Patterns ofAedes aegypti(Diptera: Culicidae) Infestation and Container Productivity Measured Using Pupal andStegomyiaIndices in Northern Argentina

Abstract

A citywide control program of Aedes aegypti (L.) (Diptera: Culicidae) mainly based on the use of larvicides reduced infestations but failed to achieve the desired target levels in Clorinda, northeastern Argentina, over 5 yr of interventions. To understand the underlying causes of persistent infestations and to develop new control tactics adapted to the local context, we conducted two pupal surveys in a large neighborhood with ≈2,500 houses and recorded several variables for every container inspected in fall and spring 2007. In total, 4,076 lots and 4,267 containers were inspected over both surveys, and 8,391 Ae. aegypti pupae were collected. Large tanks used for potable water storage were the most abundant and the most productive type of container, accounting for 65–84% of all the pupae collected. Therefore, large tanks were key containers and candidates for improved targeted interventions. Multivariate analysis showed that containers located in the yard, at low sun exposure, unlidded, filled with rain water, and holding polluted water were all more likely to be infested by larvae or pupae. When only infested containers were considered, productivity of pupae was most closely associated with large tanks and rain water. A stochastic simulation model was developed to calculate the expected correlations between pupal and Stegomyia indices according to the characteristics of the distribution of larvae and pupae per container and the spatial scale at which the indices were computed. The correlation between pupal and Stegomyia indices is expected to increase as infestation levels decline.

Productive Container Types for Aedes aegypti Immatures in Mérida, México

“…aegypti immatures is that they can differ dramatically between local areas. This has been demonstrated in a series of multicountry studies (Focks and Alexander 2006, Tun-Lin et al 2009, Arunachalam et al 2010 and also is evident when comparing the results of studies focusing on individual geographical areas (Moore et al 1978;Winch et al 1992;Kittayapong and Strickman 1993;Focks and Chadee 1997;Danis-Lozano et al 2002;Pinheiro and Tadei 2002;Arredondo-Jimenez and Valdez-Delgado 2006;Barrera et al 2006Barrera et al , 2008Bisset et al 2006;Lenhart et al 2006;Midega et al 2006;Morrison et al 2004Morrison et al , 2006Romero-Vivas et al 2006;Chadee et al 2007Chadee et al , 2009Hammond et al 2007;Koenraadt et al 2007;Maciel-de-Freitas et al 2007; Barbazan et al 2008;Manrique-Saide et al 2008;Troyo et al 2008;David et al 2009;Garelli et al 2009;Lambdin et al 2009;Tsuzuki et al 2009;Kamgang et al 2010). Furthermore, the most productive container types can change over the year, especially in settings with dry and wet seasons where the importance of containers Þlled by rain, relative to those Þlled by human action, may vary over the year in response to the seasonal rainfall patterns (Pinheiro and Tadei 2002, Lenhart et al 2006, RomeroVivas et al 2006, Maciel-de-Freitas et al 2007…”

Water Use Practices Limit the Effectiveness of a Temephos-Based Aedes aegypti Larval Control Program in Northern Argentina

“…The program successfully limited dengue transmission and significantly reduced larval indices but failed to maintain them below target levels (the city-wide Breteau index was rarely <5%). Large tanks were found to be the most productive type of water-holding container [7], as in several studies around the globe [8]–[11]. Significant larval resistance to temephos was not recorded locally [12].…”

Diversity of containers and buildings infested with Aedes aegypti in Puerto Iguazú, Argentina

“…urban studies 4,5,9,10 . In two cities in Argentina, entomological indices were higher than in Puerto Iguazú (HI: 67-76%; CI: 18-39%; BI: 127-249) 9,10 .…”

“…aegypti is able to lay eggs in a diverse range of objects containing clean water, some types of artificial containers were described as more relevant, due to their availability and large number. Large containers have been especially identified as the most important container type because of their large production capacity 4 .…”