Incoordination, Paralysis and Recovery after Pyrethroid Treatment on Nymphs III of Triatoma infestans (Hemiptera: Reduviidae)

Symptoms of poisoning for deltamethrin and cis-permethrin on nymphs III of Triatoma infestans were described. The time required for incoordination and paralysis were determined. Deltamethrin was equal or more rapid in the onset of the first effect (accordingly to dose), and cis-permethrin in the onset of the second one. There were no significant differences between incoordination doses 50% (IncD50s) at different times for the two pyrethroids. They showed equivalent incoordination power, but the nymphs treated with deltamethrin recovered slightly more rapid and in greater amount than the nymphs treated with cis-permethrin. The recovery was inhibited by the simultaneus application of piperonyl butoxide. This result suggests that biotransformation by mixed-function microsomal oxidases are involved in the process of recovery

Isoenzymes Detect Variation in Populations of Triatoma brasiliensis (Hemiptera: Reduviidae: Triatominae)

Triatoma brasiliensis is one of the most important vectors of Chagas disease in the semiarid zone of the northeast of Brazil. Intraspecific morphological and behavioural variation has been reported for different populations. Results for four distinct populations using eight isoenzymes are reported here. The literature describes three subspecies: T. brasiliensis brasiliensis Neiva, 1911; T. brasiliensis melanica Neiva & Lent, 1941 and T. brasiliensis macromelasoma Galvão, 1956. These subspecies differ mainly in their cuticle colour pattern and were regarded as synonyms by Lent and Wygodzinsky (1979). In order to evaluate whether the chromatic pattern is a morphological variation of different melanic forms within T. brasiliensis or due to interspecific variation, field collections were performed in localities where these three subspecies have been described: Caicó (Rio Grande do Norte), the type-locality for T. b. brasiliensis; Petrolina (Pernambuco) for T. b. macromelasoma and Espinosa (Minas Gerais) for T. b. melanica. A fourth distinct chromatic pattern was found in Juazeiro (Bahia). A total of nine loci were studied. Values of Nei's genetic distance (D) were calculated. T. b. brasiliensis and T. b. macromelasoma are the closest populations with a D=0.295. T. b. melanica had a D ³ 0.537 when compared to the others, a distance in the range of interspecific variation for other triatomine species

Morphological Studies on the Triatoma brasiliensis Neiva, 1911 (Hemiptera, Reduviidae, Triatominae) Genital Structures and Eggs of Different Chromatic Forms

Triatoma brasiliensis is considered one of the most important Chagas disease vectors being a widespread species in semiarid areas of northeastern Brazil. The species displays distinct chromatic patterns of the cuticle in different localities. Four populations were analyzed in this study: 1-Caicó, Rio Grande do Norte, it will be called the brasiliensis population; 2-Espinosa, Minas Gerais, the melanica population; 3-Petrolina, Pernambuco, the macromelasoma population, and 4-Juazeiro, Bahia, the darker one in overall cuticle coloration, the Juazeiro population. In order to differentiate the four populations of T. brasiliensis, a comparative morphological analysis of external genital structures and of eggs were carried out. The analysis of the male genital structures evidenced minor individual structural variations that did not correlate with chromatic differences or the geographical origins, emphasizing the importance of examining sufficiently large and representative samples before using minor genital variations for taxonomic diagnosis. By scanning electron microscopy of the egg exochorion, each chromatic population presented a distinct ornamentation pattern. The melanica population differed mainly from the other populations studied since it had about 40.6%, 69.6% and 76.6% more perforations, on each cell exochorion, than the brasiliensis, the Juazeiro and the macromelasoma populations respectively. In the melanica population the perforation layout is also peculiar, with densely distributed perforations over all the egg surface. Morphometric measures of the eggs showed statistically significant differences: the macromelasoma population presented the longest length (2.43 mm) while the shortest was recorded in the brasiliensis population (2.29 mm).

Estudo morfológico de Triatoma guazu Lent & Wygodzinsky, 1979 (Hemiptera, Reduviidae, Triatominae)

A female of Triatoma guazu Lent & Wygodzinsky, 1979, a rare species from which the allotype was recently described, was studied by scanning electronic microscopy and videomicroscope. Some structures of the head and the thorax are shown. Some of them could have taxonomic importance, as the oculo-ocellar region, the buccula, the anterolateral angle of the collar, the scutellum, wings and the stridulatory sulcus, which has an unusual lateral high rim

Desenvolvimento de Rhodnius pictipes Stal, 1872 alimentado através de membrana de silicone e em camundongos (Hemiptera, Reduviidae, Triatominae)

Rhodnius pictipes (Hemiptera, Reduviidae) from Serra Norte, State of Pará, Brazil, aclimatized 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.

Ecotopes, Natural Infection and Trophic Resources of Triatoma brasiliensis (Hemiptera, Reduviidae, Triatominae)

Triatoma brasiliensis is considered as one of the most important Chagas disease vectors in the northeastern Brazil. This species presents chromatic variations which led to descriptions of subspecies, synonymized by Lent and Wygodzinsky (1979). In order to broaden bionomic knowledge of these distinct colour patterns of T. brasiliensis, captures were performed at different sites, where the chromatic patterns were described: Caicó, Rio Grande do Norte (T. brasiliensis brasiliensis Neiva, 1911), it will be called the "brasiliensis population"; Espinosa, Minas Gerais (T. brasiliensis melanica Neiva & Lent 1941), the "melanica population" and Petrolina, Pernambuco (T. brasiliensis macromelasoma, Galvão 1956), the "macromelasoma population". A fourth chromatic pattern was collected in Juazeiro, Bahia the darker one in overall cuticle coloration, the "Juazeiro population". At the sites of Caicó, Petrolina and Juazeiro, specimens were captured in peridomiciliar ecotopes and in wilderness. In Espinosa the specimens were collected only in wilderness, even though several exhaustive captures have been performed in peridomicile at different sites of this municipality. A total of 298 specimens were captured. The average registered infection rate was 15% for "brasiliensis population" and of 6.6% for "melanica population". Specimens of "macromelasoma" and of "Juazeiro populations" did not present natural infection. Concerning trophic resources, evaluated by the precipitin test, feeding eclecticism for the different colour patterns studied was observed, with dominance of goat blood in household surroundings as well as in wilderness

Distribuição Geográfica e Dispersão Alti-latitudinal de Alguns Gêneros e Espécies da Tribo Triatomini Jeannel, 1919 (Hemiptera, Reduviidae, Triatominae)

Geographical Distribution and Alti-latitudinal Dispersion of Some Genera and Species of the Tribe Triatomini Jeannel, 1919 (Hemiptera, Reduviidae, Triatominae) - With the currently known distribution of genera and species of the tribe Triatomini Jeannel, 1919, maps and diagrams were prepared, showing the geographical area occupied by the species and their respective dispersion in grades of latitude and altitude. Two genera are not treated: Panstrongylus Berg, 1879, already published and Triatoma Laporte, 1832, that is being published partially in several articles. Genus Eratyrus Stal, 1859, has two species, while Dipetalogaster Usinger, 1939, Mepraia Mazza, Gajardo & Joerg, 1940, Paratriatoma Barber, 1938 and recently created genus Hermanlentia Jurberg & Galvão, 1997, have only one each. The study of these maps and diagrams permits a better knowledge about some ecological requirements of Chagas' disease vectors and detects gaps in the geographical distribution, where the species were not found but probably they could be prevalent

Metabolic Post-feeding Changes in Fat Body and Hemolymph of Dipetalogaster maximus (Hemiptera:Reduviidae)

Lipids and glycogen in fat body as well as the modifications in the wet weight of this organ were evaluated in an unfed insect, Dipetalogaster maximus, on day 5 after adult ecdysis (time 0) and during a 30-day period after ingestion of blood meal. Total lipids, high density lipophorin (HDLp), carbohydrates, total proteins and uric acid were determined in the hemolymph during the same period. Fat body wet weight was maximum on day 10 post-feeding and represented on day 30 only 42% of the maximum weight. Lipids stored in the fat body increased up to day 15 reaching 24% of the total weight of tissue. Glycogen was maximum on day 20, representing approximately 3% of the fat body weight. HDLp represented at all times between 17-24% of the total proteins, whose levels ranged between 35 and 47 mg/ml. Uric acid showed at 20, 25 and 30 days similar levels and significantly higher than the ones shown at days 10 and 15. Hemolymphatic lipids fluctuated during starvation between 3-4.4 mg/ml and carbohydrates showed a maximum on day 15 after a blood meal, decreasing up to 0.26 mg/ml on day 25. The above results suggest that during physiological events such as starvation, the availability of nutrients is affected, involving principally the fat body reserves

Vital Statistics of Panstrongylus geniculatus (Latreille 1811) (Hemiptera: Reduviidae) under Experimental Conditions

A statistical evaluation of the population dynamics of Panstrongylus geniculatus is based on a cohort experiment conducted under controlled laboratory conditions. Animals were fed on hen every 15 days. Egg incubation took 21 days; mean duration of 1st, 2nd, 3rd, 4th, and 5th instar nymphs was 25, 30, 58, 62, and 67 days, respectively; mean nymphal development time was 39 weeks and adult longevity was 72 weeks. Females reproduced during 30 weeks, producing an average of 61.6 eggs for female on its lifetime; the average number of eggs/female/week was 2.1. Total number of eggs produced by the cohort was 1379. Average hatch for the cohort was 88.9%; it was not affected by age of the mother. Age specific survival and reproduction tables were constructed. The following population parameters were evaluated, generation time was 36.1 weeks; net reproduction rate was 89.4; intrinsic rate of natural increase was 0.125; instantaneous birth and death rates were 0.163 and 0.039 respectively; finite rate of increase was 1.13; total reproductive value was 1196 and stable age distribution was 31.2% eggs, 64.7% nymphs and 4.1% adults. Finally the population characteristics of P. geniculatus lead to the conclusion that this species is a K strategist.

Population Biology of Rhodnius domesticus Neiva & Pinto, 1923 (Hemiptera: Reduviidae) under Laboratory Conditions

The entire life cycle of Rhodnius domesticus, fed weekly on mice, was studied under controlled conditions. Aspects related to hatching, life time, mortality, feeding behaviour and fecundity for each stage of the insect life-cycle were evaluated. The hatching rate observed in 100 eggs was 57% and the mean time of hatching was 15.6 days. Forty-six nymphs (80.7%) completed the cycle and the mean time from NI to adult was 93.8 days. The average span in days for each stage was 12.4 for NI, 9.8 for NII, 14.2 for NIII, 16.8 for NIV and 25.0 for NV. The number of bloodmeals in each nymphal stage varied from 1 to 3. The mortality rate was 12.3% for NI, 3.5% for NII and 1.7% for NIII and NV nymphs. The mean number of eggs laid per female in a 9-month period was 333.1. Average adult survival rates were 287.6 +133 and 328 +73 days for males and females respectively.

Triatoma jurbergi sp. n. do Norte do Estado do Mato Grosso, Brasil (Hemiptera, Reduviidae, Triatominae) com uma Atualização das Sinonímias e outros Táxons

Triatoma jurbergi n. sp. is described based on nine specimens of both sexes deposited in the Rodolfo Carcavallo Collection in the Oswaldo Cruz Institute Entomological Collection. The new species can be separated from the closely related Triatoma guazu Lent & Wygodzinsky, 1979 by several characters. The most important are longer anteocular region; thin and pointed juga; the shape of the eyes without concavity in the posterior edge; much longer second rostral segment, passing the posterior edge of eye; the absence of a ventral longitudinal depression on the abdomen; the general color redish, brown and orange and the male genitalia, mainly in the vesica lightly chitinized and smaller, the phallosome with apical projection and the pointed apex of the endosome process.

Life Cycle and Reproductive Patterns of Triatoma rubrofasciata (De Geer, 1773) (Hemiptera: Reduviidae), under Laboratory Conditions

The life cycle and reproductive patterns of Triatoma rubrofasciata were studied along with laboratory conditions for the establishment of a prolific colony. The insects were divided into four groups: two of them were maintained at room temperature (20.5°C to 33°C and 85% ± 5% of relative humidity), the other two in a climatic chamber (CC) (temperature: 29°C, humidity: 80% ± 5%). The groups were fed weekly or fortnightly on Swiss mice. The females from the group kept in the CC and fed weekly had longer life span, as well as a higher number of eggs, fertile eggs and hatchings; the group kept in the CC and fed fortnightly had a shorter life span for the 1st, 2nd and 3rd instars and a lower mortality rate for all instars. It was concluded that a constant high temperature (CC at 29°C) is the most suitable condition for the maintenance of a colony of T. rubrofasciata regardless of the interval between repasts.

Resistance to Starvation of Triatoma rubrofasciata (De Geer, 1773) under Laboratory Conditions (Hemiptera: Reduviidae: Triatominae)

The present work aims at learning the period of resistance to starvation (molting/death) of Triatoma rubrofasciata in different stages of development and the respective loss of weight until death. Eggs of specimens from the greater area of the city of São Luis in the State of Maranhão, Brazil, yielded approximately 300 nymphs. These nymphs were placed in labelled Borrel glasses, in which they were weekly fed on rats (Rattus norvegicus), until reaching the stage to be observed. The experiments were conducted in a climatic chamber regulated at 29 ± 1° C, 70% relative humidity and 12 hr photoperiod. The resistance to starvation increased according to the stage of development, except for adult bugs, whose results were similar to the 3rd stage nymphs. In all these development stages there was an abrupt loss of weight in the first week, followed by a gradual loss until death. Comparing this work with those of other authors, it was observed that T. rubrofasciata is among the less resistant triatomine species.