Comparative Feeding and Defecation Behaviors of Trypanosoma cruzi-Infected and Uninfected Triatomines (Hemiptera: Reduviidae) from the Americas

Triatomines are vectors of Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae), agent of Chagas disease. Stercorarian transmission occurs when infectious parasites are passed in insect feces to vertebrates through the biting wound or a mucosa. Defaecating on hosts during or shortly after blood-feeding is therefore critical for transmission, and delayed triatomine defecation behavior has been posited to contribute to a low incidence of human Chagas disease in the U.S. We allowed nymphal T. cruzi-infected and uninfected Triatoma gerstaeckeri (Stål, 1859) and Triatoma sanguisuga (LeConte, 1855) to interact with restrained guinea pigs and measured insect feeding and defecation events; South American Rhodnius prolixus (Stål, 1859; Latin America) served as a comparison group. In 148 trials, 40.0% of insects fed, of which 71.2% defecated. Compared to R. prolixus, T. gerstaeckeri had >9 times higher odds of feeding, and T. sanguisuga fed longer. Observations of defecation while feeding occurred across all three species. The post-feeding defecation interval (PFDI) of R. prolixus was significantly shorter (4.54±2.46 minutes) than that of T. gerstaeckeri (9.75±2.52 minutes) and T. sanguisuga (20.69±8.98 minutes) and the PFDI between was shorter for TcI-infected insects. Triatoma gerstaeckeri and T. sanguisuga are capable of stercorarian transmission, although the calculated metrics suggest they are less efficient vectors than R. prolixus.