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Cova L.J.,University of Los Andes, Venezuela | Scorza D. J.V.,University of Los Andes, Venezuela | Garcia D.E.,Instituto Nacional Of Investigaciones Agricolas | Canizalez L.M.,Nucleo Universitario Rafael Rangel | And 3 more authors.
Zootecnia Tropical | Year: 2010

In order to determine the effectiveness of Beauveria brongniartii spores (Monilia: Moniliaceae) to control common flies (Musca domestica L.) through mist in the interior of sheds breeding chickens (7 chickens/m2), at doses of 9 × 107 conidias/mL (15 l prepared for each 1200 m2), an experiment was conducted in poultry units located in the vicinity of Isnotú, "Rafael Rangel" municipality, Trujillo state, Venezuela. At the start of the trial no difference in the average population of flies among the control and treated sheds were observed (P>0,05). However, statistical differences among control and treated sheds in the second (P<0,05), third (P<0,01) and fourth (P <0,001) weeks after first application were observed. The percentage of population reduction was prompted after nebulizer once a week for three weeks, 81, 31 and 100%, respectively. Results showed that under the experimental conditions B. brongniartii constitutes a viable alternative for comprehensive health control in the production units.

Pena A.,Nucleo Universitario Rafael Rangel | Alarcon L.,Nucleo Universitario Rafael Rangel | Baptista J.G.,Nucleo Universitario Rafael Rangel | Aparicio R.,University of Los Andes, Venezuela | And 2 more authors.
Avances en Quimica | Year: 2012

Espeletia nana Cuatrec is a resinous plant, member of the Espeletiinae Subtribe. It is a small size frailejón, 25cm high, found at Páramo Ortiz, Trujillo State, Venezuela. Leaves and roots were separately extracted with a 3:1 mixture of hexane-diethyl ether. Aliquotes of the acidic fractions were methylated and inspected by GC-MS. It was found that the resin from the leaves contained kaurenic acid (1a, 34.6%), grandiflorenic acid (2a, 40.1%), 15α-ent-acetoxy-kaur-16-en-19-oic acid (3a, 8%), and 15α-hidroxy-ent-kaur-16-en-19-oic acid (3a, 13%). The roots acid fraction contained 38% 1a, 39,6% 2b, 8.5% 3a, and 13.9% 4a. The GC-MS analysis of the leaves neutral fraction yielded 43% kaurenal (5), 3% kaurenol (6), 13% ruilopeziol (7a), 7% epi-ruilopeziol, 25% of nonacontane and 8% of entriacontane. On the other hand the roots resin contained 88%, 5.7% of 6, 2.5% 7a, 1.0% 7b, but only 1.5% of waxes. The bulk extracts were submitted to flash chromatography, leading to the isolation of pure kaurenes which were identified by direct comparison with authentic samples.

Gonzalez L.A.,Autonomous University of Nuevo León | Gonzalez L.A.,Nucleo Universitario Rafael Rangel | Garcia G.P.,Autonomous University of Nuevo León | Oviedo M.,Nucleo Universitario Rafael Rangel | And 2 more authors.
Boletin de Malariologia y Salud Ambiental | Year: 2014

The biochemical and molecular mechanisms associated with resistance to deltamethrin were determined in female Aedes aegypti taken from different mosquito populations captured in Trujillo, Lara and Tachira states. Individuals from each population were subjected to 1 h of exposure to deltamethrin using the CK+++50 previously determined by the bottle bioassay. The mosquitoes were then placed in containers free from insecticide and separated into 4 phenotypes: mosquitoes that were not knocked down after 1 h of exposure, those that recovered 4 h after exposure, those that were still alive 24 h after exposure and those that were dead at 24 h. Each of the mosquitoes in these groups was then dissected to separate the head-thorax, and abdomen. Biochemical tests were performed on the head-thorax to determine the presence of resistance-related enzymes including: a- and ß-esterases, glutathione S-transferase and insensitive acetylcholinesterase. The abdomen was used for molecular tests to amplifly the specific allele Val 1016 and Ile 1016. The quantities of detoxifying enzymes increased between 4 and 24 h after exposure to deltamethrin in mosquitoes from most of the populations tested although no significant differences between these and the susceptible New Orleans strain (NO) were found, except for mosquitoes from the Ureña population which showed a significant increase in ß-esterase with higher values in the "survivors" phenotype compared to the "dead" phenotype at 24 h. The wild genotype V1016/V1016 prevailed over the heterozygous and homozygous mutants in the four phenotypes in the majority of the populations studied, with exception of the Ureña population where the resistant homozygote I1016/I1016 was the predominant genotype. The V1016I mutation was associated with the knockdown resistance observed in the evaluated populations emphasizing the importance of the early detection of this and other mutations in the sodium channel which have been linked with resistance to pyrethroids. These aspects should be considered before applying deltamethrin to control these Ae. Aegypti populations.

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