Unusual productivity of Aedes aegypti in septic tanks and its implications for dengue control

Abstract

Increased DEN-2 virus transmission in Puerto Rico during 2005 prompted the implementation of a rapid intervention programme to suppress Aedes aegypti (L.) (Diptera: Culicidae) emergence, which in turn lead to the discovery of previously unknown breeding sites underground. Initially, the following control measures were applied in Playa/Playita (PP), a town of 1,400 households, to all areas where the number of pupae per person exceeded the expected threshold for dengue transmission; all containers likely to be aquatic habitats were turned over and containers too large to turn were treated with 1 p.p.m. methoprene. The impact of these interventions was evaluated by comparing the number of resting adult mosquitoes (by backpack aspiration and sweepnetting in bedrooms) pre-intervention, with numbers at 3 and 5 weeks post-intervention, and by evaluating pupal density at 4 weeks post-intervention in PP and in a nearby town, Coqui (CO; 1500 households), which was not treated. The pre-intervention and post-intervention densities of resting Ae. aegypti adults were significantly larger in the intervention town, although the density of pupae in surface containers was low and similar in both towns at 4 weeks post-intervention. At 3 weeks post-intervention, the density of resting adults decreased by only 18% of pre-intervention levels, but returned to pre-intervention levels 5 weeks after treatment. By contrast, the density of resting adults in CO steadily decreased to 48% and 61%, at 3 and 5 weeks after the initial surveys, respectively. Geographical Information Systems identified significant clustering of adult mosquitoes, which led to the discovery of underground aquatic habitats (septic tanks) that were producing large numbers of Ae. aegypti and Culex quinquefasciatus (Say) in the treated town. We calculated that septic tanks could produce > 18 000 Ae. aegypti and approximately 170 000 Cx quinquefasciatus adults per day. Septic tanks are likely to be common and widespread in suburban and rural Puerto Rico, where, apparently, they can contribute significantly to the maintenance of island-wide dengue virus endemicity.

Mosquito Infestation and Dengue Virus Infection in Aedes aegypti Females in Schools in Mérida, México

“…Together with previous studies from home environments showing a preference of Ae. aegypti females for bedrooms, 7,[58][59][60][61] this underscores the importance of a detailed understanding of indoor-use patterns by key mosquito vector species in different indoor environments to most effectively implement indoor-targeted control measures.…”

Comparative account of energy reserves in four co-occurring mosquito species in Kolkata, India (Diptera: Culicidae)

“…However, variations in the pupal weight was not considerably high as known for the four mosquito species considered (ADITYA & SAHA 2013, BANERJEE et al 2013a, 2013b, 2015, thereby leaving a chance of error to generalize the observations of the present study. Energy reserves show a considerable positive correlation with the pupal weight, but may be controlled with the developmental requirements of somatic and reproductive tissues (JULIANO et al 2004, MURRELL & JULIANO 2008, ARRIVILLAGA & BARRERA 2004, BARRERA et al 2008. Thus the variations in energy reserves observed in the four co-occurring mosquitoes are a reflection of the differences in their life history strategies and adaptations to environmental conditions.…”

Insecticide Susceptibility of Aedes aegypti L. (Diptera: Culicidae) in Guerrero, Mexico

“…87 Los contenedores para conservar el agua y los bebederos para animales deben limpiarse (fregando y enjuagando) y protegerse con cubiertas ajustadas. Algunos contenedores, como utensilios (bandejas para pintura, cubetas) y botellas, deben guardarse de tal forma que se evite la acumulación de agua (por ej., en posición invertida, debajo de un techo).…”