Genetic studies of Psammolestes tertius (Hemiptera : Reduviidae : Triatominae) using male genital morphology, morphometry, isoenzymes, and random amplified polymorphic DNA

Two Brazilian populations of Psammolestes tertius (Ceara and Minas Gerais) collected from thornbird nests (Furnariidae) were compared by male genital morphology, morphametry, isoenzymes, and random amplified polymorphic DNA (RAPD). Merle genitalia showed no difference between the populations. In contrast, morphometry, isoenzyme, and RAPD clearly distinguished the two populations. Possible mechanisms of dispersal and the origin of Psammolestes are discussed.

Acid phosphatase activity distribution in salivary glands of triatomines (Heteroptera, Reduviidae, Triatominae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Chromosomal location of heterochromatin and 45S rDNA sites in four South American triatomines (Heteroptera: Reduviidae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cytochemical characterization of Triatoma infestans and Panstrongylus megistus salivary gland cells (Hemiptera, Reduviidae, Triatominae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cytogenetic characterization reveals differences in nuclear organization of cystic cells among Brazilian species of Triatoma (Heteroptera, Reduviidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Description of Rhodnius montenegrensis n. sp (Hemiptera: Reduviidae: Triatominae) from the state of Rondonia, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A study of the scutellum in eight Chagas disease vector species from genus Triatoma (Hemiptera, Reduviidae) using optical and scanning electron microscopy

The aim of this study was to analyze the external morphology of the scutellum through optical microscopy and scanning electron microscopy (SEM) in male specimens of Triatoma costalimai, T. delpontei, T. eratyrusiformis, T. matogrossensis, T. infestans melanosoma, T. sherlocki, T. tibiamaculata, and T. vandae. A total of 30 photographs of the scutellum were made. Magnification varied from 50X to 750X. Regarding depth and forms of the central depression, the heart-shaped form was predominant, with some exceptions, so that this shape appears to be a common characteristic for species of genus Triatoma Laporte, 1832. In T. eratyrusiformis, a kind of sensillum with important taxonomic value was observed. The different sizes and shapes of the designs found on the posterior process of the scutellum were also of important taxonomic interest. The study of the scutellum based on SEM showed valuable characteristics, allowing the use of this structure to aid the diagnosis of triatomine species. Thus, more specimens in subsequent studies and analyses of morphometric parameters should contribute to agreement on phylogenetic aspects in this genus. A Key to eight species of Triatoma based on male scutellar morphology is presented.

Morfologia de ovos de Triatoma circummaculata e Triatoma rubrovaria (Hemiptera, Reduviidae)

OBJETIVO: Estudar morfologicamente ovos de T. circummaculata e T. rubrovaria. MÉTODOS: Quarenta ovos das duas espécies foram mensurados por meio de projetor de perfil Nikon modelo 6C, e utilizado o teste Student, para execução da análise estatística. As observações morfológicas foram feitas em microscópio eletrônico de varredura JEOL, modelo JSM-T330A. RESULTADOS/CONCLUSÕES: A análise estatística revelou que os ovos e as cascas de ovos de T. rubrovaria são significativamente maiores que os de T. circummaculata. Observações microscópicas mostraram que a borda corial, assim como a goteira espermática, são bem mais evidentes nos ovos de T. rubrovaria que nos de T. circummaculata. O exocório das duas espécies é formado por áreas poligonais, que são hexagonais em sua maioria. Foram observados também o momento da eclosão do embrião e os detalhes das exúvias embrionárias.

Pattern of nucleolar activity during spermiogenesis in triatomines (Heteroptera, Reduviidae) as analysed by silver staining

Nucleoli are the sites of biosynthesis of ribosomal precursors. In this work the nucleolar activity at interphase and the meiotic cells of the testis in five species of triatomines were analysed by means of silver staining. Several nucleolar blocks in the polyploid nuclei of testicular tubules were observed, whereas only one nucleolar body could be seen in the spermatogonial nuclei of all five species. A single nucleolar body was evident in the 'confused stage' of Triatoma brasiliensis, T. delpontei, T. lecticularia and T. rubrovaria, while T. sordida presented two nucleolar dots. The existence of small, silver-stained dots in some metaphase I chromosomes of T. brasiliensis and T. sordida is reported. The number of nucleolar dots present in spermatids of each species varied within and among species. It is suggested that in addition to providing information on rRNA biosynthesis, studies of nucleolar organizing activity can also be important sources of data on differentiation patterns and species development.

SEXUAL DISTINCTION BETWEEN 5TH INSTAR NYMPHS OF 6 SPECIES OF TRIATOMINAE (HEMIPTERA, REDUVIIDAE)

The aim of this paper is to present the analysis of sexual morphological differences observed in 5th instar nymphs of the following species: Panstrongylus megistus; Rhodnius neglectus; Triatoma brasiliensis; T. infestans; T. matogrossensis and T. tibiamaculata. Male and female nymphs were examined and photographed with a Scanning Electron Microscope. The 9th segment dimensions of dorsal and ventral faces were determined through a Profile Projector. Results and statistical analysis showed significant differences: the 9th sternite is significantly broader in male than in female nymphs, while in five species, tergites in female nymphs are broad and in male are narrow.

Cytogenetic studies on holocentric chromosomes of five species of triatomines (Heteroptera: Reduviidae)

The chromosome number and meiotic cycle of triatomines were investigated. All five species presented the same diploid chromosome number, 2n = 22 (20A + XY in the male). Phylogenetic relationships based on chromosomal evidence and C-banded karyotypes in the subfamily are discussed. It is suggested that differences in DNA content are mainly due to variations in the amount of C-heterochromatin, which may be interpreted as loss and/or gain of C-regions. This interpretation is supported by the presence of meiotic and mitotic chromocentres which facilitate the transfer of C-positive material.

Estudo biológico e morfométrico dos estádios ninfais de Rhodnius neglectus Lent, 1954 (Hemiptera, Reduviidae)

The following parameters of the biological cycle of the Rhodnius neglectus were determined under a temperature of 28°C and relative humidity of the air varying between 52-94%: a) average period of incubation: 13.67 days; b) rate of the eggs eclosion: 86.18%; c) average period of growth of the 1st, 2nd, 3rd, 4th, 5th instar nymphs: 18.91, 15.19, 21.38, 21.34, 30.43 days, respectively; d) percentage of death in the instar nymphs: 13.82, 18.26, 9.95, 8.78, 15.06% respectively; e) percentage of changes per instar nymphs: 86.18, 81.74, 90.05, 91.22, 84.94% respectively. The morphometric study with the stereoscopic microscope and Leica image analyses system, using the Qwin software, of the five instar nymphs showed that in the five instar nymphs a gradual growth of the head, thorax and abdomen occurs. In all the instars the abdomen is the largest segment. In the four first instars the head is larger than the thorax. In the fifth instar the head and the thorax present equivalent sizes.

Cytogenetic study on three species of the genus Triatoma (Heteroptera: Reduviidae) with emphasis on nucleolar organizer regions

The use of banding techniques allows the recognition of chromosomal pairs and karyotypical arrangements. However, its application in Heteroptera holocentric chromosomes is limited. Thus, little is known about their structure, specially their Nucleolar Organizer Regions (NORs). A comparative analysis of the nucleolar characteristics present during spermatogenesis in Triatoma platensis, Triatoma protacta and Triatoma tibiamaculata seems to indicate that in this group of insects nucleolar fragmentation occurs after prophase I. The study of chromosomal structure of these triatomines indicates that NORs are located at some telomeric and interstitial autosome regions and at sexual chromosomes (X/X1X2).

Estudo biológico e biométrico dos estádios ninfais de Rhodnius prolixus Stäl, 1859 (Hemiptera, Reduviidae) sob condições laboratoriais

Eggs and nymphs originated from couples of Rhodnius prolixus obtained from nymphs of the 5th instar were used for biological cycle and biometric studies. The following biological cycle parameters were determined under a temperature of 28°C and relative humidity, varying between 52 - 94% : medium period of incubation: 13.01 days; rate of eggs eclosion: 77.6%; medium period of development of the 1st, 2nd, 3rd, 4 th, 5th instar nymphs : 19.33, 19.09, 20.38, 24.37, 38.14 days, respectively; percentual of deaths in the nymph instar: 26.70, 14.00, 18.26, 17.02, 35.47% respectively; percentual of changes per instar nymphs; 73.30, 86.03, 81.73, 82.97, 64.52%, respectively. Biometric measurements performed, showed that in all the instars the abdomen is the largest segment. In the four first instars, the head is larger than the thorax. In the fifth instar, the head and thorax present are about the same size.