Comparison of feeding and defecation patterns of Rhodnius colombiensis and Rhodnius prolixus(Hempitera, Reduviidae, Triatominae) under laboratory conditions

Rhodnius colombiensis occasionally comes into human dwellings and consequently its role as an important potential vector in the transmission of American trypanosomiasis has been suggested. The potential role of R. colombiensis as vector was defined by comparing the feeding and defecation patterns between R. colombiensis and R. prolixus, the main domiciliary vector of Trypanosoma cruzi in Colombia. MATERIALS AND METHODS. For each developmental stage of R. colombiensis and R. prolixus the following data were collected: (1) time of feeding initiation, (2) the time for reaching the repletion, (3) the number of interruptions and defecations during the feeding, (4) the time between the end of the feeding and the first defecation, (5) the number of defecations during 10, 60 and 95 minutes of observation after feeding, and (6) the quantity of blood ingested. The mean time of feeding initiation of the fifth instar nymphs, males and females, showed significant differences between the two species. The average of insects that defecated within 10 minutes after feeding was higher for each successive stage of R. prolixus and showed significant differences with Rhodnius colombiensis. In contrast, the mean weight of blood ingested by each stage of R. colombiensis and R. prolixus was significantly different between the N1, N2, N5 and females of these species. Rhodnius colombiensis produced fewer defecations than R. prolixus during feeding. A higher percentage of R. prolixus defecated within 10, 60 and 95 minutes after feeding. However, R. colombiensis remains a longer time in contact with the vertebrate host, thus raising the probability of its role in transmission considering its occasional entry to human dwellings and its higher prevalences of infection withT. cruzi and T. rangeli.