SUMMARYIn Uruguay, many beekeepers transport their colonies to Eucalyptus grandis plantations at the end of the summer and autumn, obtaining important honey harvests. However, at the end of the flowering period the colonies become extremely weakened undergoing high levels of mortality. Nutritional and health problems could explain the weakening of colonies. In order to find out the causes for this weakening, colonies of the same size were taken to an E. grandis plantation, split up in three groups differentiated by the availability of pollen. Throughout the flowering period we registered: the botanical origins and crude protein content of the incoming pollen, the body protein of the bees, the infection by Nosema ceranae and the infestation of Varroa destructor, the brood area and the production of honey. The most important findings were: i) the sustained decline in botanical diversity of pollen as the flowering period of E. grandis advanced until only pollen from this species remained; ii) pollen from E. grandis presented crude protein values close to 30%, but these gradually diminished reaching values lower than 20% towards the end of the flowering period; iii) those colonies which initially counted on pollen reserves presented bees with higher body protein a few days after settling in the plantation and lower levels of infection with N. ceranae during most of the flowering period; iv) pollen availability did not affect levels of infection by V. destructor, size of the brood area or honey production. Bee's nutritional deficit during E. grandis flowering could generate adequate conditions for the multiplication of N. ceranae. At the end of the Eucalyptus' flowering period colonies presented on average more than 90% of foraging workers infected with N. ceranae and 12% infection of adult bees with V. destructor. Incidence of both pathogens in weakened bees could explain colony losses.
RESUMENEn Uruguay muchos apicultores trasladan sus colonias a las forestaciones de Eucalyptus grandis al final del verano y en otoño obteniendo importantes cosechas de miel. Sin embargo, cuando finaliza la floración las colonias se encuentran muy debilitadas, sobreviniendo una elevada mortalidad. Problemas nutricionales y sanitarios podrían explicar el debilitamiento de las colonias. Para averiguar las causas del debilitamiento se llevaron colonias de igual tamaño a una forestación de E. grandis, separadas en tres grupos diferenciados por la disponibilidad de polen. A lo largo del periodo de floración se registró: el origen botánico y el contenido de proteína cruda del polen que ingresaba en las colmenas, la proteína corporal de las abejas, la infección por Nosema ceranae y la infestación por Varroa destructor, el área de cría y la producción de miel. Los resultados más importantes hallados fueron: i) la sostenida disminución de la diversidad botánica del polen a meArchivos de zootecnia vol. 60, núm. 232, p. 1304. INVERNIZZI, SANTOS, GARCÍA, DANERS, DI LANDRO, SAADOUN AND CABRERA dida que transcurría el periodo de floración de E. ...
IntroducciónLos quistes de dinoflagelados de pared orgánica muestran un alto potencial tanto en la resolución de problemas estratigráficos como en las reconstrucciones paleoambientales. Esto ha promovido un gran desarrollo de la palinología marina en las últimas décadas, en particular el estudio de las asociaciones del Paleógeno y la utilización de los quistes de dinoflagelados como indicador indirecto (proxy-data) en el análisis detallado de la transición desde el modo climático invernadero al modo glacial (Sluijs et al., 2005;.En los últimos años se ha incrementado notablemente el estudio de dinoflagelados en varias localidades circum-antárticas (Brinkhuis et al., 2003a, AMEGHINIANA (Rev. Abstract. PALEOGENE DISTRIBUTION OF ENNEADOCYSTA (DINOFLAGELLATA) IN THE SOUTHWESTERN ATLANTIC OCEAN: PALEOCEANOGRAPHIC IMPLICATIONS. The study of Middle to Late Eocene dinoflagellate cyst assemblages from subtropical Southwest Atlantic basins shows the presence of species of Enneadocysta, including E. dictyostila (Menéndez) Stover and Williams emend. Fensome et al., E. brevistila Fensome et al. and E. multicornuta (Eaton) Stover and Williams. The species Enneadocysta dictyostila has been widely recorded in middle Paleogene sections from Southern Hemisphere high latitudes. High representativity of Enneadocysta spp., along with other components of the Southern Ocean endemic dinoflagellate flora, have been observed in samples from Colorado Basin (~38°S), Argentina and Punta del Este Basin (~36°S), Uruguay. Previous research in the Tasman area has related the presence of these endemic taxa at mid-latitudes to the formation of a strong clockwise subpolar gyre ("cold trap") favoured by the continental blockage of the Tasman Gateway. In this paper we propose that the observed dinoflagellate cyst distribution in the Southwest Atlantic basins can be explained by a similar dynamical mechanism operating close to the present Weddell Gyre. The blockage of the Tasman Gateway and a partially open Drake Passage both contributed to the formation of a strong western-intensified clockwise gyre that may have transported the endemic flora components, mainly represented by Enneadocysta spp., from the Antarctic continent northward along the Southwest Atlantic Shelf during the Middle -Late Eocene. Resumen. En las asociaciones de quistes de dinoflagelados del Eoceno medio a tardío de cuencas subtropicales del Atlántico Sudoccidental se registra la presencia de especies de Enneadocysta, entre ellas: E. dictyostila (Menéndez) Stover y Williams emend Fensome et al., E. brevistila Fensome et al. y E. multicornuta (Eaton) Stover y Williams. La especie Enneadocysta dictyostila fue registrada en secciones del Paleógeno medio de altas latitudes del Hemisferio Sur. Se hallaron numerosos ejemplares de Enneadocysta spp. junto con otros componentes de la flora de dinoflagelados endémica del Océano Austral en las cuencas del Colorado (~38°S), Argentina y Punta del Este (~36°S), Uruguay. Previamente, en un trabajo realizado en el área de Tasmania, otros autores r...
Bees (Family Apidae) hold a key role as pollinators in a wide range of angiosperm communities. South America suffered strong modifications during the last decade due to increasing anthropic activities and the expansion of agricultural areas, particularly the boom of soybean. The goal of this research was to know the current diversity of bees in South and Low Littoral regions in Uruguay. Specimens were collected in the seasons 2015–2016 and 2016–2017 on natural meadows, cultivated grasslands, soybean fields, among others flowering communities. Collected specimens were classified following taxonomic keys. Forty-five bee species or taxa were distinguished belonging to the subfamilies Megachilinae (11), Apinae (22), Halictinae (7), Colletinae (2), and Andreninae (3). Most taxa were classified up to genus and 14 to species level. Bee diversity was higher for the South region, with traditional agriculture and rangelands, than that of the Low Littoral region where an increasing agricultural land use took place during the last decade, particularly soybean. In addition, this research aimed to study the presence of native bees and the introduced Apis mellifera (Apinae) in a soybean field at four transects located at 0, 50, 100, and 200 m from the crop border in both seasons. Native bee species were only present at 0 and 50 m, pointing to the relevance of natural edge plant communities for their preservation. This is the first survey on native bee diversity in Uruguay to be regarded as a baseline and the setup of conservation strategies.
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