Effects of the quality and frequency of blood feeding on the immune response of <i>Triatoma pallidipennis</i> , a Chagas disease vector

Abstract Triatoma pallidipennis is a vector of Trypanosoma cruzi , the causative agent of Chagas disease. These insects feed on a diverse range of vertebrate hosts, including mammals, birds and other animals, with variations in blood source influencing their immune response and fitness. We analysed the effect of the source and frequency of blood feeding on the immune response of T. pallidipennis . Three blood sources were used: mammalian (rabbit), bird (chicken) and defibrinated mammalian blood (rabbit). Food was provided at periods of 8 and 45 days to first instar nymphs until adulthood. Once they reached adulthood, the insects were challenged with Escherichia coli , and the expression of antimicrobial peptides (AMPs) defensin B and prolixicin was quantified. Results show that feeding on mammalian blood at short intervals (every 8 days) significantly upregulated both AMPs, with a strong immune response observed in comparison to insects fed avian or defibrinated blood. Prolixicin expression was more consistently induced across different conditions, whereas defensin B expression was more dependent on blood type and feeding frequency. These results indicate that both the type of blood and the frequency of feeding play crucial roles in modulating the immune response in T. pallidipennis , suggesting that mammalian blood enhances immune capacity and may influence the vectorial capacity for transmitting T. cruzi . We highlight the importance of blood meal composition and feeding intervals in shaping immune responses and provide insights into the ecological factors that influence triatomine immune competence and disease transmission dynamics.