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Search Results: 1 - 10 of 53140 matches for " Gorla David "
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Variables ambientales registradas por sensores remotos como indicadores de la distribución geográfica de Triatoma infestans (Heteroptera: Reduviidae)
Gorla,David E;
Ecolog?-a austral , 2002,
Abstract: the paper presents an analysis of the geographic distribution of triatoma infestans based on biophysical variables recorded by meteorological satellites. the analysis includes data derived from a temporal fourier analysis of monthly images over a set of 14 derived statistical descriptors of the average, minimum, maximum, variability, amplitude and phase of the air temperature, land surface temperature, medium infrared radiation and a vegetation index remotely sensed by the avhrr. temporal series covered the period 1982-2000, and the area from panamá to tierra del fuego. the analysis of individual variables showed that the annual phase of the normalised difference vegetation index identifies correctly 80% presence and absence sites of triatoma infestans. the analysis confirms the importance of temperature (especially air temperature) for triatoma infestans distribution, as 7 (out of 14) statistical descriptors associated with air temperature identified correctly >70% of presence and absence sites. a stepwise linear discriminant analysis showed that a function with six statistical descriptors (four of them associated with air temperature, one associated with medium infrared radiation, and one with the vegetation index) identified correctly 90% of presence and absence sites of triatoma infestans. the analysis shows the important association between the environmental variables studied at the continental scale and the distribution of a strictly domestic and haematophagous species. the approach could be useful for large scale studies of the distribution of other species with more direct and causal relation with vegetation and climate than triatoma infestans.
Second Law Analysis of a non-Newtonian Laminar Falling Liquid Film Along an Inclined Heated Plate
Rama Subba Reddy Gorla,David M. Pratt
Entropy , 2007, DOI: 10.3390/e9010030
Abstract: The second law analysis of heat transfer of a non-Newtonian, laminar fallingliquid film along an inclined heated plate is investigated. The upper surface of the liquidfilm is considered free and adiabatic. Velocity and temperature profiles are obtainedanalytically and used to compute the entropy generation number (N s), irreversibility ratio (Φ) and the Bejan number (Be) for several values of the viscous dissipation parameter(Br -1), viscosity index (n) and the dimensionless axial distance (X). The Bejan numberincreases in the transverse direction and decreases as the viscous dissipation parameter(BrΩ -1) increases. The numerical results show that the Bejan number decreases as theviscous dissipation parameter (BrΩ -1), Peclet number (Pe) and the viscosity index (n)increase.
Eficiencia de captura de adultos de Lepidoptera plagas de maíz (Zea mays) y de soja (Glicine max) en trampas de luz de vapor de mercurio y de luz negra en la región central de la provincia de Córdoba (Argentina)
Sagadin,Ileana M; Gorla,David E;
Ecolog?-a austral , 2002,
Abstract: the larvae of lepidoptera are very important crop pests in central córdoba province (argentina), because of the yield losses they produce on corn and soybean. we compared the efficiency of two light traps, one with a 125 w mercury vapour lamp hpl type and other with a 15-w blacklight lamp. moth catches were counted 1-3 times/week, from december 1997 to december 2000. the comparison of trap efficiency for each species was carried out with the slope of the relationship between week catches obtained for each trap. the mercury vapour trap was more efficient for most of the species, with some variations depending on the period that was analysed. there were no significant differences between traps for agrotis malefida and agrotis ipsilon, and the blacklight trap was more efficient for helicoverpa zea, spodoptera frugiperda and spilosoma virginica. for 8 out of the 18 collected species the efficiency of the traps depended on the species density.
Variación geográfica de la abundancia poblacional de Delphacodes kuscheli (Fennah) en la región central de Argentina
Grilli,Mariano P; Gorla,David E;
Ecolog?-a austral , 2002,
Abstract: delphacodes kuscheli is the vector of the río cuarto corn disease, which affects maize in central argentina. this disease is endemic of rio cuarto department in córdoba province. preliminary studies indicate that the insect is present in córdoba, la pampa, san luis, santa fe and buenos aires provinces, but there are few studies on the abundance in these places. previous research showed that delphacodes kuscheli arrives to maize plots from distant sources, and that there is a difference in the abundance of delphacodes kuscheli in the endemic area and outside it. in this work we study the geographic variations of the population abundance of delphacodes kuscheli along a transect that crosses the endemic area to verify whether there is a difference between the vector population dynamics within and outside the endemic area. samples of dispersing individual were collected during three years by using sticky traps at two different heights. the samples were taken in eight sampling sites between the localities of manfredi (córdoba) and mercedes (san luis). dispersive individuals of delphacodes kuscheli were more abundant in the endemic area than outside it. the dispersive population captured with low traps had a higher proportion of females, but there were no differences at high traps. the correlation of density changes observed in high traps decreased with distance between sampling sites, but there was no relationship for low traps. it is discussed how these results could indicate that delphacodes kuscheli is a species highly adapted to live in unstable habitats.
Experimental evaluation of insecticidal paints against Triatoma infestans (Hemiptera: Reduviidae), under natural climatic conditions
Ivana Amelotti, Silvia S Catalá, David E Gorla
Parasites & Vectors , 2009, DOI: 10.1186/1756-3305-2-30
Abstract: The study was based on an experimental design that included two groups treated with an organophosphate (Inesfly 5A IGR?) and a pyrethroid (Inesfly 5A IGR NG?) formulations of the paint, that were applied on wood, cement blocks and adobe bricks under natural climatic conditions. A third group was an untreated control. Both paint formulations showed very long residual activity, producing mortality of 84% and 98% (pyrethroid and organophosphate formulations, respectively) after 12 months of the paint application. After eight months, nymphs exposed during 6 hours to the painted surfaces with the pyrethroid and organophosphate formulations showed 81.33% and 100% mortality, respectively.The organophosphate- and pyrethroid-based insecticidal paints showed a very long residual activity on the mortality of fourth instar nymphs of T infestans, compared with the traditional spraying technique used for the application of pyrethroid insecticides in peridomestic structures of rural houses in the endemic region for Chagas disease in the Gran Chaco of Argentina. The application of the paints by trained personnel of the vector control programmes could be considered as an alternative control tool in areas where the traditional methods have failed or showed low efficacy.Chagas disease or American trypanosomiasis, is an infectious disease caused by Trypanosoma cruzi, transmitted by hematophagous insects of the subfamily Triatominae (Reduviidae). The disease is a major public health concern in Latin America, with estimates of 50000 people dying each year, 10 million people being infected, and around 100 million people being reportedly at risk of infection [1]. Although the disease is endemic in Latin American countries, human migration has spread the disease to other continents, especially North America and Europe [2,3]. In spite of long-term research efforts, there is no available vaccine [4] and treatment after infection is effective only for recent infections [5-7]. The preventive ap
Response of Triatoma infestans to pour-on cypermethrin applied to chickens under laboratory conditions
Amelotti, Ivana;Catalá, Silvia S;Gorla, David E;
Memórias do Instituto Oswaldo Cruz , 2009, DOI: 10.1590/S0074-02762009000300014
Abstract: this article reports the effects of a pour-on formulation of cypermethrin (6% active ingredient) applied to chickens exposed to triatoma infestans, the main vector of chagas disease in rural houses of the gran chaco region of south america. this study was designed as a completely random experiment with three experimental groups and five replicates. third instar nymphs were fed on chickens treated with 0, 1 and 2 cc of the formulation. nymphs were allowed to feed on the chickens at different time intervals after the insecticide application. third-instar nymphs fed on treated chickens showed a higher mortality, took less blood during feeding and had a lower moulting rate. the mortality rate was highest seven days after the insecticide solution application and blood intake was affected until 30 days after the application of the solution.
The residual efficacy of a cypermethrin pour-on formulation applied on goats on the mortality and blood intake of Triatoma infestans
Amelotti, Ivana;Catalá, Silvia Susana;Gorla, David Eladio;
Memórias do Instituto Oswaldo Cruz , 2012, DOI: 10.1590/S0074-02762012000800008
Abstract: triatoma infestans is the main vector of trypanosoma cruzi, the aetiological agent of chagas disease in the gran chaco region of south america. as a frequent blood meal source for triatomine bugs, domestic goats play a key role in the eco-epidemiology of chagas disease. the aim of this study was to evaluate the mortality and blood intake of t. infestans fed on goats that had been treated with different doses of pour-on insecticide. third-instar nymphs were fed on goats that had been treated with 0 cc, 5 cc, 10 cc or 15 cc of a pour-on formulation of cypermethrin. the exposure of t. infestans to animals treated at different post-application intervals revealed a residual activity of the insecticide. the mortality rate in the treated groups was higher than in the control groups until 30 days post-insecticide application (p = 0.03), except in the group treated with 5 cc, in which no mortality was detected after seven days of insecticide application. rainfall affected the triatomicide effect, reducing the time of residual activity. the cypermethrin pour-on treatment decreased the blood intake of t. infestans. thirty days after the cypermethrin application, nymph mortality was 16% (± 13) with both doses (10 cc and 15 cc). the 15 cc dose did not result in higher insect mortality or increased persistence compared to the 10 cc dose.
Dispersal of Triatoma infestans and other Triatominae species in the arid Chaco of Argentina: Flying, walking or passive carriage? The importance of walking females
Abrahan, Luciana Beatriz;Gorla, David Eladio;Catalá, Silvia Susana;
Memórias do Instituto Oswaldo Cruz , 2011, DOI: 10.1590/S0074-02762011000200019
Abstract: the aim of this paper was to analyse the active dispersal of triatoma infestans and the role of chickens as passive carriers of this insect in peridomestic areas of la rioja, argentina. to measure active dispersal, monthly catches were made on six consecutive nights for five months (in the warm season) using light traps (for flying insects) and sticky dispersal barriers (for walking insects). the nutritional and reproductive states of adults were evaluated. over the course of the sampling period, a total of eight flying adults, six walking nymphs and 10 walking adults of the species t. infestans were captured, as well as specimens of triatoma guasayana, triatoma eratyrusiformis and triatoma platensis. our data demonstrate for the first time that females of t. infestans can disperse by walking. this may be an adaptive strategy because it allows them to move with eggs and/or with good blood reserves, which are not possible when flying. all flying and walking individuals of both genders were of an appropriate physiological state that would allow for colonisation of the target habitat. however, manual inspection of 122 chickens suggests that it is unlikely that these animals passively transport t. infestans. finally, the dispersal activity of t. infestans was compared with other triatomines using a dispersion index.
Daily pattern of flight activity of Aedes albifasciatus in Central Argentina
Ludue?a Almeida, Francisco F.;Gorla, David E.;
Memórias do Instituto Oswaldo Cruz , 1995, DOI: 10.1590/S0074-02761995000500020
Abstract: aedes albifasciatus is an important common mosquito in central argentina. its a confirmed vector of the western equine encephalitis and is responsible for loss of milk production in dairy cattle during peak populations. this paper reports the flight activity pattern of ae. albifasciatus for different seasons, in the southern coast of the mar chiquita lake (central argentina). data were collected by sampling two sites between 1992 and 1993 with cdc traps and human-bait captures. adult mosquito population density, estimated by cdc trapping and human-bait, were highly correlated. however, when compared to other species, the proportion of ae. albifasciatus was higher in human-bait collections. adult female populations were active only when temperature were higher than 6§c. two daily biting peaks were observed (dusk and dawn) during the spring, summer and autumn, and only one peak during winter (around 15:00 pm). adult abundance was significantly correlated (r2= 0.71; p<0.01) with temperature and illumination.
The biology of Aedes (Ochlerotatus) albifasciatus Macquart, 1838 (Diptera: Culicidae) in Central Argentina
Ludue?a Almeida, Francisco F.;Gorla, David E.;
Memórias do Instituto Oswaldo Cruz , 1995, DOI: 10.1590/S0074-02761995000400006
Abstract: aedes albifasciatus is a flood water mosquito ocurring in the southern countries of south america. it is a competent vector of the western equine encephalitis (wee) and causes important losses on milk and beef production in central argentina. field work was carried out from december 1990 to march 1993, on a monthly basis during the dry season and biweekly during the rainy season. larvae were collected using the 'dipping' technique and females with cdc traps baited with co2. field collected larvae were used to build laboratory cohorts, from which basic population parameters were estimated. eggs survived up to six months on dry soil, although there was a linear decrease of viability with time. at 23oc, larval development time was around nine days, and all adults emerged within one week. the estimation of larval development in the laboratory seems to be very near the development on the field, as larvae have been collected on average eight days after a rainfall. egg to adult survival was 83%, with the highest mortality on fourth larval instar (6%). in the laboratory studies, sex proportion among the adults was 1:1, females lived longer than males (median 13 and five days, respectively), and adult survival pattern showed a constant number of individuals dying per unit time. field collected females layed an average of 84 eggs per batch, and completing up to five gonotrophic cycles, suggesting an estimated survival of up to 35-50 days.
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