Daily survival rates and dispersal of Aedes aegypti females in Rio De Janeiro, Brazil

Laboratório de Transmissores de Hematozoários, Departamento de Entomologia, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil.
The American journal of tropical medicine and hygiene (Impact Factor: 2.7). 04/2007; 76(4):659-65.
Source: PubMed


Daily survival rates, life expectancy, dispersal, and parity are important components of vectorial capacity of Aedes aegypti. These parameters were estimated for mosquito populations from a slum and a suburban district in Rio de Janeiro, during the wet and dry seasons in 2005. In each mark-release-recapture experiment, three cohorts of dust-marked Ae. aegypti females were released. Recaptures were carried out daily in randomly selected houses, using backpack aspirators, adult traps, and sticky ovitraps. Recapture varied between 6.81% and 14.26%. Daily survival was estimated by fitting two alternative models: exponential and nonlinear models with correction for the removal of individuals. Slum area presented higher survival and parity rates (68.5%). Dispersal rates were higher in the suburban area, where a maximum dispersal of 363 m was observed. Results suggest intense risk of dengue epidemic, particularly in the urban area.

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    • "The BG-Sentinel trap (BGS) was developed at the University of Regensburg in Germany and attracts mosquitoes by simulating the odours and colouration of the host animal (Kroeckel et al. 2006). This device has proven to be relatively effective for the collection of African anophelines under semi-natural conditions (Schmied et al. 2008), as well as a number of other Culicidae in the field (Kroeckel et al. 2006, Maciel-de-Freitas et al. 2007, Williams et al. 2007). However, during preliminary field trials in 2005 in Porto Velho, in the Brazilian state of Rondônia (RO), the BGS was relatively ineffective for the collection of anthropophilic anophelines in general, and Anopheles darlingi in particular, of which only a single specimen was collected (unpublished observations). "
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    ABSTRACT: Although the human-landing catch (HLC) method is the most effective for collecting anthropophilic anophelines, it has been increasingly abandoned, primarily for ethical considerations. The objective of the present study was to develop a new trap for the collection of Anopheles darlingi . The initial trials were conducted using the BG-Sentinel trap as a standard for further trap development based on colour, airflow direction and illumination. The performance of the trap was then compared with those of the CDC, Fay-Prince, counterflow geometry trap (CFG) and HLC. All trials were conducted outdoors between 06:00 pm-08:00 pm. Female specimens of An. darlingi were dissected to determine their parity. A total of 8,334 anophelines were captured, of which 4,945 were identified as An. darlingi . The best trap configuration was an all-white version, with an upward airflow and no required light source. This configuration was subsequently named BG-Malaria (BGM). The BGM captured significantly more anophelines than any of the other traps tested and was similar to HLC with respect to the number and parity of anophelines. The BGM trap can be used as an alternative to HLC for collecting anophelines.
    Memórias do Instituto Oswaldo Cruz 09/2013; 108(6):763-71. DOI:10.1590/0074-0276108062013013 · 1.59 Impact Factor
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    • "The biological relevance of the reduction of oviposition success and fecundity in DENV-infected individuals might be limited for several reasons. First, Ae. aegypti daily survival rates in the field suggest that only a small number of mosquitoes would survive to reach the 3rd oviposition cycle, which is where we observed the strongest reduction in fecundity [39]. Additionally, because the incidence of DENV infection in natural mosquito population is extremely low, any differential effect on fecundity that DENV infection might impose on female mosquito is likely negligible. "
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    ABSTRACT: Background Aedes aegypti is the main vector of dengue, a disease that is increasing its geographical range as well as incidence rates. Despite its public health importance, the effect of dengue virus (DENV) on some mosquito traits remains unknown. Here, we investigated the impact of DENV-2 infection on the feeding behavior, survival, oviposition success and fecundity of Ae. aegypti females. Methods/Principal Findings After orally-challenging Ae. aegypti females with a DENV-2 strain using a membrane feeder, we monitored the feeding behavior, survival, oviposition success and fecundity throughout the mosquito lifespan. We observed an age-dependent cost of DENV infection on mosquito feeding behavior and fecundity. Infected individuals took more time to ingest blood from anesthetized mice in the 2nd and 3rd weeks post-infection, and also longer overall blood-feeding times in the 3rd week post-infection, when females were around 20 days old. Often, infected Ae. aegypti females did not lay eggs and when they were laid, smaller number of eggs were laid compared to uninfected controls. A reduction in the number of eggs laid per female was evident starting on the 3rd week post-infection. DENV-2 negatively affected mosquito lifespan, since overall the longevity of infected females was halved compared to that of the uninfected control group. Conclusions The DENV-2 strain tested significantly affected Ae. aegypti traits directly correlated with vectorial capacity or mosquito population density, such as feeding behavior, survival, fecundity and oviposition success. Infected mosquitoes spent more time ingesting blood, had reduced lifespan, laid eggs less frequently, and when they did lay eggs, the clutches were smaller than uninfected mosquitoes.
    PLoS ONE 03/2013; 8(3):e59933. DOI:10.1371/journal.pone.0059933 · 3.23 Impact Factor
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    • "aegypti trapped between August and September were parous [43]. The percent of parous females trapped in Tucson is much lower than recorded percentages in some dengue endemic regions such as Rio de Janeiro, Brazil (92.9%) [16], [17], and in Trinidad, West Indies (99%) [44]. A recent study conducted in dengue-free Al-Madinah, Saudi Arabia found parity rates as low as 29.1% [45]. "
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    ABSTRACT: Aedes aegypti, the primary vector of dengue virus, is well established throughout urban areas of the Southwestern US, including Tucson, AZ. Local transmission of the dengue virus, however, has not been reported in this area. Although many factors influence the distribution of the dengue virus, we hypothesize that one contributing factor is that the lifespan of female Ae. aegypti mosquitoes in the Southwestern US is too short for the virus to complete development and be transmitted to a new host. To test this we utilized two age grading techniques. First, we determined parity by analyzing ovarian tracheation and found that only 40% of Ae. aegypti females collected in Tucson, AZ were parous. The second technique determined transcript levels of an age-associated gene, Sarcoplasmic calcium-binding protein 1 (SCP-1). SCP-1 expression decreased in a predictable manner as the age of mosquitoes increased regardless of rearing conditions and reproductive status. We developed statistical models based on parity and SCP-1 expression to determine the age of individual, field collected mosquitoes within three age brackets: nonvectors (0-5 days post-emergence), unlikely vectors (6-14 days post-emergence), and potential vectors (15+ days post-emergence). The statistical models allowed us to accurately group individual wild mosquitoes into the three age brackets with high confidence. SCP-1 expression levels of individual, field collected mosquitoes were analyzed in conjunction with parity status. Based on SCP-1 transcript levels and parity data, 9% of collected mosquitoes survived more than 15 days post emergence.
    PLoS ONE 10/2012; 7(10):e46946. DOI:10.1371/journal.pone.0046946 · 3.23 Impact Factor
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