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PubMed2003

Fine structure of the salivary glands of Triatoma infestans (Hemiptera: Reduviidae).

The fine structure of the salivary glands of adult Triatoma infestans (Hemiptera: Reduviidae) bugs has been analyzed. Stereomicroscopy and scanning electron microscopy showed that each insect presents a pair of salivary glands, each pair containing three distinct units (main, supplementary, and accessory) with different sizes and colors. Transmission electron microscopy demonstrated that all gland units consist of a monolayer of epithelial cells surrounding a large central lumen. The gland units are enveloped by a thick basal lamina containing bundles of muscle cells. Microvilli are present at the apical plasma membrane domain of the gland cells, thus enlarging the available membrane area for saliva secretion towards the large gland lumen, although occasionally budding vesicles could be observed among the microvilli. Cytochemical analysis showed that the salivary gland cells of T. infestans present abundant endoplasmic reticulum profiles and several lipid droplets.

Animals↗
PubMed2001

Microsatellite isolation, linkage group identification and determination of recombination frequency in the peach-potato aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae).

Fifteen polymorphic microsatellite markers were used to establish linkage groups and relative rates of recombination in male and female Myzus persicae (Sulzer) (Hemiptera: Aphididae) (peach-potato aphid). We cloned nine markers from M. persicae and for these we report primer sequences and levels of allelic diversity and heterozygosity in four Australian M. persicae populations. Of the remaining six loci, four loci, also cloned from M. persicae, were obtained from G. Malarky (Natural History Museum, London) and two loci from Sitobion miscanthi were used. Additionally, the primer sequences of locus M77, a locus monomorphic in M. persicae but polymorphic in the closely related Myzus antirrhinii, are presented. Eleven of the 15 polymorphic markers were autosomal and four were X-linked. A linkage analysis was performed on a European pedigree of aphids containing five families with between seven and 11 offspring each. There was no linkage between any loci in females. In males, several pairwise comparisons yielded no recombinant offspring. With the exception of locus M40, these observations were supported in a linkage analysis performed on larger families produced from Australian M. persicae crosses. Locus M40 showed segregation consistent with involvement in a translocation between autosomes 1 and 3 in European samples but not in the Australian samples. From the Australian crosses we report an absence of recombination in males but high recombination rates in females. One X chromosome and four autosomal linkage groups were identified and tentatively assigned to chromosomes. The relevance of achiasmate meiosis to the evolution of sex is discussed.

Animals↗
PubMed2003

Karyotype variation in the South American aphid genus Neuquenaphis (Hemiptera, Aphididae, Neuquenaphidinae).

The endemic South American aphid genus Neuquenaphis (Hemiptera, Aphididae, Neuquenaphidinae) forms an important component of the phytophagous insect fauna associated with southern beeches, Nothofagus (Nothofagaceae), but has not previously been studied cytologically. As part of ongoing studies of the taxonomy, evolution and host relationships of this genus, the karyotypes of 12 species are described and illustrated. Species are mostly distinguishable by differences in number and/or relative lengths of chromosomes, with 2n (female) numbers ranging from 6 to 16. The taxonomic and evolutionary significance of the karyotype variation in this group are discussed.

Animals↗
PubMed2005

Triatoma dominicana sp. n. (Hemiptera: Reduviidae: Triatominae), and Trypanosoma antiquus sp. n. (Stercoraria: Trypanosomatidae), the first fossil evidence of a triatomine-trypanosomatid vector association.

Triatoma dominicana sp.n. (Hemiptera: Reduviidae: Triatominae) is described from a fifth instar nymph exuvia in Dominican amber and represents the first fossil representative of this subfamily. The new species is placed in the tribe Triatomini and tentatively in the genus Triatoma on the basis of the following characters; body length of 19.5 mm, body and appendages without long hairs, antenniferous tubercles without conspicuous apicolateral projections; abdomen with a series of five median tubercles; only fourth antennal segment annulated; lateral postocular callosities absent; stridulatory sulcus present and pronotum with discal and lateral tubercles. Trypanosoma antiquus sp. n. is described from two fecal droplets adjacent to Triatoma dominicana, thus providing the first fossil evidence of a triatomine-trypanosomatid vector association. The metatrypanosome stages of the fossil are similar in size to those of T. cruzi and could be a progenitor of this species. Mammalian hairs adjacent to the fecal droplets suggest that the vertebrate host for both the triatomine and trypanosomatid was a bat. Based on these findings, it is possible that bats were the original vertebrate hosts of T. cruzi-like trypanosomes.

Amber↗
PubMed2005

Movement, toxicity, and persistence of imidacloprid in seedling Tabasco pepper infested with Myzus persicae (Hemiptera: Aphididae).

Application of imidacloprid to the soil in which Tabasco pepper, Capsicum frutescens L., seedlings were growing was highly effective against the green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae). In just 48 h after the soil drench, aphid numbers on treated plants declined from 292.1 to 33.0 per plant, a reduction of 89%. By 72 and 96 h after the application, the reductions were 97 and 100%, respectively. Reductions in green peach aphid numbers also indicated that imidacloprid readily moved throughout the Tabasco pepper plant. Although, initial green peach aphid reductions at 24 and 48 h after imidacloprid application to soil, were greater on the lower leaves than on the upper leaves, by 72 h toxicity was high throughout the plant. At 48 h, overall green peach aphid reduction on seedlings grown in wet soil was significantly higher than that on plants growing in the drier soil. Regardless of soil moisture or leaf location, no live green peach aphids were detected on treated seedlings after 96 h. After the initial uptake period, toxicity to green peach aphid remained high for 5 wk. Under Tabasco pepper production conditions in Central America, the greatest need for aphid management is just after transplanting. Imidacloprid soil drenches before transplanting should offer the Tabasco pepper producer an extended period of aphid-free production.

Animals↗
PubMed1995

Type of rectal contents and infectivity of domiciliary populations of Triatoma infestans (Hemiptera: Reduviidae) in Argentina.

Different types of rectal content in domiciliary populations of Triatoma infestans (Hemiptera: Reduviidae: Triatominae) were associated with differences in the degree of infection with Trypanosoma (Schizotrypanum) cruzi. Field studies were carried out in a region of Argentina (Cordoba) where Chagas' disease is endemic. The rectal contents of domiciliary T. infestans were classified by color (clear, yellow, or brown) and the number of infective metacyclic stages of T. cruzi. The seasonal percentage of triatomines with metacyclics did not vary significantly, except in adults, in which it was greatest in spring (November-December). The mean density of T. cruzi per microliter of rectal material varied during the year, according to instar and color of the rectal contents. Clear recta had most metacyclics. December (late spring) may be more important for vectorial transmission of T. cruzi, because there are more infective adults (788) with higher counts of rectal metacyclics.

Age Factors↗
PubMed1999

Comparison of isoenzyme electrophoresis and morphometric analysis for phylogenetic reconstruction of the Rhodniini (Hemiptera: Reduviidae: Triatominae).

A phylogenetic reconstruction of the medically important tribe Rhodniini (Hemiptera: Reduviidae) based on multilocus isoenzyme electrophoresis is compared with phylogenetic patterns derived from a traditional morphometric analysis. Even with non-normality in the morphometric data, and some inequalities in population variances, discriminant analysis of size-free variables provided broadly similar phylogenetic information to that derived from isoenzyme analysis, revealing 3 main species groups within the genus Rhodnius.

Animals↗
PubMed2005

OS-D-like genes and their expression in aphids (Hemiptera: Aphididae).

It has been proposed that a family of small soluble binding proteins, variously named as chemosensory proteins, sensory appendage proteins, pherokines and OS-D-like proteins, are involved in insect chemoreception. These proteins are present in a wide range of insect species and have a characteristic four cysteine motif. We have cloned cDNAs and gene sequences encoding these proteins from a number of aphid species, the first report of such in the order Hemiptera and supporting the view that these genes predate the divergence of the Neoptera. In one aphid species, Megoura viciae, we have shown that the proteins are present primarily in adults with one protein being most abundant in antennae and legs. This supports the view that the proteins could be involved in chemoreception but our preliminary binding studies failed to detect binding to a range of compounds which are known to elicit an electrophysiological response by aphids.

Amino Acid Sequence↗
PubMed2006

Large-scale gene discovery in the pea aphid Acyrthosiphon pisum (Hemiptera).

Aphids are the leading pests in agricultural crops. A large-scale sequencing of 40,904 ESTs from the pea aphid Acyrthosiphon pisum was carried out to define a catalog of 12,082 unique transcripts. A strong AT bias was found, indicating a compositional shift between Drosophila melanogaster and A. pisum. An in silico profiling analysis characterized 135 transcripts specific to pea-aphid tissues (relating to bacteriocytes and parthenogenetic embryos). This project is the first to address the genetics of the Hemiptera and of a hemimetabolous insect.

Animals↗
PubMedDate not supplied

Embryology of Triatoma infestans (Klug), (Hemiptera, Reduviidae), a Chagas' disease vector.

This study reports the embryogenesis of T. infestans (Hemiptera, Reduviidae). Morphological parameters of growth sequences from oviposition until hatching (12-14 d 28 degrees C) were established. Five periods, as percent of time of development (TD), were characterized from oviposition until hatching. The most important morphological features were: 1) formation of blastoderm within 7% of TD; 2) germ band and gastrulation within 30% of TD; 3) nerve cord, limb budding, thoracic and abdominal segmentation and formation of body cavity within 50% of TD; 4) nervous system and blastokinesis end, and development of embryonic cuticle within 65% of TD; 5) differentiation of the mouth parts, fat body, and malpighian tubules during final stage and completion of embryo at day 12 to day 14 around hatching. These signals were chosen as appropriate morphological parameters which should enable the evaluation of embryologic modifications due to the action/s of different insecticides.

Animals↗
PubMedDate not supplied

[Triatoma delpontei Romaña & Abalos, 1947 (Hemiptera, Tratominae) in the Brazilian State of Rio Grande do Sul].

Triatoma delpontei (Romaña & Abalos, 1947) (Hemiptera, Triatominae) is an ornithophilic sylvatic with a particular association to the psittacid Myiopsitta monachus (Boaddert, 1783). It is found in the continental biogeographical province of the Chaco, where it inhabits the nests or M. monachus, in subtropical xerophytic forests. The authors report the first finding of T. delpontei in Brasil, in the "campanha" region of the State or Rio Grande do Sul (Barra do Quarai, Uruguaiana), on the right bank of the River Cuareim, not far from de Uruguayan border.

Animals↗
PubMedDate not supplied

Hemolymphatic components in vectors of Trypanosoma cruzi: study in several species of the subfamily Triatominae (Hemiptera: Reduviidae).

The members of the subfamily Triatominae (Hemiptera: Reduviidae) comprise a great number of species of medical importance in the transmission of the T. cruzi (American trypanosomiasis). The aim of this study was to contribute to the knowledge about the chemical composition in proteins, lipids, lipoproteins, and carbohydrates of vectors of Chagas' disease corresponding to twelve members of the subfamily Triatominae. This study was carried out in ninphs of the fifth instar and adult males of the species: T. delpontei, T. dimidiata, T. guasayana, T. infestans, T. mazzotti, T. pallidipennis, T. patagonica, T. platensis, T. rubrovaria, T. sordida of the Triatoma genus, and D. maximus and P. megistus of the Dipatalogaster and Panstrongylus genera respectively. The results show on one hand, qualitative differences in the protein composition, and on the other hand, similarity in the lipoprotein profiles. Lipids, proteins, and carbohydrates did not show significant differences between species or/and stages.

Animals↗
PubMedDate not supplied

[The influence of temperature on the biology of triatominae. IX. Rhodnius nasutus Stal, 1859 (Hemiptera, Reduviidae)].

The influence of temperature on the biology of Rhodnius nasutus Stal, 1859 (Hemiptera, Reduviidae) was studied in order to obtain a larger number of triatominae reared in laboratory to use in xenodiagnosis and to be able to get information for their proper control. The experiments were performed in two climatized chambers at 25 +/- 0.5 degrees C and 30 +/- 1 degrees C, 70 +/- 5% of relative humidity and photoperiod of 12 hours. Data in relation to evolution cycle, period between emergency of adults and first oviposition, fecundity, fertility, amount of blood ingested and fast resistance, are presented. The mean duration of the evolutive cycle for males and females was 145.7 days at 25 degrees C and 114.2 days at 30 degrees C. The mean of blood ingested to complete the evolutive cycle was 304.3 mg and 350.3 mg, at 25 degrees C and 30 degrees C, respectively. The triatominae survival on conditions of absolute fast was significantly higher at 25 degrees C than at 30 degrees C (P less than 0.01).

Analysis of Variance↗
PubMedDate not supplied

[Development of Rhodnius pictipes Stal, 1872 fed on mice and through a silicone membrane (Hemiptera, Reduviidae, Triatominae)].

Rhodnius pictipes (Hemiptera, Reduviidae) from Serra Norte, State of Pará, Brazil, acclimatized in an insectary at the Laboratório Nacional e Internacional de Referência em Taxonomia de Triatomíneos, Departamento de Entomologia, Instituto Oswaldo Cruz, were fed through a silicone membrane. In order to know the viability and the efficiency of this membrane compared with insects fed on mice, the number of bloodmeals taken, period of development of the five nymphal instars, longevity of adults, average amount of blood intake in each meal and percent of mortality were observed. A total of 310 insects, were used, comprising 50 nymphs of each instar, as well as 30 male and 30 female adults. Insects fed artificially had reduced minimal and maximal periods of development than the group fed on mice. The largest relative increase of body weight was observed in the 2nd instar followed by the 1st, and the amount of blood ingested increased during the development, to the 5th instar for both groups. There were no significant differences between the groups fed artificially and in vivo according to Tukey's test for p > 0.05. The percent of mortality in the 1st instar was 18% for artificially fed and 16% for the group fed on mice; these percentages decreased as insects developed until the 4th instar, without mortality, returning to increase in the 5th instar. R. pictipes was shown to be easily adaptable to artificial feeding, and could be considered as an important and viable experimental model.

Animals↗
PubMedDate not supplied

Nuclear rDNA-based molecular clock of the evolution of triatominae (Hemiptera: reduviidae), vectors of Chagas disease.

The evolutionary history and times of divergence of triatomine bug lineages are estimated from molecular clocks inferred from nucleotide sequences of the small subunit SSU (18S) and the second internal transcribed spacer (ITS-2) of the nuclear ribosomal DNA of these reduviids. The 18S rDNA molecular clock rate in Triatominae, and Prosorrhynchan Hemiptera in general, appears to be of 1.8% per 100 million years (my). The ITS-2 molecular clock rate in Triatominae is estimated to be around 0.4-1% per 1 my, indicating that ITS-2 evolves 23-55 times faster than 18S rDNA. Inferred chronological data about the evolution of Triatominae fit well with current hypotheses on their evolutionary histories, but suggest reconsideration of the current taxonomy of North American species complexes.

Animals↗
PubMed2001

Adult and nymphs of Microtriatoma trinidadensis (Lent, 1951) (Hemiptera: Reduviidae) caught from peridomestic environment in Bolivia.

This is the first report of adult and nymphs (20 nymphs of all stages and 4 adults) of Microtriatoma trinidadensis (Lent 1951) (Hemiptera: Reduviidae: Triatominae) collected in peridomestic environment, in the department of La Paz, Bolivia. These specimens were associated to Rhodnius stali Lent, Jurberg & Galvão 1993. The exceptional finding of M. trinidadensis in peridomestic environment, illustrates the general tendency of triatominae to adapt to human dwellings and dependences.

Animals↗
PubMed2004

Role of enhanced detoxication in a deltamethrin-resistant population of Triatoma infestans (Hemiptera, Reduviidae) from Argentina.

Deltamethrin and other pyrethroids have been extensively used in Argentina since 1980, for the chemical control of Triatoma infestans Klug (Hemiptera: Reduviidae). Recently, resistance to deltamethrin was detected in field populations by the survival of bugs exposed by topical application to the diagnostic dose estimated on the CIPEIN susceptible strain. Results of the current study showed low resistant ratios (RRs) to deltamethrin for the resistant populations (RR ranged from 2.0 for San Luis colony to 7.9 for Salta colony). Biochemical studies were made on the most resistant colony (Salta) and the susceptible strain (CIPEIN), in order to establish the importance of degradative mechanisms as a cause of the detected resistance. Esterase activity was measured on 3 days old first instars through phenylthioacetate and a-naphtyl acetate activities. The results showed a significant difference in no cholinesterase esterase activity from susceptible (7.6 +/- 0,7 micro M S./i.min.) and Salta resistant colony (9.5 +/- 0.8 microM S./i.min.). Cytochrome p450 mono-oxygenase (p450) activity was measured on individual insects through ethoxycoumarine deethylase (ECOD) activity using a fluorescence microplate reader. The dependence of ECOD activity on age and body region of the nymphs, and pH and time of incubation were studied in order to optimize the measurement. As a result, comparative studies were performed on abdomens of 2 days old first instars at pH 7.2 and 4 h incubation time. ECOD activity of first nymphs was significantly lower in the susceptible colony (61.3 +/- 9.08 pg ECOD/ insect) than in the resistant one (108.1+/- 5.7 pg ECOD/ insect). These results suggest that degradative esterases (no-cholinesterase) and mono-oxygenases cytochrome p450, play an important role in the resistance to deltamethrin in Salta colony from Argentina.

Animals↗