ABSTRACT
Several species of snails, including Pomacea haustrum, Marisa cornuarietis and Helisoma duryi, have been identified as probable competitors and/or predators of planorbid intermediate hosts of Schistosoma. During the last few years, studies carried out in the Caribbean region have shown reductions and even disappearances of populations of Biomphalaria glabrata and B. straminea in breeding places where the snail Melanoides tuberculata was introduced. Observations made over a period of 10 years in two lakes close to Belo Horizonte, MG, showed that there were marked reductions in autochthonous populations of B. glabrata and B. straminea after the arrival of M. tuberculata, both Biomphalaria species disappearing completely after eight years
Subject(s)
Animals , Competitive Behavior/physiology , Snails/physiology , Biomphalaria/physiology , Brazil , Population Density , Predatory BehaviorABSTRACT
Published and unpublished observations on geographical distribution of Biomphalaria snails in the State of Minas Gerais, Brazil, were compiled. This work is aimed at knowing the present occurrence of Biomphalaria species in this region, and at contributing to the elaboration of the planorbid chart of Minas Gerais. In malacological surveys, performed by several researchers, the presence of seven species of this genus was recorded. Those planorbids were found in 12 mesoregions, in 283 (33.1 percent) municipalities out of 853 with the following distribution: B. glabrata (185 municipalities), B. straminea (125), B. tenagophila (58), B. peregrina (57), B. schrammi (26), B. intermedia (20) and B. occidentalis (2). B. glabrata and B. tenagophila are found naturally infected by Schistosoma mansoni in Minas Gerais. In 24 municipalities the three snail hosts of S. mansoni in Brazil, B. glabrata, B. tenagophila and B. straminea, are present
Subject(s)
Animals , Biomphalaria/classification , Demography , Disease Vectors/classification , BrazilABSTRACT
Existem atualmente na regiäo metropolitana de Belo Horizonte 18 parques urbanos (também denominados "parques ecológicos") com coleçöes hídricas (lagoas, nascentes, córregos etc). Pesquisas iniciais em 17 destes parques mostraram a ocorrência de moluscos hospedeiros intermediários do Schistosoma mansoni em pelo menos quatro deles. Capturas mensais nestes parques, de agosto/94 a fevereiro/96, mostraram os seguintes resultados em relaçäo aos planorbíneos: Parque Julien Rien: 1.145 exemplares de Biomphalaria glabrata (2 mm a 13 mm); Parque Betânia: 149 exemplares de B. glabrata (4 mm a 13 mm); Parque Santa Lúcia: 2.431 exemplares de B. straminea (3 mm a 9 mm) e Parque Lagoa do Nado: três exemplares de B. tenagophila (3 mm a 10 mm). As visitas aos parques teräo prosseguimento e, após um diagnóstico sobre a situaçäo de cada parque, seräo sugeridas às autoridades municipais medidas de controle e/ou erradicaçäo adequadas a cada área.
Subject(s)
Animals , Biomphalaria , Parks, Recreational , Coastal Lagoon , MolluscaABSTRACT
A population of Biomphalaria occidentalis was found for the first time in the State of Minas Gerais. It was probavly introduced into the Várzea das Flores dam, in the municipality of Contagem, the area o0f study, during fish stocking in 1985. There is possibility of "competitive exclusion"between that species and B. glabrata, previously the only Biomphalaria found in the region. The present geographical distribution of B. occidentalis in Brazil is listed.