Comparative Analysis of Vectorial Capacity Among Triatoma brasiliensis brasiliensis, Triatoma juazeirensis, and Their Experimental Hybrids

The existence of a natural hybridization zone of members of the <i>Triatoma brasiliensis</i> complex in Pernambuco, a Brazilian state with areas highly infested by <i>Trypanosoma cruzi</i> vectors, raised questions to be studied about the vectorial capacity of these hybrids. Recently, it was demonstrated that experimental hybrids of <i>T. brasiliensis brasiliensis</i> and <i>Triatoma juazeirensis</i> present vectorial competence superior to that of the parental species. The objective of the present study was to compare bionomic aspects related to the vectorial capacity of <i>T. b. brasiliensis</i>, <i>T. juazeirensis,</i> and their experimental hybrids. Feeding and defecation behavior patterns in fifth instar nymphs were comparatively analyzed between four groups, two parental and two hybrids, respectively: <i>T. b. brasiliensis</i>, <i>T. juazeirensis</i>, Hjb (♀ <i>T. juazeirensis</i> × ♂ <i>T. b. brasiliensis</i>), and Hbj (♀ <i>T. b. brasiliensis</i> × ♂ <i>T. juazeirensis</i>). Fifteen newly molted fifth instar nymphs from each of the mentioned groups were previously subjected to a period of fasting for 10 days and individually kept in identified bottles. In the experiment, the insects were placed in a jar containing a mouse immobilized in nylon mesh, in accordance with the guidelines of the animal ethics committee. The following variables were observed: 1-total number of feedings carried out; 2-time to start feeding; 3-duration of feeding and weight acquired; 4-defecations during feeding; 5-defecation within one minute after cessation of feeding; 6-defecation within ten minutes after cessation of feeding; 7-defecation behavior. Specimens from all groups demonstrated voracity, starting their meal immediately after contact with the mouse, and most of the insects defecated immediately after feeding, with 78% of the insects defecating within 30 s. The results obtained suggest that <i>T. brasiliensis</i>, <i>T. juazeirensis</i>, and their experimental hybrids presented bionomic characteristics compatible with the species considered good vectors in the literature. However, <i>T. b. brasiliensis</i> and <i>T. juazeirensis</i> demonstrated even more effective characteristics for <i>T. cruzi</i> transmission regarding their feeding and defecation patterns when compared to their hybrids.