ABSTRACT
Triatomine bugs are vectors for the Trypanosoma cruzi Chagas parasites, the etiological agent for Chagas disease. This study evaluated 6 epidemiologically significant behaviors (development time, number of blood meals required for molting to the next instar, mortality rate, aggressiveness, feeding duration, and defecation delay) across 4 populations of Triatoma mexicana Herrich-Schaeffer (Heteroptera: Reduviidae), a major T. cruzi vector in Central Mexico. We collected triatomines from areas characterized by high (HP), medium (MP), medium-high (MHP), and low (LP) prevalence of human T. cruzi infection. The MHP population had the shortest development time, <290 days. Both the HP and MP populations required the most blood meals to molt to the next instar, with a median of 13. Mortality rates varied across all populations, ranging from 44% to 52%. All of the tested populations showed aggressive behavior during feeding. All populations shared similar feeding durations, with most exceeding 13 min and increasing with each instar. Quick defecation, during feeding, immediately after or less than 1 min after feeding, was observed in most nymphs (78%-90%) from the MP and MHP populations and adults (74%-92%) from HP, MP, and MHP populations. Though most parameters suggest a low potential for T. mexicana to transmit T. cruzi, unique feeding and defecation behaviors in 3 populations (excluding the LP group) could elevate their epidemiological importance. These population-specific differences may contribute to the varying prevalence rates of T. cruzi infection in areas where T. mexicana is found.
ABSTRACT
We examined the degree of reproductive isolation in four populations of Triatoma mexicana Herrich-Schaeffer from Mexico along with fertility and the segregation of morphological characteristics in two generations of offspring from crosses between these populations. The percentage of couples with (fertile) offspring was high among all sets of crosses between cohorts from Peñamiller, Meztitlán, and Orizabita. It was low in crosses involving a cohort from Tierra Blanca, mainly in crosses with Meztitlán. Among sets of crosses involving Tierra Blanca specimens, whole first-generation (F1) individuals were morphologically similar to the specimens from other locations. All F1 individuals of crosses involving Peñamiller looked like Peñamiller. However, in crosses between F1 and F1 progeny of parental crosses, alleles for size, overall color, length of head, ante and post ocular distance, and humeral angle apparently had Mendelian dominant/recessive relationships. The cohorts from Peñamiller and Meztitlán seemed to be dominant with respect to Orizabita and Tierra Blanca. Results indicated that cohorts from Peñamiller, Meztitlán, and Orizabita were not reproductively isolated. In contrast, Tierra Blanca was reproductively isolated from the other three populations of T. mexicana and is apparently undergoing an early divergence process of speciation for allopatry.
Subject(s)
Chagas Disease , Triatoma , Triatominae , Animals , Triatoma/genetics , Fertility , MexicoABSTRACT
Clinical diagnosis of leishmaniasis is highly complex, presenting a wide range of clinical manifestations, sometimes non-specific, and thus the epidemiological study and diagnostic need specific molecular markers for each Leishmania species. Leishmania spp. posses different Fe-SOD isoforms, one of which is excreted into the external milieu and, presenting immunogenic characteristics, is a very reliable molecular marker. Superoxide dismutases (SODs) are antioxidant metal-enzymes responsible for the dismutation of superoxide ion into hydrogen peroxide and molecular oxygen, and it is considered an important virulence factor. In this manuscript we have purified the iron(Fe)-SOD excreted by Leishmania braziliensis using ion-exchange and molecular-sieve chromatography and we have studied it as an antigen in serodiagnostic analyses in ELISA and Western blot techniques, testing 213 human sera from Mexico. Indeed, L. braziliensis Fe-SODe has been purified 123.26 times with a specific activity of about 893.66 U/mg of protein. Applying the purified enzymes in serological tests we found 17.84% sera positive. We have demonstrated that the purified enzyme is more sensitive than the non-purified ones and we also demonstrated, for the first time, the presence of antibodies against L. braziliensis, not the main species in the country, in human population from Hidalgo and Nuevo Leon States.
ABSTRACT
The values of biological parameters related to the life cycles of four populations of Meccus longipennis (Reduviidae: Triatominae) were evaluated. Cohorts of each of the four studied populations from different geographical areas of Mexico were maintained under similar laboratory conditions and then compared. The population from El Saucito de Araujo was different from the other three studied populations, which could help explain the secondary importance of M. longipennis in the state of Chihuahua. This paper also supports the proposition that biological traits are important criteria for determining relationships between populations.
