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At least 217 records · Page 12Linked to original sources

Influence of the blood meal source on the development of Triatoma infestans, Triatoma brasiliensis, Triatoma sordida, and Triatoma pseudomaculata (Heteroptera, Reduviidae).

The objective of this study was to determine the influence of the blood meal source on the life cycle and reproductive development of female Triatoma infestans (Klug, 1834), Triatoma brasiliensis Neiva, 1911, Triatoma sordida (Stal, 1859), and Triatoma pseudomaculata Corrga & Espfinola, 1964. In all triatomine species studied the life cycle was shorter for the groups fed on mice than for those fed on pigeons, the range of differences being between 1.5 times (T pseudomaculata and T. infestans) and 2.4 times (T brasiliensis). The mortality rate of nymphs during the life cycle tended to be greater in insects fed on pigeons than in those fed on mice, the differences for T. brasiliensis being statistically significant. Females of T sordida and T pseudomaculata had a greater fecundity than those of T. infestans and T. brasiliensis independently of the blood meal source. The differences of fecundity observed probably reflect differences in the availability of blood in the silvatic ecotopes of these species, meals being more frequent for T. infestans and T brasiliensis, which live at high densities in association with rodents in highly stable ecotopes. Because T. sordida and T. pseudomaculata live in more unstable ecotopes with fewer sources of blood they form small sparse colonies and invest more energy in reproduction than maintenance.

Animal Feed↗

Field ecology of sylvatic Rhodnius populations (Heteroptera, Triatominae): risk factors for palm tree infestation in western Ecuador.

Most Rhodnius species (Triatominae) are primarily associated with palm trees. They maintain enzootic Trypanosoma cruzi transmission and are responsible for human infection (causing Chagas disease) through the Neotropics. Assessing whether individual palm traits (ecological and/or botanical) may increase the risk of palm infestation by triatomines is relevant in areas where bugs invade houses flying from peridomestic palms. We developed a novel fieldwork approach with that objective, and applied it to study infestation by sylvatic Rhodnius ecuadoriensis in 110 tagua palms (Phytelephas aequatorialis). Palm infestation (23% overall) was non-randomly distributed in our sample. Palms located in anthropic landscapes were frequently infested (>27%, n=92), whereas no bugs were collected from palms surveyed within forest remnants (n=18; P=0.01). The presence of abundant decaying vegetable matter (P=0.001) and (to a lesser extent) epiphytic plants (P=0.049) on palm crowns and stems increased the probability of infestation and was positively correlated with the apparent density of bug colonies (R2=0.68). A trend towards higher infestation rates in male palms (34% vs. 18%) could relate to female palm management (removal of infrutescences and vegetable debris) in areas where palm seeds are harvested. An outline of 'risk palm ecotopes' and environmental management-based strategies for the control of peridomestic, palm tree-living vector populations are proposed.

Animals↗

Ventilatory structures in Cryphocricos barozzii Signoret (Heteroptera, Naucoroidea).

Plastron and spiracular features strongly resemble those of Aphelocheirus aestivalis (Fab.), described by Messner et al. (1981). Plastronal foliose hairs, somewhat irregular shaped are regularly distributed in the plastron. Very numerous tiny openigs on sternites an tergites connect platronal air with a subcuticular air film limited internally apparently by a membrane. Aplicated, radial, structure at the proximal end of the tracheae, almost occluding the extremely fine spiracular openings, appear with lesser variations in both species, suggesting close relationships than accepted until now.

Journal Article↗

[The cimicids and their importance in public health (Hemiptera-Heteroptera; Cimicidae)].

A review of the Cimicidae of importance in public health is presented. After a general morphological study, special attention is given to knowledge of the biology and ecology of bed-bugs, mainly as regards their relation to the human environment and the possibility of their role in disease transmission. The species Cimex lectularius and C. hemipterus are given particular attention and data on their relevance to questions of public health are revised. Taxonomy, biosystematic and geographical distribution are presented, the epidemiologically important groups listed and control measures discussed. The paper ends with identification keys for both adult and immature stages as well as for arthropod indoor fecal traces.

Animals↗

[Anatomic and histologic studies of a Triatominae subfamily (Heteroptera, Reduviidae). Triatoma infestans' brain and its nerves].

To give a concrete aspect of structure, topography and function of the different nervous systems of the Triatominae, we begin this study with a description of the senso-motor system. As the first part we choose the study of the brain and its nerves. The external form of the brain is conditioned by the anatomy and morphology of the head. The brain is situated in the posterior part of the head beneath and behind the ocelli. It is characterized by the reduction of its longitudinal extension and, by this, the connectives between Syncerebrum and Gnathocerebrum are extremely short, but large, and the third commissure is included in the mass of the mandibular segment of the Gnatocerebrum. The optical masses are of the typical form, also the optical commissure. The Central Corps is volumous and is directly linked with the majority of the centres of the Protocerebrum and Deutocerebrum. The Pedunculated Corps has only one glomerulus that looks like a pedunculated mushroom without any signal of the formation of a calyx, found in ants and other more evoluted insects. Beneath the Central Corps, the extremities of the pedunculus disintegrate and form a number of claviform annexes like in the primitive Machilidae. The Deutocerebrum is characterized by volumous antennal centre, composed by numerous little glomeruli in peripheral situation. The Tritocerebrum is very reduced and has in its anterior part two very short frontal connectives and, by this, the frontal ganglion lies near the Tritocerebrum. The compact mass of the Gnathocerebrum shows its composition by three pairs of ganglions only by observation of series of preparations. With exception of the Lobi optici, 8 pair nerves and 3 impair nerves come from the brain: From the Protocerebrum: the nerves of the ocelli and the nerve of the Corpus allatum. From the Deutocerebrum: the nerves of the antennae and those of the pharynx. From the Tritocerebrum, the nerves of the labrum and, by the frontal ganglion, the Nervus recurrens and the nerve of pharyngeal muscles. From the Gnathocerebrum: the nerves of the amndibulae, maxillae, labium and of the salivary glands.

Animals↗

Natural lectin activity in the haemolymph of Panstrongylus megistus (Heteroptera: Reduviidae).

The haemolymph of Panstrongylus megistus showed a natural lectin activity for a wide range of vertebrate erythrocytes. Agglutination was observed against all vertebrate erythrocytes tested (human ABO, duck, rabbit, mouse, sheep, chicken and cow). Cow erythrocytes showed the lowest titre. Concerning human erythrocytes, the lectin activity was similar in the types A+, B+ and AB+ while the highest activity was observed in the type O+. Determination of minimal inhibitory concentrations was carried out with human erythrocytes type O+. Agglutination was inhibited by several carbohydrates (rhamnose, D-galactose, raffinose, D-lactose and D-fucose). Rhamnose was reported as the strongest inhibitor (0.78 mM). The results suggest the presence of more than one lectin in the haemolymph of P. megistus.

Agglutination Tests↗

Comparative meiotic studies in Triatoma sordida (Stål) and T. guasayana Wygodzinsky & Abalos (Reduviidae, Heteroptera).

Triatoma sordida and T. guasayana are competent Trypanosoma cruzi vectors, with overlapping distribution areas in Argentina. Both species are morphologically similar, and their immature stages are hard to discriminate. Cytogenetic studies in the genus Triatoma reveal scarce karyotypic variations, being 2n = 20 + XY the most frequent diploid number in males. In the present work the meiotic behaviour of different Argentinian populations of T. sordida and T. guasayana has been analyzed; the meiotic karyotype of both species has also been compared. The species differ in total chromosome area and in the relative area of the sex chromosomes. These meiotic karyotypic differences constitute an additional tool for the taxonomic characterization of T. sordida and T. guasayana. The analysis of an interpopulation hybrid of T. sordida (Brazil x Argentina) reveals a regular meiotic behaviour; despite the presence of heteromorphic bivalents. Our observations support the hypothesis that karyotype variations through the gain or loss of heterochromatin can not be considered as a primary mechanism of reproductive isolation in Triatoma.

Animals↗

The postembryonic development of the ocellar system of Triatoma infestans Klug (Heteroptera: Reduviidae).

Simple eyes or ocelli coexist with compound eyes in many adult insects. The change in the morphology of the ocelli along the five larval instars of Triatoma infestans was studied by light and scanning electron microscopy. Our analysis showed that the development of the ocelli of these bugs occurs gradually along the larval life. The photoreceptor layer is present from the second-instar onwards. The cornea appears first at the imaginal stage and grows up to the 18-20th day after the last ecdysis, associated to an increase in the retinal mass. Findings are discussed in a comparative fashion and in relation to the functionality of the ocellar system in T. infestans.

Animals↗

Rhodnius amazonicus Almeida, Santos & Sposina, 1973, bona species, close to R. pictipes Stål, 1872 (Heteroptera, Reduviidae, Triatominae).

The discovery of two atypical specimens of Rhodnius pictipes Stål, 1872 in French Guiana and the examination of the female holotype of R. amazonicus Almeida, Santos & Sposina, 1973, the only specimen of this species so far known, lead us to propose the rehabilitation of R. amazonicus synonymized with R. pictipes. The male is described for the first time and the female redescribed. Both external characters and genitalia distinguish R. amazonicus from R. pictipes. R. amazonicus shows affinities not only with pictipes but also with R. stali Lent, Jurberg & Galvão, 1993 and R. paraensis Sherlock, Guitton & Miles, 1977. A key is provided for these four species forming, in all likelihood, a natural group, i.e. the "pictipes group".

Animals↗

Biology of Triatoma klugi Carcavallo, Jurberg, Lent & Galvão 2001 (Heteroptera: Reduviidae) under laboratory conditions: effects of distinct blood sources and susceptibility to Trypanosoma cruzi and Trypanosoma rangeli.

The life cycle of Triatoma klugi Carcavallo, Jurberg, Lent & Galvão 2001 was compared under laboratory conditions using two groups of the F1 generation obtained from field-collected bugs. Among the 100 nymphs weekly fed on mice (Group A) or chicken (Group B), 77% of Group A and 67% of Group B reached the adult stage, and the mean time from the first nymphal stage to adult was 190.08 +/- 28.31 days and 221.23 +/- 40.50, respectively. The average span in days for each stage per group and the number of blood meals required for each stage were also evaluated. The overall mortality rate was 23% and 33% for Groups A and B, respectively. The mean number of eggs laid per month in a three-month period was of 56.20, 51.70 and 73.20 for Group A, and 64.50, 53.50 and 38.71 for Group B. Despite the blood source, comparative analysis revealed no statistically significant differences in the life cycle of T. klugi under laboratory conditions. Infection rates over 60% were observed for both Trypanosoma cruzi strains tested. Even revealing high infection rates of the hemolymph by T. rangeli strains, T. klugi revealed no salivary gland infections and was not able to transmit the parasite.

Animals↗

Aggregation mediated by faeces and footprints in Triatoma pseudomaculata (Heteroptera: Reduviidae), a Chagas disease vector.

The behavioural response of Triatoma pseudomaculata to chemical substances present in their faeces or cuticle (footprints) was analyzed. Groups of larvae were simultaneously exposed to a clean filter paper and to another paper impregnated with a chemical stimulus in a circular arena. In these choice experiments, the insects aggregated significantly around papers impregnated with dry faeces. In addition, the bugs also showed a significant aggregation response to papers impregnated with compounds derived from their cuticle that were deposited by contact on the substrate. These results indicate that chemical compounds that affect the behaviour of T. pseudomaculata are present in the faeces and in the cuticle of this species. Results are discussed in relation to chemical communication in the Triatominae, as well as to the potential use of these substances in traps or sensors for the detection of this species.

Animal Communication↗

Crossing experiments detect genetic incompatibility among populations of Triatoma brasiliensis Neiva, 1911 (Heteroptera, Reduviidae, Triatominae).

Triatoma brasiliensis is composed of at least four geographic populations (brasiliensis, melanica, macromelasoma, and juazeiro) that have distinct chromatic, morphologic, biologic and ecologic patterns, and genetic composition. Reciprocal crosses between all pairwise combinations were carried out in order to evaluate the genetic and reproductive compatibility of these four populations. The F1 individuals developed normally and the resulting adults were crossed again to test the F2 and F3 viability. Genetic incompatibility was found between melanica and brasiliensis populations.

Animals↗