Spatio-Temporal Analysis of Reinfestation by Triatoma Infestans (Hemiptera: Reduviidae) Following Insecticide Spraying in a Rural Community in Northwestern Argentina

Abstract

The spatio-temporal reinfestation patterns by Triatoma infestans following a blanket insecticide spraying in the rural community of Amama in northwestern Argentina were analyzed using a geographic information system, satellite imagery, and spatial statistics. Domestic and peridomestic reinfestation by triatomine bugs was monitored from 1993 to 1997. Triatoma infestans was detected at least once in 75% of 2,110 sites evaluated. The prevalence of sites positive at least once for T. infestans during the study period increased sharply from 1993-1995 (0.6-2.9%) to November 1997 (32%). The initial source of T. infestans was a pig corral in southern Amama one year post-spraying. Subsequent infestations were clustered around this initial focus at a distance of approximately 400 meters starting in 1995. In 1996, clustering was maximized in sites within the same or in neighboring compounds at distances of 25-175 meters. An effective control program on the community level will be based on the spraying of actual epicenters and sites within 450 meters of these epicenters to prevent the propagation of T. infestans.

Dispersal of Triatoma infestans and other Triatominae species in the arid Chaco of Argentina: Flying, walking or passive carriage? The importance of walking females

“…Active flight dispersion -It has been suggested that low W/L (< 8 mg/mm) is the trigger for flight dispersal in adult T. infestans (Schofield 1980, Carcavallo 1985, especially in individuals from the peridomicile (Cecere et al 2004), which are considered the main reinfestation sources of human dwellings. In this study, the average W/L of flying T. infestans was 8 mg/mm (starved) in both sexes, supporting the hypothesis that the need for food is an important factor in flight initiation (Lehane & Schofield 1982.…”

“…These areas present complex structures that not only prevent good penetration of insecticide but also expose the chemical to climatic factors that accelerate its degradation (Schofield 1994). The persistence of vector populations instead in these habitats has led to proposals that the peridomicile, from which the insects disperse by flight, is the origin and principal source of reinfestation of houses after an insecticide application (Schofield 1980, Carcavallo 1985, Cecere et al 2004.…”

Identification and characterization of microsatellite markers in the Chagas disease vector Triatoma infestans (Heteroptera: Reduviidae)

“…The peridomicile, where most failures in control and detection may occur, is usually the first area to be recolonized and contains the greatest abundance of T. infestans 1 year post-spraying (Cecere et al, 2002). Moreover, as discussed by Cecere et al (2004), a single peridomestic structure hosting a residual focus could be the origin of reinfestation by flight-dispersing bugs to sites located within a 450 m radius. However, there is no definitive evidence to support this hypothesis.…”

A Paratransgenic Strategy for the Control of Chagas Disease

“…However, sustainability of this program has been called into question due to the need for continued application of pyrethroid insecticides and possibility of reinfestation of domestic structures [19]. The poor effects of pyrethroid insecticides are mainly caused by their shortlasting residual effects in outdoor sites exposed to sunlight, high temperatures, rain, and dust [20,21]. The reduced effectiveness of pyrethroids was further compounded by the development of triatomine populations that were resistant to a variety of insecticides in Chagas disease endemic areas [22].…”