Heteropyknotic filament in spermatids ofTriatoma melanocephalaandT. vitticeps(Hemiptera, Triatominae)

Spermatological Morphology of Triatoma Species (Hemiptera: Reduviidae: Triatominae)

Spermatozoa are among the most diverse cell types, and their morphologies often provide data that can be used to reliably evaluate phylogenetic relationships. They can also help to clarify the nature of 'specific complexes', which are common among triatomines. In the present study, we evaluated the copulation behavior of Triatoma rubrovaria Blanchard 1843 (Hemiptera: Reduviidae: Triatominae) and the structural morphology of sperm from T. carcavalloi Jurberg Rocha & Lent, 1998, T. infestans Klug, 1834, T. pintodiasi Jurberg Cunha & Rocha, 2013, and T. rubrovaria. Copulatory behavior was described from the moment males and females genitalia joined until they separated. Insemination was confirmed by the presence of a spermatophore in the female's bursa copulatrix. To measure their sperm, males were dissected and their seminal vesicles were removed, squashed on glass slides, and then spread, fixed, and observed under a photomicroscope. The images obtained were analyzed to measure the sperm. Seminal vesicles were also prepared for transmission electron microscopy. We performed K-means clustering separately for each species to group their sperm based on morphology. The differences in spermatozoa length among species of Triatominae, sperm types, and the interaction between species and sperm type were assessed with a two-way analysis of variance (ANOVA). The copulation time in T. rubrovaria was 3 to 5 min, which was sufficiently long for spermatophore transfer. All taxa showed polymorphic (short and long) sperm, with significant differences in the lengths of sperm among taxa. Using electron microscopy, the sperm cells of the four taxa examined were found to have similar ultrastructural morphology, confirming the hypothesized synapomorphies of sperm within the suborder Heteroptera (Hemiptera).

Sperm dimorphism in the Triatoma brasiliensis species complex and its applications

Morphological and structural features of the sperm of the Triatoma brasiliensis Neiva, 1911 (Hemiptera: Reduviidae) species complex were examined in this first study investigating the sperm of Heteroptera and the genus Triatoma. Males were dissected and their seminal vesicles removed. For measurement, seminal vesicles were squashed on glass slides, spread, fixed and observed under a photomicroscope. The images were analysed and measures of sperm were made. Data were analysed using one-way analysis of variance and Tukey's test to detect differentiation among taxa. Furthermore, seminal vesicles were prepared for studies of transmission electron microscopy. All taxa studied showed polymorphic (short and long) sperm. The sperm of Triatoma brasiliensis macromelasoma was significantly longer (in total length) than that of the other four members of the complex, which supports the hypothesis of hybrid speciation of this member of the complex as an increase in the size of typical hybrids under heterosis was previously shown. The sperm cells of the five taxa have similar ultrastructural morphology. The ultrastructural features observed confirm the hypothesis, raised by previous studies, that they are synapomorphic to the suborder Heteroptera.

Reproductive Biology of Triatoma brasiliensis (Hemiptera, Triatominae) During the Imaginal Molt

The triatomines are vectors of the protozoan Trypanosoma cruzi, etiologic agent of Chagas disease. These insects are sexually active after the imaginal molt. Some aspects have been studied in Triatoma brasiliensis during the imaginal molt, such as autogeny in virgin females and the relationship between blood ingestion by fifth instar nymph and the realization of the imaginal molt. Thus, to aid in the understanding of reproductive biology and developmental physiology of these vectors, this article analyzes the spermatogenesis of T. brasiliensis during the imaginal molt. The analysis of the seminiferous tubules from males in the fifth instar during imaginal molt has demonstrated that T. brasiliensis has only a few spermatids and a plentiful quantity of sperm. Thus, we suggest that during imaginal molt the cell division is disrupted aiming to reduce energy costs and the differentiation into sperm is stimulated to ensure the paternity of the adult male.

Immunofluorescence and ultrastructural analysis of the chromatoid body during spermatogenesis of Triatoma platensis and T. rubrovaria (Hemiptera, Triatominae)

This study sought to analyze spermatogenesis in two species of triatomines (Triatoma rubrovaria and T. platensis) by focusing on the chromatoid body (CB) during three stages of spermatogenesis (spermatocytogenesis, meiosis, and spermiogenesis). The cytochemistry technique known as silver impregnation revealed nucleolar persistence. We suggest that this phenomenon is fundamental to the formation of the CB during spermatogenesis, as it allows for the nucleolus or nucleolar fragments to maintain their transcriptional activity during the entire meiosis phase and to apply all transcribed RNA to CB formation. The ultrastructural analysis of T. platensis and T. rubrovaria spermatids revealed the presence of the nucleolus within the spermatid nucleus, as well as the CB near the nuclear membrane. Immunofluorescence for fibrillarin revealed the presence of protein in both the nucleolus and the cytoplasm of spermatogonia. Based on these findings, we suggest that the formation of the CB begins during the first phase of spermatogenesis, or spermatocytogenesis. Furthermore, we also observed the presence of fibrillarin protein in the CB near the elongating spermatids. Unlike the spermatogonia, spermatids showed no fibrillarin markings in the nucleolar region, a finding which is consistent with the lack of post-meiotic transcriptional activity during triatomine spermiogenesis. Thus, this study suggests that the formation of the CB begins during spermatocytogenesis and is intensified by transcriptional activity when nucleolar persistence occurs in meiosis. Moreover, the findings are consistent with the absence of transcriptional activity in the nucleolus during spermiogenesis, and they demonstrate that all transcriptional activity during spermatid differentiation is supported by the CB.

Coloration of the testicular peritoneal sheath as a synapomorphy of triatomines (Hemiptera, Reduviidae)

Recently, were described some morphological characteristics of 18 species of terrestrial hemipteran grouped in the Alydidae, Coreidae, Corimelaenidae, Lygaeidae, Rhopalidae, Scutelleridae, Tingidae and Reduviidae family that presented found variation in coloration of testicular peritoneal sheath (Reddish, Orange, Yellowish or Transparent). Thus, this study aims to analyzed the coloration of the peritoneal sheath in 44 species of triatomines grouped in nine different genera, with the aim of analyze whether the insects of the Triatominae subfamily also show variations in coloration. By means of analysis of the sheath was possible to observe that members of this subfamily have no interspecific differences, because all species have a transparent sheath. Thus, this paper describes the coloring of the peritoneal sheath in 44 species of the subfamily Triatominae and mainly suggests that the transparent color is one synapomorphy of this important group of insect vectors.