Ecology and Control of Triatomine (Hemiptera: Reduviidae) Vectors of Chagas Disease in Guatemala, Central America

Abstract: This thesis analyses several factors affecting the control of triatomines in Guatemala. There are three synantropic triatomines in Guatemala, i.e., Rhodnius prolixus, Triatoma dimidiata and T. nitida. Their distibution is mainly at an altitude between 800 and 1500 m a.s.l. R. prolixus and T. nitida have localized but scaterred distibution while T. dimidiata is present in 21 of the 22 departments in the country. Several investigations have shown that R. prolixus could be relatively easily eradicated while T. dimidiata may be more difficult to control, since it is present in domestic, peridomestic and sylvatic environments showing high diversity and a variety of epidemiological characteristics. Based on the incidence of Trypanosma cruzi infection in humans in the distributional areas of the triatomines, R. prolixus appear to be a more competent vector than T. dimidiata. This is despite the fact that these vectors have similar infection rates. Inside houses, R. prolixus and T. dimidiata and in artificial environments, T. ryckmani and T. dimidiata, preferred the northern side of the walls. Therefore, selective application of insecticides should focus on walls and furniture located in the northern part of the house. House improvements reduced the infestation of triatomines, and could be used as a complement to insecticidal spraying. Although T. dimidiata is not an efficient vector its wide distribution, versatility in occupying different habitats and capacity to disperse render this species difficult to control in Central America. Thus, only few months after insecticidal spraying T. dimidiata had reinfested the domestic environments. Morphometic methodology and genetic markers have been developed to differentiate within-species populations of T. dimidiata and T. nitida. Studies on the migration patterns of sylvatic T. dimidiata and T. ryckmani have been performed in order to clarify the colonization patterns. The adults migrate, in particular, in the dry part of the year. This finding may be of help in attempts to control T. dimidiata.