Biological behavior of triatomine species Triatoma brasiliensis and Triatoma pseudomaculata (Hemiptera: Reduviidae) infected with different DTUs (Discrete Typing Units) of Trypanosoma cruzi
Trypanosoma cruzi. Triatomines. Experimental infection. Discrete typing units. Biological aspects.
In the state of Rio Grande do Norte (RN), the species Triatoma brasiliensis and Triatoma pseudomaculata are found colonizing anthropic and wild environments, with high rates of natural infection by Trypanosoma cruzi and different DTUs (Discrete typing units) identified. Studies related to the biological aspects of triatomines infected with different T. cruzi isolates contribute to a better understanding of the vectorial capacity of certain species and may contribute to the development of more efficient vector control strategies. In this study we evaluated the influence of experimental infection of T. brasiliensis and T. pseudomaculata by different T. cruzi DTUs and the biological aspects of these vectors. T. brasiliensis and T. pseudomaculata nymphs were infected with RN isolates (RN02 and RN23) and the clone CL-Brener, forming the following groups: Group 01 (non-infected insects); Group 02 (CL-Brener); Group 03 (RN02); Group 04 (RN23); Group 05 (RN02+RN23); Group 06 (RN02+RN23+CL-Brener), with blood meal every 15 and 30 days. The infection of triatomines by T. cruzi was evaluated daily and individually. The analysis of biological aspects of insects was performed daily, fortnightly and monthly. In insects that underwent a blood meal every 15 days, a high number of evolutionary forms of the parasite was observed in group 03 (RN02) of T. brasiliensis (1,127.7×102/5μL) and in group 06 (RN02+RN23+CL-Brener) of T. pseudomaculata with 834.7×102/5μL. In feeding every 30 days, in group 05 (RN02+RN23) of T. brasiliensis and T. pseudomaculata, high numbers of evolutionary forms of T. cruzi were observed, 1,501.3×102/5μL and 115.5×102/5μL, respectively. In groups fed every 15 days, the percentage of T. cruzi infection in groups 05 (RN02+RN23) of T. brasiliensis and 03 (RN02) of T. pseudomaculata was 30% and 40%, respectively. In groups fed every 30 days, the percentage of infection in groups 03 (RN02) of T. brasiliensis and 06 (RN02+RN23+CL-Brener) of T. pseudomaculata was 30% and 20%, respectively. Blood intake was higher in T. brasiliensis in both blood meal periods. The percentage of insect excretion in the groups fed every 15 days was 78% for group 04 (RN23) of T. pseudomaculata 15 d.p.i. and in groups fed every 30 days, group 03 (RN02) of both T. brasiliensis and T. pseudomaculata the percentage was 100% and 85%, respectively. The weight of triatomines 4h after feeding was reduced due to excretion in both species. The percentage of occurrence of ecdysis varied from 40 to 70% in T. brasiliensis groups and from 10 to 30% in T. pseudomaculata fed every 15 days. While in the groups fed every 30 days, the percentage ranged from 20 to 60% in the T. brasiliensis groups and from 30 to 50% in the T. pseudomaculata groups. Triatomine mortality was higher in the groups of T. brasiliensis and T. pseudomaculata fed every 30 days. The occurrence of kleptohematophagy in T. brasiliensis was identified during the blood meal. These data showed that the susceptibility of T. brasiliensis to infection by different isolates of T. cruzi was higher than that of T. pseudomaculata, reinforcing the importance of continuous entomological surveillance activities to prevent transmission of the parasite in areas of occurrence of this vector.