Membrane feeding for infection of the reduviid bug Triatoma infestans with Blastocrithidia triatomae (Trypanosomatidae) and pathogenic effects of the flagellate.

To investigate the pathogenic effects of the trypanosome Blastocrithidia triatomae on Triatoma infestans, a method for direct infection by in vitro feeding was developed. After isolation of B. triatomae cysts from infected dead bugs, a suspension of cysts was disinfected with Desogen and Chloramin T, then mixed with sterile blood, spread on a sterile, parallel-grooved glass plate or a hammered aluminium plate and covered with a thin, sterile silicone membrane. The blood and plate were warmed to 36 degrees-38 degrees C by a heating plate. For investigation of the pathological effects, first instars of T. infestans were allowed to feed through the membrane on a mixture containing 10(6) cyst stages/cm3 blood. Development of about 30% of the third and fourth instar larvae was retarded as compared with that in uninfected control groups, and mortality rates increased in fourth and/or fifth instar larvae. Whereas total mortality rates of about 5% occurred in control groups, about 85% of the larvae died in the infected groups. These effects are very similar to those obtained in previous studies with coprophagic infections.