TRIATOMA-INFESTANS IS MORE EFFICIENT THAN PANSTRONGYLUS-MEGISTUS IN OBTAINING BLOOD MEALS ON NONANESTHETIZED MICE

We compared the influence of bug density in the capacity of Triatoma i nfestans and Panstrongylus megistus in obtaining blood meal in non ana esthetized mice. The regression analysis for increase in body weight ( mg) versus density (no. of bugs/mouse) showed that in experiments with anaesthetized mice (RIM), no correlation was observed In experiments with non anaesthetized mice (NAM) the weight increase was inversely pr oportional to density. The regression slope for blood meal size on den sity was less steep for T. infestans than for P. megistus (-1.9 and -3 .0, respectively). The average weight increase of P. megistus nymphs i n experiments with AM was higher than for T infestans nymphs; however in experiments with NAM such results were inverted Mortality of P. meg istus was significantly higher than that of T. infestans with NAM. How ever in experiments with AM very low mortality was observed Considerin g the mortality and the slope of regression line on NAM, T. infestans is more efficient than P. megistus in obtaining blood meal in similar densities, possibly because it caused less irritation of the mice. The better exploitation of blood source of T. infestans when compared wit h P. megistus in similar densities, favours the maintenance of a bette r nutritional status in higher densities This could explain epidemiolo gical findings in which T infestans not only succeeds in establishing larger colonies but also dislodges P. megistus in human dwellings when it is introduced in areas where the latter species prevails.