The influence of temperature on the biology of Biomphalaria glabrata (Say), intermediate host of Schistosoma mansoni on St. Lucia, West Indies

Life tables were obtained over 16 fortnights for three cohorts of Biomphalaria glabrata at 20§C, 25§C and 30§C respectively. At 35§C no eggs hatched. The intrinsic rate of natural increase r was greater at 25§C(0.8834) but the mean generation time T was similar to that at 30§C(8-9 fortnights). Egg production and survival were reduced at 30§C but r(0.6866) was higher than at 20§C(0.4725). T was greatest at 20§C(12 fortnights) due to the delay in the onset of egg laying. The growth rate at 30§C was only a little faster than that at 25§C, but both were greater than that at 20§C. Comparison of these results with those of similar studies elsewhere suggests that the St. Lucians strain of B. glabrata is adapted to living in unstable, temporary habitats. B. glabrata, unlike its African relatives, is capable of surviving prolonged exposure to temperatures of 30§C so that, despite reduced fecundity, it can colonize the hot, low lying coastal plains of northeastern South America. (AU)

Arbovirus studies in Bush Bush Forest, Trinidad, W.I., September 1959-December 1964. III. Entomologic studies

Bush Bush Forest entomologic investigations were concered mainly with mosquitoes, the most conspicuous element of the bloodsucking arthropod fauna. More than 92 species were demonstrated, but only about two dozen were common. Mosquitoes were studied in relation to thier physical environment, seasonal activity, diel activity, horizontal stratifaction in the forest, food preferences, and larval habitats. Large numbers were collected for virus studies. Other groups investigated were phlebotomine flies (10 species), Culicoides flies (10 species), horseflies (18 species), Cuterebridae (one species), sucking lice (four species), fleas (one species), ticks (nine species), and various mites including 15 species of trombiculid. (AU)