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.

Biological and genetic aspects of crosses between phylogenetically close species of Mexican triatomines (Hemiptera: Reduviidae).

Reproductive isolation between Triatoma mexicana (Herrich-Scaeffer) and the six species of the Phyllosoma complex, belonging to the genus Meccus, was examined by analyzing the fertility of experimental hybrids. The percentage of couples with offspring was highest in the set of crosses between Meccus phyllosomus (Burmeister) and T. mexicana, and lowest in those between Meccus pallidipennis (Stål) and Meccus bassolsae (Alejandre-Aguilar, Nogueda-Torres, Cortés-Jiménez, Jurberg, Galvão, and Carcavallo) with respect to T. mexicana. Crosses between Meccus mazzottii (Usinger), Meccus picturatus (Usinger), and Meccus longipennis (Usinger) and T. mexicana had scarce offspring, whereas offspring from crosses between M. phyllosomus and T. mexicana were abundant. However, all F1 nymphs died in different instars before reaching sexual maturity. The biological evidence in this study suggests that different degrees of reproductive isolation exist between T mexicana and the different species of Meccus. Our data also support the current status of T. mexicana as a separate species.

Inhibition of neutrophil chemotaxis by pig seminal plasma in vitro: a potential method for modulating post-breeding inflammation in sows.

The aim of this study was to determine the regulatory role of pig seminal plasma in post-breeding uterine inflammation. Polymorphonuclear neutrophil (PMN) chemotaxis of lipopolysaccharide (LPS)-activated blood plasma or heat-inactivated blood plasma plus LPS containing increasing concentrations of seminal plasma was assessed in chemotactic chambers. Seminal plasma was diluted serially with McCoy's medium to concentrations of 50.0, 25.0, 12.5, 6.2 or 3.1% (v/v) and added to normal or heat-inactivated pig blood plasma that was activated with LPS before or after incubation in a 37 degrees C waterbath for 30 min. Chemotaxis was determined using blood-derived PMNs and was expressed as a percentage of the positive control of LPS-activated blood plasma. A linear dose-dependent suppression of chemotaxis by seminal plasma was observed for blood plasma activated before or after addition of seminal plasma. Compared with the positive control, concentrations of seminal plasma < 6.2% failed to suppress PMN chemotaxis (P < 0.05). A dose-dependent suppressive effect of seminal plasma on heat stable chemotactic components of pig blood plasma was also observed (P < 0.05). A marked suppression was observed at concentrations of seminal plasma > 12.5% of the sample volume (P < 0.05). These results indicate that seminal plasma suppresses chemotactic blood plasma components regardless of formation sequence (pre- or post-activation) or source (normal or heat-inactivated blood plasma). These results indicate that seminal plasma may be necessary in diluted boar semen used for artificial insemination to regulate post-breeding inflammation in sows.