Marcacao de Panstrongylus megistus (Hemiptera, Triatominae) com radioisotopos. / Labelling of Panstrongylus megitus (Hemiptera, Triatominae) with radioisotopes

Desenvolveram-se experimentos no campo e em laboratorios com Panstrongylus megistus marcados com pequenos fios de Ir-192 colados ao pronoto. Barbeiros silvestres assim marcados e liberados, foram posteriormente detectados em galinheiros com auxilio de contador Geiger-Muller e de caixas de Gomez-Nunez. Verificou-se que alguns exemplares marcados foram encontrados 12 dias depois, a 150 m de distancia do ponto de liberacao, circulando entre ambientes silvestres e domiciliares. E possivel que um dos estimulos para o barbeiro localizar um novo habitat seja a presenca de feromonio em domicilios ja infestados

[Observations upon some factors which influence the laboratory maintenance of Schistosoma mansoni (author's transl)]. / Observações sobre alguns fatores que influem na manutenção do Schistosoma mansoni em laboratório.

Schistosoma mansoni has been maintained in the laboratory using a laboratory strain of B. glabrata, white mice (Mus musculus) and golden hamster (Cricetus auratus). Observations were collected during five consecutive years and the results were analysed for factors which might have influenced them. The analysis has shown that--(1) snail mortalities were independent of the relatively small variation in temperature and of the mean number of miracidia used for infection; (2) rate of infection of snails increased slowly with the increase of the mean number of miracidia; (3) the temperature was in reciprocal proportion with the logarithm of the cercarial development period; (4) the yield of viable eggs has increased steadily in white mice during the observation period; (5) significant increase of egg production was observed in golden hamsters when subcutaneous route of inoculation was used instead of inoculation through the alimentary pouch.

[Influence of EDTA on growth and reproduction of Biomphalaria glabrata (author's transl)]. / Influência do EDTA sobre crescimento e reprodução de Biomphalaria glabrata.

The influence of EDTA on B. glabrata has been investigated. Newly hatched snails were exposed to concentrations of EDTA from 1 to 64 ppm, and young (diameter of 6 mm) snails to concentrations of 50, 80 and 100 ppm, for periods of 90 days. Fifty percent reduction of egg productivity has been caused by concentration of 16 ppm of EDTA while 50% of mortality has occurred at about 70 ppm. The calcium and iron content both in treated and non-treated young snails have been estimated by atomic absorption photometry. The uptake of calcium was 40, 83 and 90% less for calcium and 37, 77 and 81% less for iron as compared with the untreated group. The calcium content of the shell was 5--15 times greater than that of the soft body, while the iron content of those two parts was in the proportion of 1:1. These proportions were maintained constant in the treated and non-treated groups. The interference of increasing concentrations of EDTA has resulted in the proportional reduction of growth-rate, reproduction rate and of longevity of the exposed snails.

Laboratory observations on the biological control of Biomphalaria glabrata by a species of Pomacea (Ampullariidae).

Laboratory experiments have shown that medium-sized (30-50 mm in shell height) Pomacea sp. snails consumed the egg masses of Biomphalaria glabrata deposited either on glass or on the leaves of Salvinia, and that they also caused a high mortality rate among the newly hatched B. glabrata. When the two species of snail were kept in the same tank, the Pomacea sp. caused a reduction in the B. glabrata egg density in proportion to their relative numbers and the presence of Pomacea sp. prevented colonies of B. glabrata from becoming established. The identity of the Pomacea sp. has not yet been satisfactorily established.