Population dynamics of Triatoma infestans under natural climatic conditions in the Argentine Chaco

Abstract

Using experimental chicken houses at a site in central Argentina where the bug Triatoma infestans (Klug) is endemic, nine populations of this vector of Chagas disease were monitored during a 34-month period. Bug populations with four chickens as hosts were consistently larger than those with two chickens as hosts. Age structure of the bug population followed a similar pattern irrespective of the initial age structure. Egg to adult mortality was consistently around 98.5% and there was no consistent evidence for density-dependent mortality. There was some evidence for density dependence in fecundity and recruitment rates, but these were heavily constrained by low temperatures during the winter months. Nymphal development rates correlated most strongly with mean minimum temperatures rather than with mean maximum temperatures. We conclude that vector control using insecticides against this species would be most effective at the onset of winter, when recovery of any surviving populations would be inhibited by low temperatures.

Wild Triatoma infestans, a potential threat that needs to be monitored

“…The stage-structure pattern of the dark morph population is still unknown. Although domestic T. infestans produce two generations a year in the warm climate of the Chaco (Gorla & Schofield 1989), fluctuations in host availability in wild habitats might put the dark morph at a disadvantage and lead to an increased development time.…”

Interacción entre poblaciones de Triatoma infestans y Triatoma sordida

“…de profundidad, ( Fig. 1 y 2) respondiendo a la estructura básica usada por Gorla y Schofield 6 . El recurso alimentario utilizado consistió en un ave (gallina).…”

“…La fecundidad mensual fue obtenida como la razón entre el total de huevos (embrionados, eclosionados y muertos) y el número de hembras vivas marcadas más el 0,25 de las hembras vivas sin marcar, al tiempo t 7 .…”

“…Las tasas de fecundidad de T. infestans y T. sordida no se corresponden con el mayor reclutamiento de hembras. La correlación negativa entre el número de hembras y el promedio de huevos por hembra coincide con lo constatado por Gorla y Schofield 7 .…”

“…La renovación ninfal de las especies en estudio, no mostró relación estrecha con la temperatura y humedad relativa de cría, a diferencia de lo comprobado para T. infestans, por Gorla y Schofield 7 .…”