Two triatomine genera (
Panstrongylus
and
Triatoma
) have essentially been recorded in Rio Grande do Sul State, Brazil.
Panstrongylus megistus
should be highlighted since this species is one of the main vectors of
Trypanosoma cruzi
in Brazil, due to its wide geographical distribution and the high susceptibility to this protozoan. This study aimed to present not only the occurrence and distribution of
P. megistus
in the Porto Alegre city’s metropolitan area (PAMA), Rio Grande do Sul State, Brazil, but also the rates of
T. cruzi
infection, from 2009 to 2020. The PAMA, which comprises 34 cities and 4.4 million habitants, extends across the transition area in two biomes – Pampa and Mata Atlantica – found in the state. Results showed that
P. megistus
was recorded in 76.5% of cities (i.e., 26 out of 34), mainly in Porto Alegre city, where the vector was found in 11 out of the 12 years that were monitored. Three hundred and nineteen specimens were captured. Two hundred and sixty-seven specimens (83.7%) were located intradomicile (p < 0.0001), while 52.3% positivity for
T. cruzi
was found. Thus,
P. megistus
is important in the PAMA, because it invades and colonizes the households. Moreover, the high rates of
T. cruzi
infection have drawn attention.