Survival and molting incidence after heat and cold shocks in Panstrongylus megistus Burmeister.

Survival and molting incidence were studied after heat (40 degrees C) and cold (0 degree C) shocks in specimens of Panstrongylus megistus with the aim of establishing its response to temperature stress under laboratory rearing conditions and to understand occasional changes in the biological characteristics of specimens captured in nature. The response to the thermal shocks was found to vary as a function of the temperature and duration of the shock, developmental phase and sex of the specimens, and in certain cases, the insect habit and nourishment conditions. P. megistus specimens were found to be less resistant to the heat shock assay than Triatoma infestans, another reduviid species. The short cold shock affected survival of P. megistus more than did the heat shock, survival of fully-nourished specimens being preferential. The response of adults to the short cold shock was affected by sex, males being generally less resistant. The insect sylvatic habit was found to seldom affect the thermal shock response established for specimens with domestic habit. A decrease in molting frequency and sometimes a slowdown of the molting rate were found after the short heat and cold shocks, possibly promoted by change in hormonal balance, and differing from patterns reported for T. infestans. The results indicate that no generalization should be made for different reduviid species in terms of the effects of temperature shocks.

[Triatoma brasiliensis Neiva, 1911 (Hemiptera, Reduviidae): observations on dynamics of feeding behavior in an artificial ecotope]. / Triatoma brasiliensis (Neiva,1911) (Hemiptera, Reduviidae): observações sobre seu comportamento em relação fonte alimentar em galinheiro experimental.

In order to study the behavior of triatomine bugs under artificial ecotopic conditions, an experimental, double-walled poultry coop was built. Its inside walls were made of sun-dried clay blocks which could be broken apart for better access to the insects hiding in their crevices. The coop was subdivided into two main areas of different sizes using wire netting and a wall made of perforated bricks. The chickens, the only food source available for the triatomines, were kept in the larger, rectangular area, further subdivided diagonally. The triatomines were released in the smaller area and were allowed to migrate to the larger one though the holes in the bricks. Information about migration, survival, and hiding places of fourth-stage nymphs of Triatoma brasiliensis was thus gathered. At 30-day intervals, over a period of six months, the inner walls of the house were taken apart and inspected. The nymphs were marked with different colors according to the month and place of capture. It was found that 88.5% of the nymphs were captured near the roost and found engorged. After having taken their first blood meal, they would remain in the vicinity of their food source. The results obtained are considered epidemiologically relevant, and particularly so as pertaining to the control of the vectors of Chagas disease.

[Survival and occurrence of molting in Triatoma infestans Klug (Hemiptera, Reduviidae) after temperature shock]. / Sobrevivência e ocorrência de muda em Triatoma infestans Klug (Hemiptera, Reduviidae) após choque de temperatura.

Survival and molting occurrence were studied in specimens of Triatoma infestans over 30 days after temperature shocks. Hyperthermal and hypothermal shocks could be found to affect both survival and molting incidence as a function of temperature and period of the development phase and sex of the specimens. Considering the various test conditions, the shock at 0 degree C for 12 h was found to elicit the most deleterious effect, whereas shocks at 40 degrees C and 0 degree C even for 1 h are interpreted as affecting the hormonal balance which controls molting. Cases of a rise in post-shock survival are suggested to have been favored by heat-shock protein action.

[Epidemiologic study of the sources of blood feeding of the triatominae of the Aroeira farm (Catolé do Rocha, Paraìba) and neighboring localities]. / Estudo epidemiológico de fontes de alimentação sangüínea dos triatomíneos da Fazenda Aroeira (Catolé do Rocha, Paraíba) e circunvizinhanças.

We have analysed the blood feeding sources of 94 triatomine bugs (51 T. brasiliensis, 42 T. pseudomaculata and one R. neglectus) from Fazenda Aroeira, in Catolé do Rocha Municipality, Paraíba State, and four neighbouring localities. The positivity for marsupial, man and bird blood were, respectively, 39.7, 6.2 and 23.0%. Three insects from Fazenda Aroeira were positive both for T. cruzi and marsupial blood while only one of the three was positive for another mammal. Marsupials are the most important source of T. cruzi for the insects of the area, which have little contact with man.

Distribuiçäo e índice de infecçäo natural de triatomíneos capturados na regiäo de Campinas, Säo Paulo, Brasil / Distribution and index of natural infection of Triatominae captured in the region of Campinas, Säo Paulo, Brazil

Entre 1974 e 1981 em 53 municípios pertencentes à regiäo administrativa de Campinas, SP, foram coletados pela SUCEN e encaminhados ao laboratório de Mogi-Guaçu, 36.406 triatomíneos, dos quais foram examinados 33.131 exemplares; destes, foram observados 3.176 (9,60%) infectados pelo T. cruzi. No referente ao local de captura, constatou-se que 4.516 (12,40%), foram encontrados nas casas, sendo 1.827 (40,46%) habitantes e a grande maioria, 30.460 exemplares (83,67%) coletados em anexos de diferentes tipos e os 1.429 (3,92%) restantes em focos silvestres. A espécie predominante foi o P. megistus, com 33.263 exemplares capturados e também aquela de maior índice de infecçäo pelo T. cruzi (10,26%)

Number of chromosomes, Feulgen-DNA content, and nuclear phenotypes in domestic and wild specimens of Panstrongylus megistus.

Specimens of Panstrongylus megistus with different levels of adaptation to a domestic way of life had some of their nuclear and chromosomal characteristics compared, in an attempt to differentiate them by cytological means. The number of chromosomes in male testes was found not to differ. The nuclear frequency and phenotypes of the Malpighian tubules were also found to be the same. On the other hand, Feulgen-DNA values of metaphase chromosomes in insects from a population with a sylvatic distribution were found to be larger than those in specimens from a domestic population. The differences in Feulgen-DNA values, however, may not represent real differences in DNA content, but may possibly be due to differences in DNA-protein complexes.

Trypanosoma (Megatrypanum) rochasilvai, sp. n., encontrada no Estado de Sao Paulo, Brasil, parasitando o Orzomys laticeps (Leche, 1886) (Rodentia-Cricetidae). / Trypanosoma (Megatrypanum) rochasilvai, sp. n., found in the State of Sao Paulo, Brazil parasiting Oryzomys laticeps (Leche, 1886) (Rodentia-Cricetidae)

Ao examinar roedores silvestres capturados nas matas da Fazenda Sete Lagoas, no municipio de Moji-Guacu, SP, constatamos a presenca de tripanossomos do subgenero Megatrypanum no sangue de 2 exemplares de Oryzomys laticeps (Leche, 1886) o que possibilitou a realizacao de estudos biometricos, bem como tentativas de inoculacao em animais de laboratorio, cultivo "invitro", xenodiagnostico e cortes histologicos.A discussao taxonomica comparada com os Trypanosoma (Megatrypanum) conhecidos, parasitas de roedores, permitiu-nos considera-la como sendo uma especie, denominada Trypanosoma (Megatrypanum) rochasilvai n.sp