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As a result of numerous successful invasions by both Aedes albopictus (Skuse) and Ades aegypti (L.), the current worldwide distributions of these mosquito species overlap. Shared larval habitats and shifts in the distribution and abundance of resident A. albopictus or A. aegypti after the establishment of the other species suggest that competitive displacement occurs. Experiments on larval competition between North American populations of the two species showed that A. albopictus has the competitive advantage under local field conditions, which apparently accounts for displacement of A. aegypti from much of the United States after the invasion of A. albopictus. The role of competition, and potential shifts of competitive advantage in different parts of their worldwide ranges are unknown, but variation due to intraspecific or environmental differences is possible. In the current study, we measured the performance of larvae of Brazilian populations of A. albopictus and A. aegypti competing under field conditions in Rio de Janeiro, Brazil. Finite rates of increase for each species were estimated and the effects of species composition, larval density, and leaf litter resource levels were determined. A. albopictus maintained positive population growth at higher combined densities and lower per capita resource availability than did A. aegypti. A. albopictus showed higher survivorship than A. aegypti under all treatments and leaf litter resource levels. These results indicate that in Brazil, just as in North America, A. albopictus is a superior larval competitor to A. aegypti when exploiting leaf litter resources. Our results further suggest that this competitive advantage for A. albopictus is likely to be independent of mosquito population origin, local environmental conditions, and local differences in the types of leaves that form the resource base of the aquatic habitats of larvae. [ABSTRACT FROM AUTHOR]

Summary In an olfactometer study on the response of the anthropophilic malaria mosquito Anopheles gambiae s.s. (Diptera, Culicidae) to human sweat it was found that freshly collected sweat, mostly of eccrine origin, was attractive, but that incubated sweat was significantly more attractive than fresh sweat. The behavioural response to l-lactic acid and ammonia, the main constituents of sweat, was investigated. l-lactic acid was attractive at one concentration only (11.11 mm) and removal of the l-lactic acid from the sweat by enzymatic decomposition did not affect the attractiveness of sweat. Ammonia caused attraction over a range of 0.1–13.4 m on glass slides and at 0.84–8.40 μmol/min in an air stream. It is concluded that: human sweat contains kairomones for host-seeking An. gambiae; ammonia is an important kairomone for this mosquito; and that l-lactic acid is not a prerequisite in the attraction of An. gambiae to sweat. [ABSTRACT FROM AUTHOR]

SummaryFor collecting mosquitoes (Diptera: Culicidae) the outdoor catching efficiency of four types of trapping devices baited with carbon dioxide (CO2, 300 ml/min) was evaluated and compared in two areas of Tanzania. The types of traps employed were: the CDC miniature trap with the incandescent light bulb switched on or off; electric nets (ENT) and a Counterflow Geometry (CFG) trap. In Njage, south-east Tanzania, Anopheles gambiae Giles sensu stricto was the most abundant of the seven mosquito species obtained, comprising of 74.3% of the total number caught (n = 2171). In Muheza, north-east Tanzania, Culex quinquefasciatus Say was the predominant species (90.9%) among 1080 caught. At both localities the CFG trap was superior to the CDC trap with light-on or light-off for sampling both An. gambiae and Cx. quinquefasciatus. Efficiency of the CFG trap and ENT were similar for sampling these species of mosquitoes (P > 0.05). However, ENT was superior to the CDC trap with light-off for collecting both species. Significantly more (P < 0.05) Cx. quinquefasciatus were obtained by the CDC trap with light-off than with light-on, especially outdoors. It is concluded that both ENT and the CFG are effective tools for sampling populations of An. gambiae and Cx. quinquefasciatus outdoors. [ABSTRACT FROM AUTHOR]

The article discusses a study on the presence of Culex pipiens biotype molestus in the Netherlands and of the hybrid biotype pipiens and molestus in Northern Europe. Culex pipiens complex members are cited as the principal vectors for the transmission of the West Nile virus (WNV) in North America and Europe. It compares the biotypes pipiens and molestus, the first of which is said to be seasonally active while the latter is active throughout the year. Results of the study indicate that both biotypes exist in the region where research is focused.

Objectives: In the context of public health, risk governance (or risk analysis) is a framework for the assessment and subsequent management and/or control of the danger posed by an identified disease threat. Generic frameworks in which to carry out risk assessment have been developed by various agencies. These include monitoring, data collection, statistical analysis and dissemination. Due to the inherent complexity of disease systems, however, the generic approach must be modified for individual, disease-specific risk assessment frameworks. Study design: The analysis was based on the review of the current risk assessments of vector-borne diseases adopted by the main Public Health organisations (OIE, WHO, ECDC, FAO, CDC etc...). Methods: Literature, legislation and statistical assessment of the risk analysis frameworks. Results: This review outlines the need for the development of a general public health risk assessment method for vector-borne diseases, in order to guarantee that sufficient information is gathered to apply robust models of risk assessment. Stochastic (especially spatial) methods, often in Bayesian frameworks are now gaining prominence in standard risk assessment procedures because of their ability to assess accurately model uncertainties. Conclusions: Risk assessment needs to be addressed quantitatively wherever possible, and submitted with its quality assessment in order to enable successful public health measures to be adopted. In terms of current practice, often a series of different models and analyses are applied to the same problem, with results and outcomes that are difficult to compare because of the unknown model and data uncertainties. Therefore, the risk assessment areas in need of further research are identified in this article. [ABSTRACT FROM AUTHOR]