Studies in search of a suitable experimental insect model for xenodiagnosis of hosts with Chagas' disease. 4--The reflection of parasite stock in the responsiveness of different vector species to chronic infection with different Trypanosoma cruzi stocks.

Previous studies (1982, 1987) have emphasized the superiority of sylvatic vector species over domestic species as xenodiagnostic agents in testing hosts with acute or chronic infections by T. cruzi "Y" stock. The present study, which is unique in that it contains data on both infectivity rates produced by the same stock in 11 different vector species and also the reaction of the same vector species to seven different parasite stocks, establishes the general validity of linking efficiency of xenodiagnosis to the biotope of its agent.