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Valle de La Pascua, Venezuela

Trujillo I.,University Simon Rodriguez | Rivas M.,Simon Bolivar University of Venezuela | Castrillo M.,Simon Bolivar University of Venezuela
Journal of Plant Interactions | Year: 2013

Our hypothesis was that recovery responses (RI and RII) upon rehydration, after 1 and 8 d of moderate (WDI) and severe water deficit (WDII), are evidence of tolerance in two commercial bean cultivars, Tacarigua (T cv) and VUL-73-40 (V cv). Recovery of leaf water (Ψw) and osmotic potentials (Ψs), and relative water content (LRWC), showed strong dependence on soil water potential (sΨw) followed by protein content; recovery connection between stomatal conductance and soil Ψw is showed. Chlorophyll (a + b), Ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco) activity, dry biomass (DM), and leaf area (LA) recovery were sensitive to WD intensity. Specific leaf area (SLA) and leaf density (D) recovery were less dependent on WD intensity and in time-dependent manner; V cv recovery was slower, showed faster recovery of Rubisco activity and DM due to slower recovery in SLA and D, which promoted it. Rubisco activity presented correlations with LRWC and Ψw at moderate and severe WD in both cultivars, and significant correlation with Ψs was observed in V cv. We conclude that recovery after rehydration reveals intrinsic tolerance to WD, due to an integration of metabolic and structural interactions, in responses to leaf water status components. © 2013 Copyright Taylor and Francis Group, LLC.

Velazquez J.,Francisco de Miranda National Experimental University | Garcia J.L.,University Simon Rodriguez | Romero Y.,Francisco de Miranda National Experimental University | Medina M.,Francisco de Miranda National Experimental University
Entomotropica | Year: 2010

A research was carried out for the identification and the determination of some aspects of the biology and the natural control of a lepidopteran larva that causes damage in the inflorescences, bulbs and leaves of Agave cocui. Between April 2001 and April 2008 visits were carried out to areas with high density of A. cocui in Falcon State, and infested vegetable material was collected and brought to the laboratory where the damaging lepidopteran and its natural ennemies were reared under semi-controlled conditions, at a temperature 27 ± 3°C, relative humidity of 70 ± 8 % and a photoperiod 12:12. Duration of different phases and the number of larval instars were determined and the number of eggs produced per female, as well as the identification of the main natural enemies, were established. For the first time in Venezuela, Phidotricha erigens Ragonot, 1888 (Lepidoptera: Pyralidae) is mentioned as a plague of A. cocui. The adults passed average of 6.2 days (male) and 5.9 days (female), females placed an average of 18.5 eggs. The larvae hatch in about 4.2 days, they pass through five stadiums with a duration of 3.8, 3.7, 3.8, 5.4 and 5.5 days for the I, II, II, IV, and V instar respectively, being the average duration larval phase 19.7 days, and pupae 11.2 days. P erigens is controlled naturally by the parasitic hymenopterans, Apanteles sp., Copidosoma sp., Eiphosoma sp., Hymenochaonia sp. and Euplectrus sp. We detected Bramesa sp. and Perilampus sp. emerging from the pupae of Apanteles sp. © 2010, Sociedad Venezolana de Entomología.

The aim of this study was to perform a comparative study of the total number of leukocytes (TLN) and total serum proteins (TSP) in. Bos Taurus calves splenectomized vs non splenectomized, to serve as multipliers haemotropic agents. Six were splenectomized for conventional surgical methods and the remaining three were used as controls. The variables determinations were carried out during an experimental lapse of five weeks, using the hemocytometer for the obtaining of the TLN and commercial colorimetric method for analysis of SPT and its components (albumin, globulins and ratio A:G). The data grouped in means and they were analyzed of the non-parametric "U" Mann-Whitney. The comparison between means did not show any statistical differences. The findings did not allow definitive conclusions about variables studied. The ratio A:G (0.6) suggested the production of antibodies in animals splenectomized.

In the six species of fairy shrimps (Anostraca) recorded in Venezuela, only a few life history parameters have been determined for Dendrocephalus geayi y Thamnocephalus venezuelensis. The species Dendrocephalus spartaenovae Margalef, 1961 has a high potential as live food and for industrial purposes, and could be an alternative to Artemia cysts, which are expensive and sometimes hard to find. The objective of this study was to generate information about the nutritional behavior of D. spartaenovae in laboratory conditions and closed systems. Filtration and ingestion rates were determined in different concentrations of a mixed culture of the unicellular algae Pseudokirchneriella subcapita (Printz, 1914) y Chlorella vulgaris Beijerinck, 1980 on three animal groups aged 3-4, 10-11 and 17-18 days old. The filtration and ingestion rates were determined according to sex, animal density and light conditions on organisms 17- 18 days old fed with 5·105 cel/ml. Filtration rates decreased as the amount of food increased; while ingestion rates showed an inverse response. Sex conditions in older animals did not affect filtration and ingestion rates. The filtration rates did not show significant differences with regard to light conditions, but the highest food consumption (2,761,574 cel/ind/h) was recorded during the day and the lowest (1,465,278 cel/ind/h) at nighttime. Population densities over 2 ind/200ml caused a detriment in the nutritional behavior.

We describe a new species of Isolia Förster. Isolia santosi sp. n. is described on the basis of 166 specimens collected at the Parque Natural de Sant Llorenç del Munt i Serra de l'Ibac, (Catalonia, Spain). Diagnostic characters are given that set this species apart form other in the genus.

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