Potential for domestication of Panstrongylus geniculatus (Latreille, 1811) (Liemiptera, reduviidae, triatominae) in the municipality of Muaná, Marajó island, state of Pará, Brazil.

Abstract

Panstrongylus genicutalus is a triatomine bugassociated in the classical manner with animal bur-rows in humid forests, especially with armadillosthat are the principal reservoirs of Z3 of Trypano-soma cruzi (Lent & Wygodzinski 1979, Sherlock1979, Miles et al. 1981). In spite of its occasionalentry into houses where it is attracted by light, thistriatomine has not established itself in habitations,an important factor in limiting the potential of thisspecies as a vector of Chagas disease to man (Naiffet. al 1998). Colonization by this species of pig-sties near to and contiguous with human dwell-ings in the Amazon River floodplain is here re-ported, for the northern Brazilian municipality ofMuana on Marajo Island in the Amazon River es-tuary, with concomitant invasion of human domi-ciles and attacks on residents therein (Valente etal. 1998).During field work, 564 triatomines were col-lected in houses, outbuildings and palm trees atthe localities Pau Grande, Capitariquara, Inamaru,Mocajatuba, Abacatal River, and Flexal. Five spe-cies were found: P. genicutatus, Rhodnius pictipes,P. lignarius, R. robustus, and Eratyrus mucronatus,with the first mentioned species being dominant(89.4%). This species showed an index of 16.4%(27/167 specimens examined) in natural infectionby trypanosome type cruzi.Only Z1 of T. cruzi, previously associated withmarsupials and R. pictipes, was isolated fromtriatomines and mammals in the vicinity. The natu-ral infection by P. geniculatus by Z1 suggests achange in the behavior of this vector, most likelydue to alterations in its environment (Valente et.al. 1998). In all, 26 specimens of this species oftriatomine were collected in human dwellings, 5(18.5%) naturally infected with the trypanosome.Of 122 houses examined, 28 (23%) were in-fested and yielded a total of 40 adult triatomines.Some 114 domestic mammals (105 pigs, 5 dogs,and 4 cats) and 7 wild mammals (4 Didelphismarsupialis, 2 Philander opossum, and 1Proechymis guyanensis) were examined, and natu-ral trypanosome infections were found in 4 pigs(Sus scrofa) (2.8%), 4 D. marsupialis and 1 P. opos-sum. The natural infection of domestic pigs withZ1 in sties colonized by P. geniculalus is a relevantfinding, as well as being the first report of an asso-ciation between triatomines and domestic animalsin the Amazon Basin (Valente 1998).No human trypanosome infection was found inthe studied communities, where 582 residents of atotal population of 678 people were tested, and allwere serologically negative. The possibility of in-fections arising from the proximity to swine ispresent, especially given the local, exuberant habitof some people of smearing their unprotected handswith pig blood during butchering of the animals.The registered adaptability of P. geniculalus toswine and pigsties in the vicinity of human dwell-ings, in the floodplain, and their attack on peoplein houses, indicate that this could be a potentialpathway to the domestication of this triatomine inthe Amazon River delta (Valente 1998).From this study the following conclusions canbe made: (1) colonization by P. gerncuialus of pig-sties near human habitations has been demon-strated, and specimens of this species naturally in-fected with Z1 of T. cruzi were collected in theadjoining human dwellings where there was alsosome evidence that these triatomines may havebitten people, in spite of these findings, no humaninfection of T. cruzi was found in the study com-munity; (2) five species of triatomines are foundin the study area: P. geniculatus, R. pictipes, P.