Biological parameters of interbreeding subspecies ofMeccus phyllosomus(Hemiptera: Reduviidae: Triatominae) in western Mexico

Abstract

Understanding the biological parameters of some triatomine subspecies of Meccus phyllosomus (Burmeister) is a crucial first step in estimating the epidemiological importance of this group. Biological parameters related to egg eclosion, egg-to-adult development time, number of blood meals to moult, percentage of females at the end of the cycle, number of laid eggs, and the accumulative mortality for each instar of three M. phyllosomus subspecies [Meccus phyllosomus pallidipennis (Stål), Meccus phyllosomus longipennis (Usinger), and Meccus phyllosomus picturatus (Usinger)] as well as their laboratory hybrids were evaluated and compared. No significant differences (P > 0.05) were recorded among the experimental hybrids (M. p. longipennis × M. p. pallidipennis, M. p. longipennis × M. p. picturatus, M. p. pallidipennis × M. p. picturatus) and reciprocal cohorts. In five of the six studied parameters (egg eclosion, egg-to-adult development time, number of blood meals to moult, number of laid eggs and accumulative mortality), with the exception of the non-significant percentage of females obtained among all the studied cohorts, at least one of the parental cohorts in each set of crosses exhibited better fitness results than by those of their hybrid descendants. The lack of hybrid fitness in our study indicates the maintenance of reproductive isolation of parental genotypes. Moreover, the results lead us to propose that an incipient speciation process by distance is currently developing among the three studied subspecies, increasing the differences between them that modify the transmission efficiency of Trypanosoma cruzi to human beings in Mexico.

Enhancing fitness in offspring of crosses between two triatomine species

“…This could represent an advantage for hybrid descendants because the faster the nymphs turn into adults, the shorter the period required to increase the population size. Similar results were recorded for F1 hybrid offspring of the epidemiologically important Mexican species M. pallidipennis and M. picturatus as well as of M. phyllosomus and Triatoma recurva (Stål) (Martínez‐Ibarra et al , Díaz et al ). This latter species is considered as an important vector in the United States (Bern et al ).…”

“…As previously reported for T. recurva, M. phyllosomus , M. mazzottii, and their hybrids, death in the youngest nymphs seemed to be caused by inability to feed, as dead triatomines were generally found without substantial intestinal content. On the other hand, the death of older nymphs appeared to occur during molting (Martínez‐Ibarra et al , ). The percentage of adult females at the end of the life cycle was similar among three of the studied cohorts, except for M. bassolsae , which had a lower percentage.…”

Biological parameters of interbreeding populations of Meccus phyllosomus longipennis (Usinger), 1939 (Hemiptera: Reduviidae: Triatominae) in Mexico

“…This parameter also suggests the increased fitness of descendants of IP crosses. As previously reported for M. p. longipennis (Martínez-Ibarra et al 2015), death in the youngest nymphs seemed to be caused by inability to feed, as dead triatomines were generally found without substantial intestinal content. On the other hand, the death of older nymphs appeared to occur during molting.…”

“…In the descendant F1 cohorts of Sayula IP crosses (Penjamo x Sayula and La Palma x Sayula), egg eclosion rates were higher than those recorded for Penjamo and La Palma parental cohorts, which indicates an increase in fitness of descendants of IP crosses. A similar phenomenon was recorded when crosses of M. p. pallidipennis (Stål) x M. p. longipennis were carried out (Martínez-Ibarra et al 2015).…”

“…The median egg‐to‐adult development time for most of the studied cohorts was between five‐and‐a‐half and six months, similar to those for the related subspecies M. p. picturatus (Usinger) and M. p. pallidipennis (Martínez‐Ibarra et al ) In contrast, the development time was longer than six‐and‐a‐half months for the La Palma parental cohort. Interestingly, in both sets of IP crosses in which this last population was involved (Penjamo × La Palma and La Palma × Sayula), shorter median egg‐to‐adult development times were recorded compared to those for the La Palma parental cohort, showing a higher fitness of these descendants of IP crosses.…”