Bacteria cultured from the gut of Meccus pallidipennis (Hemiptera: Reduviidae), a triatomine species endemic to Mexico.

The study of intestinal microbiota in vector insects like triatomines is paramount in parasitology because many parasitic species inhabit the vector's gut. Although knowledge on the gut microbiota in various vectors of the parasitic flagellate Trypanosoma cruzi has grown, research efforts have focused on South American triatomines. This study reports the isolation of bacterial microbiota in the anterior and posterior gut of Meccus pallidipennis (a triatomine species endemic to Mexico) by culture, as well as its identification by phenotypic and biochemical tests and its quantification by counting colony-forming units. The study was performed on fifth-instar nymph and adult specimens of M. pallidipennis, either laboratory-bred or collected in the field and either infected or not with T. cruzi. Overall, 17 bacterial species were identified, with the genera Bacillus and Staphylococcus being the most prevalent regardless of the origin of the insects. No differences were observed in the number of bacterial species in the gut of laboratory-bred and field-collected insects, neither with respect to life stage or infection status. In general, the Shannon-Weaver diversity index was higher in non-infected insects than in infected ones. Further studies using non-culture methods are required to determine whether bacterial species diversity is modified by laboratory breeding.

Transmission Capacity of Trypanosoma cruzi (Trypanosomatida: Trypanosomatidae) by Three Subspecies of Meccus phyllosomus (Heteroptera: Reduviidae) and Their Hybrids.

Three behaviors of epidemiological importance: the time lapse for the onset of feeding, actual feeding, and defecation time for Meccus phyllosomus pallidipennis (Stål), Meccus phyllosomus longipennis (Usinger), Meccus phyllosomus picturatus (Usinger), and their laboratory hybrids were evaluated in this study. The mean time lapse for the beginning of feeding was between 0.5 and 8.3 min considering all instars in each cohort, with highly significant differences only among fifth-instar nymphs, females, and males of M. p. pallidipennis and M. p. longipennis relative to the hybrid cohorts. Four hybrid (LoPa [M. p. longipennis and M. p. pallidipennis] and LoPi [M. p. longipennis and M. p. picturatus] and their reciprocal experimental crosses) cohorts had similar mean feeding times to one of the parental subspecies, but longer than the other one. The remaining hybrid cohort (PaPi [M. p. pallidipennis and M. p. picturatus]) had longer feeding times than both of its parental subspecies. The specimens of the LoPa and LoPi hybrid cohorts defecated faster than the respective instars of the three parental cohorts. With exception of first- and fifth-instar nymphs, PaPi cohorts defecated faster than the remaining seven cohorts. More than 60% of defecation events occurred during feeding in the six hybrid cohorts. Our results indicate that hybrid cohorts have more potential to acquire infection and transmit Trypanosoma cruzi Chagas than their parental cohorts.