The Ecology and Natural History of Wild Triatominae in the Americas

Abstract

Triatomine bugs, the vectors of Chagas disease, feed primarily on vertebrate blood and live in close association with their hosts. Here we provide an updated synthesis of current knowledge about the ecology and natural history of the 140+ American triatomine-bug species. We suggest that the bugs’ highly diverse lifestyles fall into two major classes. “Sit-and-wait” nest specialists are associated with the nests of particular hosts – on which the bugs feed almost ectoparasitically. Active-foraging, “stalker” host generalists, in contrast, occupy certain discrete microhabitats (rock outcrops, trees, palm crowns, etc.) and feed opportunistically on the potentially diverse vertebrates that also use those microhabitats. Within each foraging-lifestyle class, triatomines have adapted to widely diverse ecoregions, from deserts to rainforests, and habitats, from underground to forest canopy. About half of all living species are arboreal and about half are terrestrial. All likely descend, however, from a tree-dwelling, host-generalist “stalker” ancestor; the “sit-and-wait,” nest-specialized lifestyle independently evolved several times to yield ~30% of extant taxa. Foraging-related adaptations may have contributed significantly to shaping the morphological, physiological, and behavioral diversity of the bugs. From a practical standpoint, we note that the most dangerous domestic vectors of Trypanosoma cruzi (Triatoma infestans, Rhodnius prolixus, and Triatoma dimidiata) are opportunistic “stalkers” – i.e., bugs that were preadapted to feed on diverse hosts in shared microhabitats. We expect that, by introducing a fresh perspective on triatomine-bug ecology and behavior, our “foraging-lifestyle hypothesis” will open new research avenues and will thus, ultimately, contribute to the development of improved strategies for the prevention of vector-borne Chagas disease.