Host–parasite relationships and life cycles of cuckoo wasps in agro-ecosystems in Argentina (Hymenoptera: Chrysididae: Chrysidini)

Chrysididae is a diverse group of parasitoid/cleptoparasitic wasps; however, host– parasite relationships and life cycles of few species have been studied. Nests of different wasp and bee species were obtained during a trap-nesting programme, in the Pampean region. Some of these nests were parasitised by cuckoo wasps females of Caenochrysis taschenbergi (Mocsáry), Chrysis boutheryi (Brèthes), C. saltana Bohart, C. sp. 1 (ignita-group), C. sp. 2 (ignita-group), Neochrysis lecointei (Ducke), Pleurochrysis ancilla (Buysson) and P. lynchi (Bréthes). This paper reports new data about host–parasite relationships and life cycles for these species. Multiple parasites (from one species or from different families of insects) emerged from single cells of some parasitised nests: from each host cell parasitised by species of Pleurochrysis, two adults emerged successfully, information previously unknown for the genus; and in three cases of cells parasitised by C. boutheryi, two adults successfully emerged from a single cell; in two cases both individuals were chrysidine, and in third one was chrysidine and one Leucospis pulchripes (Leucospidae).Fil: Torretta, Juan Pablo. Universidad de Buenos Aires. Facultad de Agronomia. Cátedra de Botanica General; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Life cycle of Huarpea fallax (Hymenoptera: Sapygidae) in a xeric forest in Argentina

This study describes the life cycle of Huarpea fallax (Hymenoptera: Sapygidae) in a xeric forest in La Pampa province, Argentina. This cleptoparasitic wasp attacks the nests of two species of leaf-cutter bees: Megachile catamarcensis and Anthidium vigintipunctatum, both belonging to the family Megachilidae. Nests of these bee species were obtained during a trap-nesting programme. Adult emergence showed a unimodal pattern indicating a univoltine life cycle. The period from egg-laying to adult emergence lasted for 10–13 months; however, one female took about 2 years to emerge, suggesting parsivoltinism. Most females attack one cell per host nest, the outermost cells being the ones most parasitized. However, the position of the attacked cells was variable. In this paper, although there were insufficient data to prove a correlation, the data suggest a positive trend between body size of sapygid wasps and their host bees.Fil: Torretta, Juan Pablo. Universidad de Buenos Aires. Facultad de Agronomia. Cátedra de Botanica General; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

First report of Monoeca in Argentina, with description of two new species (Hymenoptera: Apidae)

Two new species of the oil-collecting bee genus Monoeca Lepeletier & Audinet-Serville (Apidae: Tapinotaspidini) are described and figured from females and males captured in north - eastern Argentina. The two new species here described, Monoeca armata Torretta & Roig-Alsina, new species, and M. puchella Torretta & Roig-Alsina, new species, are easily distinguished from each other by the color of the integument, the wings, and the pilosity. Their relationships to al - ready described species of the genus are discussed. Monoeca were the only genus of Tapinostaspi - dini not known to occur in Argentina. The flower records and the study of the pollen scopal loads corroborate the association of these oil-collecting bees with p lants of the family Malpighiaceae.Fil: Torretta, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Recursos Naturales y Ambiente. Cátedra de Botánica Agrícola; ArgentinaFil: Roig Alsina, Arturo Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales ; Argentin

New records of Messatoporus (Hymenoptera: Ichneumonidae) from Argentina, with comments on its biology

Se presentan nuevos registros del género Messatoporus Cushman de la Isla Martín García, Argentina, y se menciona por primera vez la especie Messatoporus transversostriatus (Spinola) de la Argentina. La especie fue criada de nidos de Isodontia costipennis (Spinola) (Sphecidae), Pachodynerus guadulpensis (Saussure) y Monobia angulosa Saussure (Vespidae). Estos registros constituyen las primeras observaciones biológicas detalladas para un miembro del género Messatoporus en la Región Neotropical y representan la primera asociación del género con nidos de Sphecidae.New records of the genus Messatoporus Cushman from Martín García Island, Argentina, are provided and the species Messatoporus transversostriatus (Spinola) is recorded for the first time from Argentina. This species was reared from nests of Isodontia costipennis (Spinola) (Sphecidae), Pachodynerus guadulpensis (Saussure) and Monobia angulosa Saussure (Vespidae). These records represent the first detailed biological observations for a neotropical species of the genus and are the first association of Messatoporus with sphecid nests.Fil: Martinez, Juan Jose. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Torretta, Juan Pablo. Universidad de Buenos Aires. Facultad de Agronomía. Cátedra de Botánica General; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Insects related with sunflower (Helianthus annuus L.) pollination in Argentina

En este trabajo se relevaron los visitantes florales del girasol en un amplio rango de su área de cultivo en Argentina. Se colectaron 73 especies de insectos diurnos pertenecientes a 7 órdenes. Los himenópteros fueron los más representados y los más abundantes visitantes florales. La abeja doméstica (Apis mellifera) fue el principal polinizador del cultivo en todos la mayoría de los estudiados. Se comprobó que esta especie remueve efectivamente granos de polen de los estambres y los deposita en los estigmas en sus visitas a los capítulos de girasol. Especies de abejas nativas, principalmente Melissodes spp. y Melissoptila spp. (Apidae, Eucerini) y Megachile spp. (Megachilidae), también visitaron a los capítulos pero debido a su menor abundancia su participación como polinizadores del girasol parece ser limitada. Gran cantidad de especies de insectos nocturnos (ca. 80 especies o morfoespecies en 4 órdenes, principalmente lepidópteros de la familia Noctuidae) visitaron al girasol durante las primeras horas de la noche, en un momento en que el estigma no se encuentra receptivo. Debido a esto, las interacciones del girasol con sus visitantes nocturnos parecen tener carácter antagónico en lugar de mutualístico. También se analizó la estructura de la red planta-polinizador que involucra al girasol y a la vegetación circundante a los lotes del cultivo. En todos los sitios relevados las malezas interactuaron con los principales visitantes florales del girasol. La bordura de malezas permite la supervivencia de gran cantidad de especies de insectos benéficos así como también constituye un refugio para numerosas especies de plantas nativas.Floral visitors to sunflowers heads were recorded over a wide range of the crop area in Argentina. Seventy-three diurnal insect species belonging to 7 orders were collected. Hymenoptera was both the most species-rich order and the most abundant group of floral visitors. The domestic bee (Apis mellifera) was the main crop pollinator at most of the eight studied sites. For this species, effective pollen grain removal from anthers and pollen deposition on sunflower stigmas was unequivocally demonstrated. Several native bee species, mainly Melissodes spp. and Melissoptila spp. (Apidae, Eucerini) and Megachile spp. (Megachilidae) visited the heads too, but they were far less abundant than the honeybee and therefore their share in sunflower pollinators seems to be limited. A high number of nocturnal insects (ca. 80 species or morphospecies in 4 orders, mainly noctuid moths) visited the heads at dusk, when the stigma is not receptive. These visitors consumed nectar and probably wasted pollen, therefore the interaction between the sunflower and its nocturnal visitors seems to have an antagonic, instead of mutualistic, character. The structure of the plant-pollinator network involving the sunflower and the vegetation strips which surround the sunflower fields was also analised. At all sites the weeds of the field borders interacted with the main floral visitors of the crop. Thus, the crop marginal vegetation allows for the survival of many benefitial insect species and at the same time it constitutes a refuge for many local native plants species.Fil: Torretta, Juan Pablo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Glyphosate commercial formulation negatively affects the reproductive success of solitary wild bees in a Pampean agroecosystem

Glyphosate is the most widely used herbicide worldwide and it could have negative effects on wild bees. We study the effect of glyphosate commercial formulation on the nesting behavior of wild solitary bees (Megachile spp.) and the survival of immature stages in a Pampean agroecosystem. In four plots without agricultural management located in an agricultural field, we placed 480 wooden trap-nests. The traps were sprayed with two different concentrations of glyphosate commercial formulation and only with water. The number of cells per nest was significantly lower in glyphosate treated traps compared with the water treatment. The probability of finding breeding cells was two times higher in nests without glyphosate commercial formulation compared with treated nests. Larvae completed their development and emerged as adults approximately four times more in nests without glyphosate commercial formulation, relative to those with glyphosate. Our results indicate that glyphosate commercial formulation could be conditioning the behavior of the nesting females and it is affecting their reproduction.Fil: Graffigna, Sofia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentina. Laboratorio de Interacciones Bióticas en Agroecosistemas; ArgentinaFil: Marrero, Hugo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina. Laboratorio de Interacciones Bióticas en Agroecosistemas; ArgentinaFil: Torretta, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario; Argentina. Universidad de Buenos Aires. Facultad de Agronomía; Argentin

The Sarcophagidae (Diptera) of the Coastline of Buenos Aires City, Argentina

Fil: Mariluis, Juan C. ANLIS Dr.C.G.Malbrán. Centro Nacional de Diagnóstico e Investigación en Endemo-Epidemias; Argentina.Fil: Schnack, Juan A. División Entomología, Museo de La Plata, Universidad Nacional de La Plata, La Plata; Argentina.Fil: Mulieri, Pablo R. ANLIS Dr.C.G.Malbrán. Centro Nacional de Diagnóstico e Investigación en Endemo-Epidemias; Argentina.Fil: Torretta, Juan P. Cátedra de Botánica Agrícola, Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires; Argentina.The flesh fly community was surveyed on the shoreline of Río de la Plata at an ecological reserve whose western border directly abuts downtown eastern Buenos Aires. Samples were taken at monthly intervals from September 2004 to August 2005. To attract the flies, dog faeces and rotten cow liver were used as bait. Overall number, species composition and sex ratio were referred to each chosen bait. Of the thirteen species captured during the sampling period, Helicobia aurescens (Townsend), Oxysarcodexia culmiforceps Dodge, Oxysarcodexia marina (Hall), Oxysarcodexia thornax (Walker), Sarcophaga (Lipoptilocnema) koehleri (Blanchard), S. (L.) lanei (Townsend) and Tricharaea (Sarcophagula) occidua (Fabricius) were recorded for the first time in Buenos Aires city. Regardless of species composition, higher number of flies were obtained on faeces. Tricharaea (S.) occidua, was highly dominant (78,35%) followed in abundance by Oxysarcodexia varia (7,82%), both species showing a strong preference for dog faeces. Microcerella muehni and Oxysarcodexia paulistanensis did not show any preference on either bait. Sex ratio was male biased for O. varia, while females were dominant for O. paulistanensis and T. (S.) occidua, and no differences were found for M. muehni. Bait's preference and sex ratio could not be estimated for the remaining species due to their low abundance

Invader complexes or generalist interactions? Seasonal effects of a disturbance gradient on plants and floral visitors

Fil: Agüero, Juan I. Universidad de Buenos Aires. Facultad de Agronomía. Cátedra de Botánica General. Buenos Aires, Argentina.Fil: Coulin, Carolina. Universidad Nacional de Río Negro. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural. Río Negro, Argentina.Fil: Coulin, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural. Río Negro, Argentina.Fil: Torretta, Juan P. Universidad de Buenos Aires. Facultad de Agronomía. Cátedra de Botánica General. Buenos Aires, Argentina.Fil: Garibaldi, Lucas A. Universidad Nacional de Río Negro. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural. Río Negro, Argentina.Fil: Garibaldi, Lucas A. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural. Río Negro, Argentina.Disturbances can facilitate the spread of exotic plants, which establish mutualisms with exotic bees, constituting invader complexes. However, a disturbance-mediated increase in flower resources can also promote native floral visitors due to the fact that plant-pollinator interactions are generalist. We experimentally tested these ideas in northern Patagonian woodlands. In three sites, we examined the effect of harvesting intensity (HI) (0%, 30%, 50%, 70% of biomass removal) on flower density (exotic: herbs; native: herbs, shrubs, trees) and floral visitor density (exotic: honey bees, bumblebees; native: bees and wasps, hoverflies, other flies, beetles, ants). For four years, we made observations throughout the flowering period to test seasonality. HI had the most substantial positive effect on native herbs, followed by shrubs, and it was null on trees. The effects on the floral density of exotic herbs depended on site. HI enhanced the density of exotic bumblebees, native bees and wasps, and hoverflies; but it had no effect on honey bees, and it showed variable effects on the other floral-visitor groups. Although seasonality was relevant, there was no strong interaction with HI. In general, HI enhanced the density of native and exotic floral visitors, which is better explained by generalist interactions rather than by invader complexes.

Preys and capture sites used by crab spiders (Araneae: Thomisidae and Philodromidae) in a grassland of central Argentina.

La distribución de los depredadores y flores son factores importantes que influyen sobre la elección del sitio de forrajeo por los visitantes florales. Los depredadores como las arañas cangrejo pueden determinar la estructura de las comunidades de visitantes florales y afectar la polinización de las plantas. Los objetivos de este trabajo fueron (a) evaluar el uso por las arañas cangrejo de flores o inflorescencias (en adelante unidades de atracción floral, UAF) como sitios de captura; (b) determinar características que pueden afectar el uso de los sitios de captura; y (c) evaluar la relación entre el tamaño de las arañas y el de sus presas. Recorrimos dos parcelas de una hectárea en el centro de la región Pampeana (Buenos Aires, Argentina) registrando todas las plantas entomófilas en flor y sus visitantes florales. Además, capturamos todas las arañas cangrejo con y sin presa registrando las UAF que utilizaron como sitio de captura. Medimos y evaluamos la relación entre el tamaño de las arañas y de sus presas. Las arañas cangrejo utilizaron como sitios de captura las UAF más abundantes y con mayor riqueza de visitantes florales, independientemente de si eran flores o inflorescencias. Por otro lado, el tamaño de la araña podría determinar el tamaño de su presa. Encontramos una asociación positiva entre ambas variables, aunque este resultado fue variable dependiendo de los órdenes taxonómicos de las presas. Estos resultados sugieren que las arañas cangrejo pueden tener un papel relevante modelando la estructura de las interacciones planta-polinizadores.Distribution of predators and flowers influence on the selection of forage site of flower visitors. Predators, as crab spiders, can determine the structure of communities of flower visitors and influence on plant pollination. The objectives of this study were: (a) to evaluate the use of flowers or inflorescences (hereinafter units floral attraction, UFA) by crab spiders as capture sites; (B) to identify traits that may affect the use of capture sites; and (c) to assess the relationship between the size of the spiders and their prey. We surveyed two plots of one hectare in center of Pampas region (Buenos Aires, Argentina) recording all entomophilous flowering plants and their floral visitors. In addition, we captured all crab spiders with and without preys, recording the UFA they used as capture site. We estimate and evaluate the relationship between the size of the spiders and their prey. Crab spiders used as capture sites the most abundant UFA and with higher richness of floral visitors, regardless of whether they were flowers or inflorescences. On the other hand, the size of the spider could be determining the size of the preys. We found a positive association between the two variables, although this result was variable depending on the taxonomic orders of preys. Those results suggest that crab spiders can have a relevant role as modelers of the structure of plant - pollinator interaction.Fil: Marrero, Hugo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de Las Zonas Aridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de Las Zonas Aridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de Las Zonas Aridas; ArgentinaFil: Pompozzi, Gabriel Alejandro. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Laboratorio de Zoología de Invertebrados Ii; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Torretta, Juan Pablo. Universidad de Buenos Aires. Facultad de Agronomia. Cátedra de Botanica General; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Comparative anatomy of elaiophores and oil secretion in the genus Gomesa (Orchidaceae)

Oils are atypical floral rewards in Orchidaceae, and are produced by epidermal glands called elaiophores. Flowers of many members of the sub-tribe Oncidiinae either produce oil or mimic oil-producing flowers of Malpighiaceae. We focus our research on three species of Gomesa, namely, G. flexuosa, G. riograndensis and G. varicosa in order to investigate the presence of elaiophores, their micromorphology and internal structure and the process of oil secretion. Elaiophores were located using Sudan III, and their internal and external features examined using light and scanning electron microscopy, respectively. The presence of elaiophores was confirmed for regions of calli that are prominent and exposed. In all three species, the secretory tissue comprised a single layer of epidermal cells, together with some parenchymatous, subsecretory cells. Epidermal cells were isodiametric or palisade-like, with dense cytoplasm, small vacuoles and prominent nuclei. Gomesa flexuosa differs from the other species investigated in that it bears intermediate elaiophores (i.e. epithelial and possessing unicellular, secretory trichomes). Based on the absence of a distended cuticle, we propose that oil possibly passes through the wall and cuticle as small lipid moieties. In addition, some evolutionary trends in the elaiophores in the genus Gomesa are suggested.Fil: Gomiz, Natalia Elva. Universidad de Buenos Aires. Facultad de Agronomia; ArgentinaFil: Torretta, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion; ArgentinaFil: Aliscioni, Sandra Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion; Argentin