic grasshoppers in the Paraná River floodplain involving different seasons, years and water phases (rising and falling).Fil: Franceschini, Maria Celeste. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Nordeste. Centro de Ecologia Aplicada del Litoral (i); Argentina;Fil: de Wysiecki, Maria Laura. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - la Plata. Centro de Est.parasitol.y de Vectores (i); Argentina;Fil: Poi, Alicia Susana G.. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Nordeste. Centro de Ecologia Aplicada del Litoral (i); Argentina

Preferencia alimentaria de Neochetina eichhorniae (Coleoptera: Curculionidae) en plantas acuáticas de diferente valor nutritivo

Neochetina eichhorniae (Coleoptera: Curculionidae) es un herbívoro asociado a los camalotales de Eichhornia crassipes y E. azurea de áreas nativas. Los objetivos de este trabajo fueron: (1) evaluar la preferencia alimentaria de los adultos de N. eichhorniae bajo condiciones naturales, utilizando especies de macrófitas nativas que coexisten con las dos plantas huéspedes y (2) analizar la preferencia alimentaria en relación con el contenido de nitrógeno, fósforo y lignina, como indicadores del valor nutritivo de las hojas. Las especies de plantas estudiadas fueron: E. crassipes, E. azurea, Oxycaryum cubense, Thalia multiflora, Salvinia biloba, Pistia stratiotes, Ludwigia peploides y Nymphaea prolifera. Se realizaron pruebas de preferencia de opción doble y múltiple, utilizando raciones de las macrófitas, en presencia y ausencia de las plantas huéspedes. Se cuantificó, respectivamente, el área total dañada por macrófita y por curculiónido y se correlacionó con el valor nutritivo de las hojas. Las plantas huéspedes, cuya superficie dañada varió entre 115 y 284,76 mm2, fueron las especies preferidas. La superficie dañada tuvo correlación positiva con el contenido de nitrógeno de las hojas de las distintas especies de plantas. El contenido de fósforo, lignina y el cociente L: N no tuvieron relación con la preferencia. Neochetina eichhorniae tuvo especificidad por ambas plantas huéspedes, cuyas hojas tuvieron alto contenido de nitrógeno. Estos resultados constituyen una contribución preliminar debido a que todavía es poco conocido el efecto del valor nutritivo de las macrófitas sobre la preferencia alimentaria de los invertebrados herbívoros en los sistemas acuáticos subtropicales.Neochetina eichhorniae (Coleoptera: Curculionidae) is one herbivore associated to Eichhornia crassipes and E. azurea floating meadows in native areas. The aims of this study were: (1) to evaluate the feeding preference of adults of N. eichhorniae under natural conditions, using native species of macrophytes that coexist with the two host plants, and (2) to assess feeding preference in relation to nitrogen, phosphorous and lignin content as indicators of the nutritive value of the leaves. The plant species included in this study were: E. crassipes, E. azurea, Oxycaryum cubense, Thalia multiflora, Salvinia biloba, Pistia stratiotes, Ludwigia peploides and Nymphaea prolifera. Double and multiple-feeding choice tests were performed under natural conditions, using feeding rations, including and excluding the host plants. Total damaged area per macrophyte and leaf area damaged by weevil were quantified and correlated with the different nutritional values of leaves. The host plants, with damage area varied between 115 and 284.76 mm2 , were the most preferred plants. There was a positive correlation between the damage area and the leaf nitrogen content of the plant species. Feeding preference was unrelated to either phosphorous and lignin content or L: N ratio. Neochetina eichhorniae have high specificity for both host plants, which leaves had high nitrogen content. Because the effect of the nutritive value on the feeding preference of invertebrate herbivores from the subtropical aquatic systems remain still unknown, these results are an preliminary contributionFil: Martínez, Fedra Solange.Fil: Franceschini, Maria Celeste.Fil: Poi, Alicia Susana G.

Disentangling vegetation structure effect on invertebrate communities in contrasting growth periods in subtropical protected wetlands of Argentina

This study assesses the effect of vegetation structure on the subtropical invertebrate communities in contrasting sampling dates of macrophyte populations in the RAMSAR site of Iberá wetlands, South America. Invertebrates associated with the submersed Egeria najas and the floating rooted Pontederia azurea were chosen to provide a model involving different microhabitat complexity. The results suggest that vegetation structure provided by the two macrophyte species supported significant differences in the density of animals, with invertebrate abundance of E. najas twice as high as on P. azurea. Abundance showed no significant differences in both contrasting sampling dates, growth and decline. Our result clearly showed invertebrates exclusively associated with each macrophyte species, as well different invertebrate taxa dominating in each sampling date (decline: Cladocera; growth: Aphididae, Belostomatidae and Planorbidae). We also show that working at the taxonomic levels of family could be a sensible trade-off between taxonomic identification effort versus reaching reliable and useful results for environmental monitoring and natural resource management in highly diverse subtropical wetlands. Our results emphasize the role of vegetation structure on invertebrate communities, as well suggest that the growth cycle of macrophyte populations could be a relevant variable influencing these animals in pristine subtropical wetlands.Fil: Sabater, Lara Milena. 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; ArgentinaFil: 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; ArgentinaFil: Gallardo, Luciana Irene. 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. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura; ArgentinaFil: Coronel, Juan Manuel. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura; ArgentinaFil: Perez, Alejandra Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentin

Morphometric differences in the grasshopper Cornops aquaticum (Bruner, 1906) from South America and South Africa

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.Fil: Adis, Joachim. Institute for Limnology; AlemaniaFil: Sperber, Carlos F. Universidade Federal de Viçosa; BrasilFil: Brede, Edward G. Institute for Limnology; AlemaniaFil: 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; ArgentinaFil: 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; ArgentinaFil: Hill, Martin. Rhodes University; SudáfricaFil: Lhano, Marcos G. Universidade Federal de Viçosa; BrasilFil: Marques, Marinê. A;z M.. Universidade Federal de Mato Grosso; BrasilFil: Nunes, Ana L.. Muséu Paraense Emílio Goeldi; BrasilFil: Polar, Perry. CAB International; Trinidad y Tobag

Invertebrados en arroceras de Corrientes ¿Son importantes para diseñar e implementar un sistema de manejo integrado de plagas?

El conocimiento sobre los invertebrados asociados al cultivo de arroz en el país es limitado, principalmente centrado en humedales naturales. Este estudio destaca la complejidad taxonómica y funcional de los macroinvertebrados en arroceras, subrayando su papel como humedales artificiales y sostén de biodiversidad. Los resultados muestran una biodiversidad comparable a la de sistemas naturales, como humedales periurbanos. Aunque ambas arroceras exhiben comunidades diversas y complejas, se observan diferencias en abundancia y composición taxonómica, posiblemente relacionadas con prácticas de manejo. La exclusividad de ostrácodos en una arrocera indica un manejo óptimo, mientras que la presencia abundante de indicadores de calidad ambiental sugiere prácticas efectivas de control de plagas. Se destaca la importancia de los invertebrados como herramienta de diagnóstico para evaluar distintos manejos. Se recomienda la implementación de monitoreos de macroinvertebrados para desarrollar un sistema de manejo integrado de plagas más sostenible desde el punto de vista ambiental y económico en arroceras de Corrientes.Fil: Sabater, Lara Milena. 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; ArgentinaFil: Bertucci, Sabrina Eliana. 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; ArgentinaFil: Perez, Alejandra Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: 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; Argentin

An unusual case of epigeal cryptocotylar germination in Rollinia salicifolia (Annonaceae)

An unusual case of epigeal cryptocotylar germination found in Rollinia salicifolia Schltdl. (Annonaceae) is described and is discussed in relation to the terminology used for germination studies. The terms cryptocotylar and phanerocotylar are used to describe the permanence of cotyledons within the seed coat or endocarp; the terms epigeal and hypogeal are used to refer the position of cotyledons in relation to ground level. The terms to describe position about ground level and permanence of cotyledons within the seed coat or endocarp are not used simultaneously in many papers, and some authors consider the terms cryptocotylar and hypogeal to be synonyms. Cases of epigeal cryptocotylar germination seem to be scarce in the literature. The morphological characters shown by R. salicifolia seeds and seedlings - a non-chlorophyllous embryo, abundant endosperm, thick woody seed coat, thickened hypocotyl and non-photosynthetic haustorial cotyledons - are closely related to its epigeal cryptocotylar germination. This is the first record of this type of germination in Argentina. © 2004 The Linnean Society of London.Fil: Franceschini, Maria Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentin

Número e duração dos estágios ninfais do gafanhoto neotropical Cornops aquaticum (Acrididae: Leptysminae) NA Argentina

Cornops aquaticum es un acridio semiacuático que vive en estrecha asociación con Pontederiaceas, especialmente del género Eichhornia. En su área de distribución nativa, la información existente respecto al ciclo de vida esta referida a poblaciones de Brasil y Uruguay. En este trabajo se determinó el número de estadios ninfales y la duración del desarrollo ninfal de C. aquaticum en Argentina, en ninfas originadas en verano y primavera. Las crías se realizaron en dos localidades: Corrientes y Santa Fe, utilizando ninfas recién eclosionadas en campo, criadas individualmente en recintos cerrados bajo influencia del clima local y sin exposición solar directa. En ambas localidades, los machos presentaron cinco estadios ninfales; las hembras cinco o seis. Las hembras con seis estadios fueron más frecuentes en las ninfas de verano. La mayor mortalidad de ninfas se produjo en los dos primeros estadios. La mayor duración del desarrollo ninfal en las hembras estuvo determinada por aquellas de seis estadios. Estos resultados, y los de otros sitios de Sudamérica sobre el ciclo de vida de C. aquaticum muestran que al analizar el número de estadios y el desarrollo ninfal de un acridio conviene realizar crías en distintos lugares y en periodos cuando las ninfas de estadio I presentan mayor abundancia en las poblaciones naturales. Las diferencias en el ciclo de vida de C. aquaticum en ninfas nativas y en cuarentena muestran la importancia de considerar las particularidades del desarrollo ninfal en el área de distribución nativa y los factores climáticos implicados, como información valiosa ante su posible utilización en el control biológico de E. crassipes en áreas no nativasCornops aquaticum is a semiaquatic grasshopper that lives in close association with Pontederiaceae, especially the genus Eichhornia. In the native range of distribution of this grasshopper, there is only information about life history traits of populations from Brazil and Uruguay. So, the aim of this work was to assess the number of juvenile instars and duration of nymphal development of C. aquaticum in summer and spring nymphs from Argentinean populations. Wild newly emerged nymphs were individually reared in Corrientes and Santa Fe city under the influence of the local climate, without direct sun exposure. In both sites, nymphs showed males with five instars and females with five or six instars. Female with six instars was significantly more frequent in the summer nymphs. The highest mortality of nymphs occurred mainly in the first two instars. Nymphal development was significantly longer in nymphs from the summer peak than the spring peak. Longer duration of nymphal development in females than in males was determined by females with six juvenile instars. Our results, as well as the results obtained in other sites of South America about the life cycle of C. aquaticum, show that when the instar number and nymphal development are the life history traits desirable to study in a species, rearing should be carried out at several geographical sites of its distribution, and in the periods when new hatched nymphs have the peaks of highest abundance in wild populations. Different juvenile instars in native populations respect to quarantine populations of C. aquaticum show the importance to consider life history traits throughout the native range and the effect of environmental factors as useful information for the possible use of this grasshopper as a biological control agent of Eichhornia crassipes in non-native areas.Cornops aquaticumé um acrídeo semiaquático que vive em estreita associação com Pontederiáceas, especialmente do gênero Eichhornia. Nos seus limites de distribuição nativa, a informação existente relativa ao ciclo de vida esta referida a populações de Brasil e Uruguai. Neste trabalho se determinou o número de estágios ninfais e a duração do desenvolvimento ninfal de C. aquaticumna Argentina, em ninfas originadas no verão e primavera. As crias se realizaram em duas localidades: Corrientes e Santa Fe, utilizando ninfas recém-eclodidas em campo, criadas individualmente em recintos fechados sob a influência do clima local e sem exposição solar direta. Em ambas as localidades, os machos apresentaram cinco estágios ninfais; as fêmeas cinco ou seis. Fêmeas com seis estágios foram mais frequentes nas ninfas de verão. A maior mortalidade de ninfas se produziu nos dois primeiros estágios. A maior duração do desenvolvimento ninfal nas fêmeas esteve determinada por aquelas de seis estágios. Estes resultados, e os de outros lugares da América do sul sobre o ciclo de vida de C. aquaticum, mostram que ao analisar o número de estágios e o desenvolvimento ninfal de um acrídeo convêm realizar crias em distintos lugares e em períodos quando as ninfas de estágios I apresentam maior abundancia nas populações naturais. As diferenças no ciclo de vida de C. aquaticumem ninfas nativas e em quarentena mostram a importância de considerar as particularidades do esenvolvimento ninfal nos limites de distribuição nativa e os fatores climáticos implicados, como informação valiosa diante de sua possível utilização no controle biológico de E. crassipes em áreas não nativas.Fil: Capello, Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto Nacional de Limnologia (i); ArgentinaFil: Franceschini, Maria Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Centro de Ecologia Aplicada del Litoral (i); Argentina. Universidad Nacional del Nordeste; Argentin

Morphology of fruits, seeds and embryos of Argentinian Capparis L. (Capparaceae)

Embryos, seeds and fruits of four species of Capparis L. (Capparaceae) from Argentina are described in this paper: C. flexuosa (L.) L. sensu lato, C. refusa Griseb., C. speciosa Griseb. and C. tweediana Eichl. Chlorophyllous embryos are found in C. flexuosa and C. retusa, species with thin seed coats, dehiscent siliques, and somewhat fleshy red endocarps. Nonchlorophyllous embryos are found in the berry-fruited C. speciosa and C. tweediana, the former with leathery indehiscent fruit wall, the latter with thin-walled dehiscent berries with massive fleshy pulp. The pulp is permeated by seed coat hairs in C. tweediana. The embryos of C. flexuosa, C. retusa and C. tweediana belong to the 'Axile Division, Foliate Subdivision, and Folded Type' of the classification devised by A. C. Martin in 1946. Some features of the embryo of C. speciosa (which are not considered in Martin's classification), support a new subdivision (Massive) and a new morphological type (Unequal cotyledons), characterized by profound anisocotyly, globose shape of the major cotyledon, presence of suberized cells and an undeveloped radicle. Anatomical studies of embryos and seedlings confirm the anisocotylyFil: 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; ArgentinaFil: Tressens, Sara Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentin