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. 2025 Feb 10;16(2):188.
doi: 10.3390/insects16020188.

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

Keswick C Killets  1 , Jillian Wormington  1   2 , Italo Zecca  1 , Luis Fernando Chaves  3   4 , Gabriel L Hamer  5 , Sarah A Hamer  1
Affiliations

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

Keswick C Killets et al. Insects. .

Abstract

Triatomines are vectors of Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae), the agent of Chagas disease. Stercorarian transmission occurs when infectious parasites are passed in insect feces to vertebrates through the biting wound or mucosa. Defecating 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 min) than that of T. gerstaeckeri (9.75 ± 2.52 min) and T. sanguisuga (20.69 ± 8.98 min). Furthermore, the PFDI was shorter for TcI-infected insects compared to uninfected insects. Triatoma gerstaeckeri and T. sanguisuga are capable of stercorarian transmission, although the calculated metrics suggest they are less efficient vectors than R. prolixus.

Keywords: Trypanosoma cruzi; feeding and defecation behaviors; triatomines.

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Conflict of interest statement

The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

Figures

Figure 1
Figure 1
Flowchart of the methods used in experimental infections and the three methods for subsequent confirmation of infection status: abdominal compression, fecal spot testing, gut dissection testing. Illustration created in BioRender.
Figure 2
Figure 2
Boxplots of (A) number of feeding events per triatomine species: Rhodnius prolixus (Control, TcIV); Triatoma gerstaeckeri (Control, TcI, TcIV); Triatoma sanguisuga (Control, TcI); (B) total feeding times (min) per triatomine species: R. prolixus (Control, TcIV); T. gerstaeckeri (Control, TcI, TcIV); T. sanguisuga (Control, TcI); (C) total number of defecation events per triatome species: R. prolixus (Control, TcI, TcIV); T. gerstaeckeri (Control, TcI, TcIV); T. sanguisuga (Control, TcI); (D) post-feeding defecation interval (min) of the first defecation per triatomine species: R. prolixus (Control, TcIV); T. gerstaeckeri (Control, TcI, TcIV); T. sanguisuga (Control, TcI).
Figure 3
Figure 3
Boxplot showing each individual post-feeding defecation intervals (min) between the most recent bloodmeal and defecation per triatomine species: Rhodnius prolixus (Control, TcIV); Triatoma gerstaeckeri (Control, TcI, TcIV); Triatoma sanguisuga (Control, TcI). Triatomines that defecated multiple times have multiple data points in the plot.
Figure 4
Figure 4
Photographs of all three species of triatomines simultaneously defecating while feeding on restrained guinea pigs. Left to right: Triatoma gerstaeckeri, Triatoma sanguisuga, Rhodnius prolixus.
Figure 5
Figure 5
Defecation indices (DI = (% of insects that defecated up to 10 min post feeding X average number of defecations up to 10 min post feeding)/100)) of each infection group.
See this image and copyright information in PMC

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