Chagas' Disease in the Amazon Basin: III. Ecotopes of ten triatomine bug species (Hemiptera: Reduviidae) from the vicinity of Belem, Pará State, Brazil

Abstract

Tracking mammals to their nests or refuges, microhabitat dissection, light traps and surveillance of human dwellings were employed to identify sylvatic triatomine species and their natural ecotopes in the vicinity of Belém, Pará State, Brazil. Ten species were found: Rhodnius pictipes, R. robustus, R. paraensis, Panstrongylus lignarius, P. geniculatus, P. rufotuberculatus, Eratyrus timeronatus, Microtriatoma trinidadensis, Belminus herreri and Triatoma rubrofasciata. All species except P. rufotuberculatus (only 1 specimen examined), B. herreri and T. rurofasciata were infected with Trypanosoma cruzi; Triatoma rubrofasciata was infected with Trypanosoma conorrhini. Natural ecotopes were defined principally in terms of specific habitats, such as burrows and hollow logs (P. geniculatus), palm crowns (R. pictipes, R. robustus), large hollow trees (E. mucronatus, P. lignarius nymphs), small arboreal cavities (P. lignarius, R. paraensis), folded leaves within nests (M. trinidadensis), beneath loose tree bark (B. herreri), and inside buildings (T. rubrofasciata). Only species showed signs of obligate dependence on particular hosts. E. mucronatus was extraordinary in that nymphs fed on invertebrates in nature, as well as on the porcupine Coendou prehensilis. All species except P. geniculatus and M. trinidadensis could be maintained experimentally. R. pictipes and T. rubrofasciata commonly invaded houses, while P. geniculatus and P. lignarius occasionally did so. R. pictipes bugs entering houses were usually heavily infected with T. cruzi. Light-attracted sylvatic R. pictipes, originating from heavily infested mucajá palms (Acrocomia sclerocarpa), were considered the primary source locally sporadic and acute suburban cases of Chagas' disease. The incursion of domestic vectors into the Amazon basin from known endemic areas is considered to threaten the region with endemic Chagas' disease. Specific suggestions are given for measures to prevent both new sporadic cases of sylvatic origin and emergent endemic foci.