The effect of temperature and fasting period on the viability of free-living females of Rhipicephalus sanguineus (Acari: Ixodidae) under laboratory conditions.

Little is known about the effect of temperature on viability of free-living phases of the life cycle of Rhipicephalus sanguineus (Latreille, 1806) despite of its importance as vector of several pathogens. Knowledge of the effect of abiotic factors on the capacity of a given tick species to infest new hosts is important for routine experimental activities under laboratory conditions, and may be relevant to understand the transmission of pathogens. The study evaluates the viability of R. sanguineus females held at 18 +/- 1, 27 +/- 1 and 32 +/- 1 degrees C and 80 +/- 5% RH (saturation deficits of 3.0, 5.3 and 7.2 mmHg, respectively) for three fasting periods (3 and 20 days and the day when female mortality reached approximately 50% after ecdysis), under laboratory conditions. In general, the best result on viability was obtained when rabbits were infested with unfed female ticks after three or 20 fasting days at both 27 +/- 1 and 32 +/- 1 degrees C and 80 +/- 5% RH.

Spatial distribution and impact of cattle-raising on ticks in the Pantanal region of Brazil by using the CO(2) tick trap.

This study evaluates the impact of cattle-raising on ticks associated with wildlife in the Pantanal region of Brazil, by trapping free-living ticks using a CO(2) tick trap. The traps were equally distributed in two areas: a 600-ha protected area (PA) and the Nhumirim Ranch (NR). Both areas are contiguous and located at the sub-region of Nhecolândia (18 degrees 59'S; 56 degrees 39'W), Pantanal, Brazil. In each area, four habitat types were selected: cerrado (tropical savanna), forest patches, lakes and soda lakes. The last two are temporary lagoons of fresh and salted water, respectively. A total of 980 nymphs, 613 adults and 13 larvae of ticks Amblyomma were collected in 256 h of collection. In a pen of calves infested by Ornithodoros rostratus 114 specimens were collected, including larvae, nymphs and adults. Adults of A. cajennense and A. parvum were more abundant in the savanna at NR, but not differed among habitat types at PA. There was a tendency of having more nymphs in NR than in PA. The higher number of ticks found in the NR in comparison to the PA is not due to the presence of cattle itself but probably due to introduced dogs and horses, habitat alteration.

Influência do comportamento gregário nos processos de muda de Rhipicephalus sanguineus (Latreille, 1806) (acari: ixodidae), em condições laboratoriais / Influence of aggregation on the molting process of Rhipicephalus sanguineus, (Latreille, 1806) (acari: ixodidae) under laboratory conditions

Objetivou-se com o experimento verificar a influência de diferentes agregações sobre os parâmetros relacionados ao processo de ecdise ninfal e de adulto de Rhipicephalus sanguineus (Latreille, 1806). Foram utilizados como hospedeiros 10 coelhos domésticos (Oryctolagus cuniculus) primos-infestados. Foram analisados os períodos de pré-ecdise, de ecdise e de muda, o percentual e o ritmo de ecdise para todos os estágios estudados. Durante toda a fase não-parasitária, os carrapatos foram mantidos em condições controladas de umidade (80±5 por cento) e temperatura (27±1ºC). Um total de 1560 larvas ingurgitadas e de 1560 ninfas ingurgitadas foi utilizado. Os carrapatos foram divididos em seis grupos contendo um, cinco, dez, 20, 40 e 80 espécimes cada. Para cada um desses grupos foram realizadas dez repetições. Os processos de ecdise ninfal e de adulto foram acompanhados diariamente. Após a análise dos resultados, verificou-se que não houve relação entre as diferentes agregações e o percentual de ecdise em nenhuma etapa experimental. Em todos os outros parâmetros biológicos estudados, verificaram-se diferenças significativas (p<0,05). Os resultados obtidos sugerem que em elevadas agregações o processo de ecdise tende a ser mais rápido.

The objective of this experiment was to evaluate the influence of different aggregations on the molting process of Rhipicephalus sanguineus (Latreille, 1806). Tick-naïve domestic rabbits (Oryctolagus cuniculus) were used as experimental hosts for the parasitic phase. A total of 10 rabbits were used on the experiment. All tick free-living phases were kept in incubator at 27±1ºC, 80±5 percent relative humidity and scotophase. The periods of pre-molt, molt, percentage of ecdisis and molt rhythm of larvae and nymphs were studied. A total of 1560 engorged larvae and 1560 nymphs of R. sanguineus were divided in six groups of aggregations: 1, 5, 10, 20, 40 and 80 ticks with ten repetitions each one. The ecdises of nymphs and adults were daily observed. The percentage of ecdysis was the only parameter with no aggregations effects. All others parameters were statistically different (p<0,05). The results suggested that highest aggregations accelerate the molting process.

[Influence of aggregation on the molting process of Haemaphysalis leporispalustris (Acari: Ixodidae) under laboratory conditions]. / Influência do comportamento gregário nos processos de muda de Haemaphysalis leporispalustris (Acari: Ixodidae) em condições laboratoriais.

The aim of the experiment was to evaluate the influence of different aggregations on the molting process of the nidicoulus ticks, Haemaphysalis leporispalustris. Tick-naïve domestic rabbits (Oryctolagus cuniculus) were used as experimental hosts for the parasitic phase. All free-living phases were kept into 4.5 mL glass vials in incubators at 27+/-1 degrees C, 80+/-15% relative humidity and scotophase. The periods of pre-molt, molt, percentage of ecdisis and molting pattern of larvae and nymphs were studied. A total of 1560 engorged larvae and nymphs were divided in six groups of aggregations: 1, 5, 10, 20, 40 and 80 ticks with ten repetitions. The molting of nymphs and adults were observed daily. The percentage of ecdysis was the only parameter with no statistical difference among the groups (p>0.05). All others parameters were statisticaly different (p<0.05). The results suggested that highest aggregations accelerate the molting process of H. leporispalustris. We recommended the following aggregations: 4.4 ticks/ml for scientific research and less than 7.7 tick/ml for ticks maintenance.

[Influence of aggregation on the molting process of Rhipicephalus sanguineus, (Latreille, 1806) (Acari: Ixodidae) under laboratory conditions]. / Influência do comportamento gregário nos processos de muda de Rhipicephalus sanguineus (latreille, 1806) (acari: ixodidae), em condições laboratoriais.

The objective of this experiment was to evaluate the influence of different aggregations on the molting process of Rhipicephalus sanguineus (Latreille, 1806). Tick-naïve domestic rabbits (Oryctolagus cuniculus) were used as experimental hosts for the parasitic phase. A total of 10 rabbits were used on the experiment. All tick free-living phases were kept in incubator at 27+/-1 degrees C, 80+/-5% relative humidity and scotophase. The periods of pre-molt, molt, percentage of ecdisis and molt rhythm of larvae and nymphs were studied. A total of 1560 engorged larvae and 1560 nymphs of R. sanguineus were divided in six groups of aggregations: 1, 5, 10, 20, 40 and 80 ticks with ten repetitions each one. The ecdises of nymphs and adults were daily observed. The percentage of ecdysis was the only parameter with no aggregations effects. All others parameters were statistically different (p<0,05). The results suggested that highest aggregations accelerate the molting process.

[The effect of immersion in distilled water on the engorged larvae and nymphs of Amblyomma dubitatum Neumann, 1899 (Acari: Ixodidae)]. / Efeito da imersão de larvas e ninfas ingurgitadas de Amblyomma dubitatum Neumann, 1899 (Acari: Ixodidae) em água destilada.

To evaluate the effect of the immersion of engorged larvae and nymphs of Amblyomma dubitatum experimentally fed on rabbits, the ticks were collected and formed control groups, without immersion, and groups witch were immersed by 24, 48, 72, 96 hours and, for engorged larvaes, by eight weeks, in test tubes containing distilled water. During all experiment ticks were kept at 27 +/- 1 degrees C, 80 +/- 10% RU and scotophase The parameters evaluated were: pre-ecdysis, ecdysis and moulting periods; and ecdysis and mortality percentages. When compared with the control group, the effect (p<0,05) of immersion varied intra and inter stages. Apparently, immersion was less deleterious to A. dubitatum in comparison with A. cajennense and R. sanguineus from neotropical region, thus reflecting a long host relations with the capybara, its primary host.

[Infestation with Linognathus africanus (Kellogg e Paine, 1911) (Linognathidae) and Bovicola caprae (Ewing, 1936) (Trichodectidae) in goat flock of the State of Rio de Janeiro, Brazil]. / Infestações por Linognathus africanus (Kellogg e Paine, 1911) (Linognathidae) e Bovicola caprae (Ewing, 1936) (Trichodectidae) em rebanho caprino no Estado do Rio de Janeiro.

Mixed infestations with Linognathus africanus and Bovicola caprae were diagnosed in a lot of 20 goats from a flock of 40, belonging to a farm from the Universidade Federal Rural do Rio de Janeiro, Rio de Janeiro, RJ (22 degrees 44'38''S and 43 degrees 42'27''W). Animals were of both sexes, varied ages and different breeds (half blood Saanen/Boer, Saanen, cross breeds), were examined in April of 2004. With an exception of one goat, parasitized only by L. africanus, the remainders 19 (95%) were infested by the two species lice. Of 69 (71%) specimens of L. africanus and 28 (28.9%) of B. caprae collected the ratio female:male for L. africanus were 4.6 (23:5), while for B. caprae were 4.8 (57:12). The absence of L. africanus in recent surveys carried out in the semi-arid regions of the Northeast Brazil where more the 60% of examined goats were parasitized by B. caprae suggests that the adaptation to the climatic variation might be different for the two species.