Surveillance and control of Aedes aegypti in Uruguay, achievements and challenges

Uruguay has monitored the presence of Aedes aegypti since 1997, when its reintroduction was reported. Since then, different methodologies have been used (larval surveys, control of strategic points, method of rapid survey of Aedes aegypti indices, traps). The LIRAa methodology is effective in detecting the main containers that are acting as breeding sites for Ae. aegypti in a certain area. However, the larval indices obtained are not sufficient to estimate the risk of arbovirus transmission because they do not provide a reliable estimate of the adult population, they do not take into account the distribution in transmission clusters and are heavily operator-dependant. The objective of this work was to improve the surveillance system in order to identify sites and periods with high Aedes density and help prevent future outbreaks of arbovirosis.Sociedad Latinoamericana de Ecología de Vectore

Aquatic insects that colonize environments created by man in Uruguay

El presente estudio se realizó en el marco del “Plan Nacional de Detección y Control de Aedes aegypti (Linnaeus, 1762) en Uruguay”, desde 1997 a 2012. Se documentó la diversidad de los insectos acuáticos que se hallaron en recipientes artificiales y desagües domiciliarios en Uruguay, detallando los distintos tipos de recipientes colonizados y la entomofauna acuática asociada. Se registraron cinco órdenes: Diptera, Ephemeroptera, Odonata, Hemiptera y Coleoptera. Los dípteros fueron los más diversos y estuvieron representados por nueve familias: Ceratopogonidae, Chironomidae, Corethrellidae, Culicidae, Ephydridae, Phoridae, Psychodidae, Syrphidae y Tipulidae. Las especies identificadas fueron: Dasyhelea necrophila Spinelli & Rodriguez, 1999, Chironomus (Chironomus) calligraphus Goeldi, 1905, Corethrella sp., complejo Megaselia imitatrix, Clogmia albipunctata (Williston, 1893), Psychoda (Tinearia) alternata Say, 1824, Psychoda cinerea Banks, 1894, Callibaetis sp., Sigara sp., Buenoa sp., Notonecta sp., Liodessus sp., Rhantus sp. y Thermonectus sp. En este trabajo no se incluyen las especies de Culicidae que ya fueron presentadas en una publicación previa.This study was conducted under the «National Plan of Detection and Control of Aedes aegypti (Linnaeus, 1762) in Uruguay,» from 1997 to 2012. Diversity of aquatic insects found in artificial containers and householdvdrains in Uruguay is documented. Different types of containers used as breeding sites and their associated aquatic fauna is detailed. Five orders were collected: Diptera, Ephemeroptera, Odonata,12 Insectos acuáticos en recipientes artificiales en Uruguay Hemiptera and Coleoptera. Dipterans were the most diverse, represented by nine families: Ceratopogonidae, Chironomidae, Corethrellidae, Culicidae, Ephydridae, Phoridae, Psychodidae, Syrphidae and Tipulidae. The species identified were: Dasyhelea necrophila Spinelli & Rodriguez, 1999 Chironomus (Chironomus) calligraphus Goeldi, 1905, Corethrella sp., complex Megaselia imitatrix, Clogmia albipunctata (Williston, 1893), Psychoda (Tinearia) alternata Say, 1824, Psychoda cinerea Banks, 1894, Callibaetis sp., Sigara sp., Buenoa sp., Notonecta sp., Liodessus sp., Rhantus sp. and Thermonectus sp. In this paper Culicidae species are not included because they were presented in a previous publication

Reduction of the frequency of herbaceous roots as an effect of soil compaction induced by heavy grazing in rangelands of SW Spain

Rangelands in SW Spain constitute the most extensive ranching system on the Iberian Peninsula. During the last few decades, a significant increase in livestock numbers, along with a progressive substitution of cattle for sheep, have led to land degradation processes such as the reduction of grass cover and increased soil compaction in heavily grazed areas. Nevertheless, a better understanding of how soil compaction affects grass production is still needed. In this study, some of the effects of soil compaction due to heavy grazing are analysed, mainly the reduction of the frequency of herbaceous roots and its relationships with bulk density and soil penetration resistance. The study was carried out in 22 fenced areas grazed under different intensities (animal stocking rates: 0.19-15.76 AU ha−1). Undisturbed soil core and bulk samples were collected at 3 depth intervals in order to determine select soil properties (texture, organic matter content, and bulk density). Additionally, soil penetration resistance was quantified at 890 random points at different depths and soil moisture contents. Frequency of herbaceous roots was estimated for each soil horizon in 47 soil profiles and categorized into 4 classes: none, few, common and many. Results showed negative relationships between bulk density (> 10 cm depth) and the content of soil organic matter from 0 to 5 cm (r =−0.061, p < 0.05) and 5-10 m depth (r = −0.824, p < 0.005). Furthermore, a tendency for decreasing mean values of soil penetration resistance as the frequency of herbaceous roots increased was also observed. The values observed confirm that soil compaction provoked by an excessive number of animals reduced the quantity of herbaceous roots. The value of 2 MPa traditionally accepted as restrictive for root growth is discussed. Findings presented here could be of interest for policy makers and farm owners to guide decisions about optimum animal stocking rates