Morphology of the spermatheca of Triatoma lecticularia (Hemiptera: Reduviidae) (Stal, 1859) / Morfologia da espermateca de Triatoma lecticularia (Hemiptera: Reduviidae) (Stal, 1859)

Abstract Triatoma lecticularia (Hemiptera: Reduviidae) (Stal, 1859) is a potential vector of Chagas's disease and the comprehension of its reproductive biology is an important tool to control this insect. In the reproductive tract of female insects, the spermatheca plays a crucial role storing male spermatozoa after mating. Whithin insects the spermatheca shows a wide morphological diversity and the analysis of this characteristic can contribute to understand the reproductive biology of the species. This study describes the histology and histochemistry of the spermatheca of T. lecticularia. Females have a pair of elongated spermathecal reservoirs without associated accessory gland. The reservoir opens into the common oviduct via a narrow muscular duct. The reservoir epithelium has single layer of columnar secretory cells. The control of the release of spermatozoa from the spermatheca occurs via the muscular duct. The anatomical features of the spermatheca of T. lecticularia resemble those described of other Reduviidae. However, the histological and histochemical features of spermatheca observed in T. lecticularia were important to explain the maintenance of the viability of the spermatozoa stored.

Resumo Triatoma lecticularia (Hemiptera: Reduviidae) (Stal, 1859) é um potencial vetor da doença de Chagas e a compreensão de sua biologia reprodutiva é um importante fator para seu controle populacional. No aparelho reprodutor feminino dos insetos, a espermateca desempenha a importante funcão de armazenar os espermatozoides após cópula. Nos insetos, a espermateca apresenta uma ampla diversidade morfológica e a análise destas características pode contribuir com o entendimento da biologia reprodutiva das espécies. Este estudo descreve histológica e histoquimicamente a espermateca de T. lecticularia. As fêmeas tem um par de espermatecas alongadas sem glândulas acessórias associadas. O reservatório conecta-se ao oviduto comum através de um ducto muscular curto que controla a liberação dos espermatozoides. O epitélio do reservatório possui uma camada de células secretoras colunares. As características anatômicas da espermateca de T. lecticularia são semelhantes às encontradas em outros Reduviidae. Entretanto, as características histológicas e histoquímicas observadas na espermateca são importantes para explicar a manutenção da viabilidade dos espermatozoides armazenados.

Differentiation and morphogenesis of Triatoma infestans (Klug 1834) female gonads. I- Post embryonic development

The post-embryonic development of the female gonads in Triatoma infestans (Hemiptera, Heteroptera), insects of importance in health affairs as harbors and vectors of different tripanosomatidea flagellates, is presented in a complete follow-up since insect hatches from the egg up to the last molt in the fifth instar stage. The detailed description of the morphological changes which occur in each instar as well as careful measurements evaluating its size increase have been analyzed by stereomicroscopy, phase contrast, dark field, and oblique ilumination, in order to optimize the observations as well the photographic register of gonad morphology and structure. The analysis was performed on gonad specimens obtained from broods no less than twenty (20) nymph bugs, reared at constant temperature and fed-up regularly. According to the results of our study we can assert that gonad differentiation takes place in early phases of the insect development. Such is tge case that first instars nymph´s present absolutely and easily recognizably male and female gonads. From the third instar on beside the filament region, the three zones in each ovariole body is distinguished, a differentiation that is more noticeable during the fourth instar where a definite organization is present at the vitelarium. Such a clear cut zone development continues intensively during the fifth instar. Finally at the end of such fifth nymph stage and when the last molt toward adults is prepared, clear signs of ovariole maturation take place since oocytes in early vitelogenesis are found.

Chromosome homogeneity in populations of Triatoma brasiliensis Neiva 1911 (Hemiptera - Reduviidae - Triatominae)

Têm-se reportado a ocorrência de quatro padröes cromáticos e diferentes padröes morfológicos, genéticos e ecológicos de Triatoma brasiliensis no semi-árido nordestino do Brasil, regiäo onde é o mais importante vetor da doença de Chagas. Para verificar diferenças citogenéticas nessas populaçöes, foram analisados seus cariótipos e o comportamento cromossomial durante o processo meiótico em exemplares machos. Observou-se que o T. brasiliensis mostra características cromossômicas distintas e específicas entre as quatro populaçöes, diferindo daquelas observadas em outras espécies de triatomíneos. No entanto, diferenças citogenéticas näo foram observadas entre as quatro populaçöes de T. brasiliensis, o que poderia indicar que as referidas populaçöes ainda se encontram em uma etapa inicial do processo de diferenciaçäo, ainda näo envolvendo a organizaçäo cromossomial.

Mitochondrial DNA variation of Triatoma infestans populations and its implication on the specific status of T. melanosoma

DNA sequence comparison of 412 base-pairs fragments of the mitochondrial cytochrome B gene was used to infer the genetic structure of nine geographical Triatoma infestans populations and their phylogenetic relationship with T. melanosoma and T. brasiliensis. T. infestans and T. melanosoma were compared by morphometry, allozyme and cytogenetic analyses, as well as subjected to reciprocal crosses, in order to clarify the taxonomic status of the latter. No differences were found to distinguish the two species and the crosses between them yielded progeny. T. infestans populations presented four haplotypes that could be separated in two clusters: one formed by the samples from Bolivia (Andes and Chaco) and the other formed by samples from Argentina and Brazil. Silvatic and domestic T. infestans populations from Bolivia (Andes) were genetically identical.

Morfologia externa de Triatoma ryckmani Zeledón & Ponce, 1972 vista através da microscopia eletrônica de varredura / External morphology of triatoma rickmani Zeledón & Ponce, 1972 by scanning electron microscopy

A male of Triatoma ryckmani Zeledón & Ponce, 1972, was studied by scanning electron microscopy. Only few specimens of this species are known. In this paper, some structures from the head, thorax, abdomen and distal region of the second leg are shown. Some of them could have taxonomic importance, as the oculo-ocellar region, the buccula, the anterolateral angle of the collar, the scutellum with the process longer than the main body, the stridulatory sulcus with an unusual backward vermiform area and the tibia-tarsal articulation, with a spongy fossula. The last structure was absent in specimens previously studied (Lent & Wygodzinsky 1979). Differences between this specimen and others previously described by several authors are discussed.

Influence of mating on ovarian follicle development in Triatoma infestans (Klug, 1834)

This works examines the influence of mating on ovarian follicle development in Triatoma infestans. The observations were carried out on both virgin and mated females, wich were killed at various times after their emergence. There was no difference in the ovarian development of both experimental groups during the first gonadotrofic cycle. By the 7th day mated females as well as virgn females showed vitellogenic oocytes. The coriogenesis and ovulation process began on the 13th day after imaginal moulting. However we could observe that egg-laying was dependent on mating. Mated females laid eggs whereas virgin females did not lay eggs. However ovarian production was significantly greater in the mated females. It is suggested that in T. infestans mating stimulates egg-laying but it does not influence the oogenesis and ovulation process