Parasite/host-interrelationships of the trypanosomatids Trypanosoma cruzi and Blastocrithidia triatomae and the reduviid bug Triatoma infestans: influence of starvation of the bug.

We have investigated the effects of Trypanosoma cruzi and Blastocrithidia triatomae on the life span of starved second/third (L2/3), third/fourth (L3/4), and fourth/fifth instars (L4/5) of Triatoma infestans, which had been infected in the first instar and fed last in the second, third or fourth instar respectively. The intestines and sometimes also the flagellate populations of dead bugs were examined. In uninfected L2/3 a higher relative humidity prolonged the life span. With a maximal survival of 14 months, uninfected L3/4 were the most resistant to starvation, followed by L4/5 and then L2/3. Trypanosoma cruzi reduced the life span of starved L3/4 and L4/5 by only 14% and 17%, respectively. Infection with B. triatomae reduced life spans by 51% (L2/3), 55% (L3/4) and 32% (L4/5). The intestines of dead infected bugs were more likely to contain incompletely-digested blood remnants than those of uninfected bugs; living flagellates occurred in all parts of the intestine, and often the rectal lumen contained more dead flagellates than were found on the rectal wall.