Effects of food source and feeding frequency on Chagasic bug (Triatoma pallidipennis) fitness

The effects of quality and frequency of blood ingested by insect vectors on their life histories arc crucial to interpret their feeding preferences in the field. Triatomine bugs act as vectors of the Chagas disease, feeding on blood during their entire lives. Earlier research has shown that compared to avian blood, mammal blood has positive effects on life history traits, as does having a higher frequency of feeding events. Using a factorial design, we investigated the effect of feeding on mammal blood, avian blood and defibrinated mammal blood, as well as the potential impact of feeding every 8 or every 45 days. The kissing bug Triatoma pallidipennis was selected as study species. The response variables considered here were the insect development time (i.e. from first instar nymph to adult), size, survival, and fecundity. Bugs fed with mammal blood did not differ from those fed with avian blood in how long it took to reach adulthood. Bugs were larger when fed with mammal blood, although there were differences between the sexes according to distinct size indicators. Survival was higher when the food source was bird rather than mammal blood, but the opposite occurred for fecundity. All traits were maximized when feeding was every 8 days, while the worst performances were achieved when bugs were fed with defibrinated blood every 45 days. These results suggest divergent effects in the relationship with blood source depending on the examined life history trait. This life history trait-specific maximization implies that T. pallidipennis may demand different food sources in the field. Results about other triatomines indicate species-specific host feeding preferences in nature that also maximize different traits, contributing to shedding light on the diversity of feeding preferences across triatomine vectors.