THE DEVELOPMENT OF TRYPANOSOMA-CRUZI (TRYPANOSOMATIDAE) IN THE REDUVIID BUG TRIATOMA-INFESTANS (INSECTA) - INFLUENCE OF STARVATION

Fifth instars of Triatoma infestans with established Trypanosoma cruzi infections were dissected after different periods of starvation to de termine the population density and the percentage of different develop mental stages of T. cruzi in the small intestine and rectum of the bug s. After a short starvation period of 20 days, the population density in the small intestine was 20% (about 60,000) of the rectal population . The population in the small intestine was strongly reduced after an additional ten days of starvation, and no flagellates could be found t here 60, 90 and 120 days after the last feeding. In the rectum, this r eduction went down to 1% of the initial population, but a total elimin ation never occurred. Usually the remaining population contained more live than dead flagellates. Starvation also resulted in an increase in the rectum in the number and percentage of drop-like forms, intermedi ates between sphere-and epi-or trypomastigotes, from 1% initially to a bout 10% after 90 days of starvation. The percentage of spheromastigot es increased from 2% at 20 days after the last feeding to about 20% af ter an additional 40 and 70 days. Therefore, the spheromastigotes of T . cruzi seem to be induced by stress conditions.