Nathalie Costa da Cunha

Artificial feeding of Amblyomma cajennense (Acari: Ixodidae) fasting females through capillary tube technique

O presente trabalho teve como objetivos adaptar a tecnica de alimentacao artificial por meio de tubos capilares para femeas de Amblyomma cajennense e verificar a sua influencia sobre os parâmetros biologicos da especie. Femeas em jejum por 45 dias foram alimentadas com sangue bovino citratado usando tubos capilares por diferentes periodos de tempo: 12, 24 e 48 horas, 2 horas/dia e 6 horas/dia por 8 dias consecutivos, sendo que cada grupo foi composto por 20 carrapatos. Em seguida, os carrapatos foram expostos a coelhos para completar a alimentacao e seus parâmetros biologicos foram analisados. Apos alimentacao artificial, os carrapatos apresentaram idiossoma arredondado mesmo a vista desarmada. Os grupos 24 horas, 8 dias/2 horas/dia e 8 dias/6 horas/dia tiveram maior ganho de peso, nao havendo diferenca estatistica entre eles. Desta forma, nas condicoes do presente trabalho, 24 horas de alimentacao artificial foram suficientes para que femeas em jejum aumentassem seu peso em 2,43mg. A alimentacao artificial utilizando tubos capilares nao interferiu nos parâmetros relativos as fases parasitaria e nao-parasitaria de femeas A. cajennense.The present study aimed to adjust the artificial feeding technique through capillaries and to verify its influence over the biology of Amblyomma cajennense females. Five groups of 20 female ticks were formed. Females were starved for 45 days and then fed with citrated bovine blood using capillary tubes in different periods of time. Females were divided in five experimental groups with 20 individuals each and fed as follows: groups uninterruptedly fed for 12, 24, and 48 hours and groups fed 2 and 6 h a day, for a period of 8 days. Subsequently, ticks were exposed to rabbits for complementary feeding and their biological parameters were analyzed. TIcks were capable of feeding, showing rounded idiosoma, visible even to naked eyes, following the feeding period. The groups fed for 24 hours, 2 hours/day for eight consecutive days or 6h/day for eight consecutive days presented greater weight gain, without statistically significant differences. These results suggested that 24 hours of artificial feeding were enough for fasting females to increase weight by 2.43 mg. Artificial feeding through capillaries did not interfere with parasitic and non-parasitic phases of A. cajennense females.

Alterações nos parâmetros hematológicos de Gallus gallus domesticus experimentalmente infectados por Borrelia anserina

Avian spirochaetosis is a cosmopolite acute septicemic disease of many avian species, caused by Borrelia anserina Sakharoff, 1891. The present study assesses the estimate of the hematological alterations of Gallus gallus domesticus experimentally infected with B. anserina by vector Argas (Persicargas) miniatus. Twenty-seven fowls of the species G. g. domesticus, 67 days old, were randomly allocated into three groups composed by nine animals each. One group was exposed to B. anserina infected ticks (Group 1), other one to ticks free of this agent (Group 2), and another group not exposed to ticks (Group 3). Blood smears of the fowls were taken daily, since the first day the fowls were exposed to the ticks, up to the 25th day after exposure (DAE). Blood samples were collected three days before exposure, and three, eight and 18 DAE, for hematologic tests. The examination of Group 1 smears revealed large number of spirochaetes. Group 2 and 3 blood smears were negative during the whole period under exam. In agreement with the hematological evaluation results, the fowls exposed to infected ticks showed a normocytic normochromic anemia in eight DAE, leucocytosis with heterophilia and monocytosis concomitant with the spirochaetemia. We concluded that B. anserina infection determined on fowls of Group 1 hematological alterations compatible with bacterial infection of moderate gravity, developing to self-cure, in the experimental conditions established in this study.

In vitro cultivation and cryopreservation of Babesia bigemina sporokinetes in hemocytes of Rhipicephalus microplus

Cultures of tick hemocytes represent alternative cell lines for the isolation and cultivation of a variety of hemoparasites. The present study reports the development and evaluation of methods for the in vitro culture and maintenance of sporokinetes of Babesia bigemina in association with hemocytes of the tick Rhipicephalus microplus. Hemolymph, from engorged females infected with B. bigemina sporokinetes, was incubated at 28 °C in L15 culture medium supplemented with 40% fetal bovine serum. Adherence of hemocytes to flask surfaces and the development of B. bigemina sporokinetes commenced on the first day of cultivation. The protozoa demonstrated clear motility and the capacity to adhere to hemocyte membranes for up to 25 days, at which time the hemocytes began to show signs of degeneration. Examination of Giemsa stained hemocyte cultures, revealed the presence of pyriformis forms, as well as mature and immature sporokinetes with dark red nuclei, centralized or near the apical extremities. Sporokinetes harvested from culture supernatants were cryopreserved in liquid nitrogen. Inoculation of parasite-free hemocyte cultures with defrosted sporokinetes, demonstrated the viability and interaction of the protozoa with the hemocytes over 21 days. Cultured hemocytes of R. microplus hold potential for development as a tool in the study of host parasite interactions and as a substrate for the in vitro maintenance of B. bigemina sporokinetes.

Assessment of weight gain and biological parameters of Rhipicephalus sanguineus females fed artificially via capillary tubes

This study assesses the weight gain of partially engorged Rhipicephalus sanguineus females that were artificially fed via capillary tubes and the influence of capillary tube feeding on the biological parameters of the non-parasitic stage of the species. The ticks were sorted into four groups, each containing ten females of a homogeneous weight. The groups were each treated for different feeding times, 2, 6, 12 and 24 hours. The weight gain of the artificially fed females was measured, and the biological parameters of the non-parasitic stage of the tick were observed for each treatment group. The statistical non-parametrical Dunn and Kruskal-Wallis tests were used to compare the results. The mean weights (mg) were 0.2±2.4; 4.3±5.8; 7.4±5.8 and 12.0±11.2 for the 2, 6, 12 and 24 hours feeding groups, respectively. The weight of the fed groups increased as the capillary feeding time increased, and this relationship was highly significant (P 0.05) were observed in the parameters of the non-parasitic stage for the artificially fed groups. It can be concluded that artificial feeding via capillary tubes provides an efficient and easy method for the artificial intake of blood by R. sanguineus. Furthermore, it was noted that the ticks fed in vitro were able to establish a new generation. The experimental method shows great promise in studies that aim to investigate biological disease agents.