Biology of the non-parasitic phase of the cattle tick Rhipicephalus (Boophilus) microplus in an area of Amazon influence.

BACKGROUND: Rhipicephalus (Boophilus) microplus is the most important tick species affecting cattle in the world. Under field conditions, the non-parasitic phase of R. (B.) microplus is unknown in the Amazon biome, including Brazil. The present study aimed to evaluate the non-parasitic phase of R. (B.) microplus in field (grass plots) and laboratory conditions. METHODS: The study was conducted from September 2020 to April 2022 in an Amazonian region (Maranhão State, Brazil). We evaluated the biological parameters of R. (B.) microplus under laboratory and field conditions. Engorged females were exposed to experimental conditions every 14 days, totaling 20 months of study. The following biological parameters were observed: pre-oviposition period, egg mass incubation period, and maximum larval survival period. RESULTS: Abiotic data (e.g., temperature and humidity) varied little throughout the year. Precipitation was the factor that varied the most throughout the year (dry ~ 30 mm3 and rain 400 mm3), and the parameters of pre-oviposition and pre-hatching are longer during the rainy season. A possible negative effect of the dry season on the percentage of hatched eggs was observed. Larval longevity in the plots of both control and free females was short (mean ~ 50-60 days), below that recorded for larvae under controlled conditions (mean ~ 95 days). CONCLUSIONS: Rhipicephalus (Boophilus) microplus was able to complete its non-parasitic phase by producing host-seeking larvae in the pasture during all months of the study. The results indicate that R. (B.) microplus can complete up to six generations per year in biome Amazon. To our knowledge, this is the highest number of annual generations for R. (B.) microplus in Latin America.

Acute coronary syndrome remodels the antiplatelet aggregation properties of HDL particle subclasses.

Essentials HDL subclasses were studied in acute coronary syndrome (ACS). HDL2 from ACS patients have better antiplatelet potency than HDL from non ACS subjects. ACS remodels the antiplatelet properties of HDL subclasses. Oxidized polyunsaturated fatty acids content of HDL is modified by ACS. SUMMARY: Background Although HDLs have antithrombotic effects by reducing platelet activation, the relationship between HDL levels and the risk of acute coronary syndrome (ACS) is unclear, as HDL particles are heterogeneous in composition and biological properties. Objective To characterize the effects of HDL2 and HDL3 subclasses from ACS patients and non-coronary artery disease (CAD) subjects on platelet activation. Methods We measured platelet aggregation and ex vivo thrombus formation, analyzed signaling pathways by flow cytometry, and performed a targeted lipidomics analysis on HDL subclasses. Results Analysis of human platelet aggregation in suspension, adhesion on von Willebrand factor and thrombus formation on collagen under arterial shear demonstrated that HDL2 from ACS patients had higher antiplatelet potency than HDL3 from ACS patients and HDL from non-CAD subjects. HDL binding to scavenger receptor class B type I was essential for this effect. A lipidomics analysis revealed that HDL2 from ACS patients had more oxidized polyunsaturated fatty acids (PUFAs). An inverse correlation between the concentrations of 9-hydroxyoctadecadienoic acid (9-HODE), 13-hydroxyoctadecadienoic acid (13-HODE), the eicosapentaenoic acid metabolite 18-hydroxyeicosapentaenoic acid (18-HEPE) and hydroxyeicosatetraenoic acid isomers in HDL2 and platelet aggregation was observed. This relationship was further demonstrated by the direct inhibitory effects of 18-HEPE, 9-HODE, 13-HODE, 17-hydroxydocosahexaenoic acid and 14-hydroxydocosahexaenoic acid on collagen-related peptide-induced platelet aggregation, indicating that oxidized PUFAs contribute to the antithrombotic effect of ACS HDL2. Conclusions Our data shed new light on the antiplatelet effects of HDL subclasses, and suggest physiological adaptation through the modulation of HDL properties in ACS patients that may limit their platelet-dependent thrombotic risk.

Life Cycle of Amblyomma romitii (Acari: Ixodidae) Under Laboratory Conditions.

The life cycle of Amblyomma romitii Tonelli-Rondelli, 1939 is reported for the first time, using rabbits (Oryctolagus cuniculus) for larvae and capybara (Hydrochoerus hydrochaeris) for nymphs and adults, as experimental hosts. Developmental periods of free-living stages were observed in an incubator at 27 ± 1°C, 80 ± 10% relative humidity (RH), and 24-h darkness. The life cycle of A. romitii in the laboratory could be completed in an average period of 216.4 d. The overall sex ratio (M:F) was 1:1.4. The results showed that rabbits are quite suitable as experimental hosts for the larval stages of A. romitii, while capybaras are suitable experimental hosts for nymphs and adults.

Host-Parasite Relationship of Ticks (Acari: Ixodidae and Argasidae) and Feral Pigs (Sus scrofa) in the Nhecolândia Region of the Pantanal Wetlands in Mato Grosso do Sul.

Feral pigs (S. scrofa) were introduced to the Pantanal region around 200 years ago and the population appears to be in expansion. Its eradication is considered to be impossible. The population of feral pigs in the Pantanal wetlands is currently estimated at one million. Two scientific excursions were organized. The first was conducted during the dry season, when 21 feral pigs were captured and the second was during the wet season, when 23 feral pigs were captured. Ticks were collected and the oviposition and hatching process were studied to confirm the biological success of each tick species. Three tick species were found to be feeding on feral pigs: Amblyomma cajennense, A. parvum, and Ornithodoros rostratus. During the dry season, 178 adult A. cajennense were collected, contrasting with 127 A. cajennense specimens in the wet season. This suggests that the seasonality of these ticks in the Brazilian Pantanal wetlands could be different from other regions. The results indicate that A. parvum and A. cajennense are biologically successful parasites in relation to feral pigs. A. cajennense appears to have adapted to this tick-host relationship, as well as the areas where feral pigs are abundant, and could play a role in the amplification of this tick population.

Redescription of Amblyomma varium Koch, 1844 (Acari: Ixodidae) based on light and scanning electron microscopy

Amblyomma varium Koch, 1844 is a Neotropical tick, known as the 'sloth's giant tick', with records from southern Central America to Argentina. It is found almost exclusively on mammals of the families Bradypodidae and Magalonychidae (Xenarthra). Differences exist in discussions with regard to the dentition of the female hypostome being either 3/3 or 4/4. The male was also originally described as having a short spur on coxa IV, but some specimens recently collected from different Brazilian localities have this spur three times longer. These differences beg the question of whether there is more than one species included under this taxon. In order to answer this question and to clarify the taxonomic characters of this species, 258 adult specimens were examined, and a redescription of male and female based on light and scanning electron microscopy is provided. In addition, DNA was extracted from males with either a long or a short spur on coxa IV to help settle this question for future investigations on their taxonomy. The morphological study showed that the dental formula pattern for males and females is 3/3 and 4/4, respectively. When sequenced, the 12 S rDNA genes of both A. varium males with long and short spurs on coxa IV were found to be identical, indicating that the length of the spurs on coxa IV is likely to be an intraspecifically polymorphic character of this species.

Rabbits (Oryctolagus cuniculus) as experimental hosts for Amblyomma dubitatum Neumann (Acari: Ixodidae)

O ciclo biológico do Amblyomma dubitatum, que se alimentava experimentalmente em coelhos domésticos, foi avaliado em condições laboratoriais e comparado com dados recentemente obtidos de infestações experimentais em capivaras (Hydrochaeris hydrochaeris), hospedeiros naturais para essa espécie. Os coelhos foram considerados hospedeiros experimentais adequados para larvas e ninfas porque quatro dos cinco parâmetros avaliados (número de carrapatos que ingurgitaram, período de alimentação, percentagem de carrapatos que realizaram muda e período de pré-muda) foram semelhantes aos resultados obtidos com capivaras. As percentagens diárias de desprendimento e de muda das larvas e ninfas confirmam os coelhos como hospedeiros experimentais adequados para esses estágios de A. dubitatum. Os resultados do experimento indicam que os coelhos são hospedeiros inadequados para os adultos.

Occurrence of Struthiopterolichus bicaudatus (Acari; Pterolichidae) in Southeastern Brazil

A ocorrência de Struthiopterolichus bicaudatus é assinalada em uma criação de avestruz no estado de Minas Gerais. Os principais sinais associados com a presença dos ácaros foram penas quebradas com a falta de barbas no vexilo, principalmente nas penas das asas, e prurido. Esses sinais foram observados em todas as aves do plantel (285 animais) com idade acima de 13 meses. As aves com idade abaixo de 13 meses (60 animais) não apresentaram qualquer sinal, tampouco ácaros.

Experimental infestation with the immatures of Amblyomma dissimile Koch, 1844 (Acari: Ixodidae) on Tropidurus torquatus (Lacertilia: Iguanidae) and Oryctolagus cuniculus

Larvas provenientes de duas fêmeas de Amblyomma dissimile Koch, 1844 (Acari: Ixodidae), naturalmente ingurgitadas em uma iguana (Iguana iguana) e provenientes do Estado do Mato Grosso, foram utilizadas na infestação experimental de lagartos da espécie Tropidurus torquatus e coelhos domésticos. As larvas alimentadas em ambos os hospedeiros realizaram ecdise para ninfas. As ninfas apenas ingurgitaram no lagarto e mudaram para machos e fêmeas. Este é o primeiro registro do parasitismo de larvas e ninfas de A. dissimile em T. torquatus e de larvas em coelhos.

The sex ratio of Amblyomma cajennense (Acari: Ixodidae) with notes on the male feeding period in the laboratory.

To evaluate the sex ratio of field collected nymphal Amblyomma cajennense ticks, we collected 5326 engorged nymphs from naturally infested horses in Pirassununga county and allowed them to molt to adults in the laboratory. They yielded a sex ratio of 1:1.83 (M:F). Three and two engorged females were collected from horses pastured at Pirassununga county and from tapirs pastured in Sorocaba county, respectively. These females were allowed to oviposit and their progeny were reared until the adult stage in the laboratory. Engorged females collected from Pirassununga yielded a sex ratio of 1:1.57 (M:F) and a sex ratio of 1.14:1 (M:F) were obtained for those ticks collected from tapirs. In addition, unfed tick larvae were collected from Pedreira county and reared in the laboratory until the adult stage. This collection yielded a sex ratio of 1.11:1 (M:F). These results showed significantly different (P<0.05) sex ratio constitutions among different tick populations. Laboratory rabbits were infested once with A. cajennense male ticks, which showed feeding periods varying from 7 to 86 days. During this period, the rabbits were re-infested regularly with A. cajennense female ticks. A total of 179 engorged females were collected from the rabbits and their engorged weight, feeding, preovioposition and egg incubation periods, weight of deposited eggs, percent of hatched eggs and egg production efficiency were compared to the male feeding period and to the number of live males present on the host. None of the female variables were affected by the male feeding period. Male ticks remained fertile for the whole feeding period. Percent of hatched eggs was the only female variable that significantly decreased as the number of live males decreased on the host. The results showed that although some A. cajennense populations are composed of more females than males after molting, this female predominance is compensated by a long male feeding period and maintenance of its reproductive performance.

Life cycle of female ticks of Amblyomma cooperi Nuttal & Warburton, 1908 (Acari: Ixodidae) under laboratory conditions

The biological cycle of female ticks of Amblyomma cooperi was studied under controlled conditions. The study has begun with two engorged females collected in a naturally infested wild capybara. The larvae originated from the oviposition of these two females were used for collecting young adults through artificial infestations in rabbits. The female parasitic and free living phases were evaluated using artificial infestation of ticks in a capybara. The average body weight of female was 958.2+/-175.6mg, the average pre-egg laying period was 8.5+/-1.4 days, the reproductive efficiency index was 59.5+/-4.2 and the nutritional efficiency index was 77.3+/-4.8. The incubation and eclosion periods were 41.0 and 5.0 days, respectively, and the rate of eclosion was 64 per cent. These figures were obtained under hight relative humidity conditions which were necessary for the sucess of the egg incubation process of this species. The preliminary data obtained with the artificial infestation in rabbits raises the possibility of this and other domestic species be used as an epidemiologic link between the domestic and the wild environment with the potential exposure of human populations to A. cooperi and to the maculosa fever agent

Risk factors to tick infestations and their occurrence on horses in the state of São Paulo, Brazil.

From December 1998 to March 1999, 40 stud farms were studied in the state of São Paulo, Brazil. During visits to farms, horses reared under grazing conditions were examined for the presence of ticks. On each farm visit, horse pastures were closely inspected and a questionnaire was given to the farm supervisor with the purpose of gaining information about ecological and management variables (independent variables) that could be associated with the presence and infestation levels of ticks on the farm (dependent variables). Three tick species were found during the study. Anocentor nitens, Amblyomma cajennense and Boophilus microplus were present on horses from 38 (95%), 20 (50%) and four (10%) farms, respectively. All farms that had A. cajennense or B. microplus infestations also had A. nitens infestations. Only one of the four farms with B. microplus infestations on the horses also had A. cajennense infestations. Two farms had all horses free of ticks. There was a strong association between the presence of infestation by B. microplus on horses and the simultaneous use of a grazing area by cattle and horses (P = 0.000). There was no statistical association between any of the independent variables and the presence or infestation level of A. nitens on the horses (P > 0.20). The presence of A. cajennense was statistically associated with the presence of at least one mixed overgrowth pasture in the farm (P = 0.001). A mixed overgrowth pasture means the presence of undesired plants such as bushes and shrubs in the pasture. The presence of high levels of A. cajennense on horses was also associated with the presence of at least one mixed overgrowth pasture in the farm (P = 0.026). The regular use of acaricides was statistically associated with the presence of ticks on the horses (P < 0.05), making this procedure a result of the inefficacy of controlling ticks on the farms. The occurrence of human infestation by ticks was statistically associated with the presence of A. cajennense on the horses (P=0.000). The presence of at least one mixed overgrowth pasture on the farm was associated (P = 0.000) to either higher horse densities and to farms that did not mow all the pastures once a year, indicating that mowing all the pastures at least once a year can be considered a protective factor against the presence of mixed overgrowth pastures on the farm, and consequently, against the presence of A. cajennense on the horses.

Exotic ticks on horses imported from Portugal to Brazil

Em abril de 1999, cinco espécimens de carrapatos foram colhidos de dois eqüinos que haviam chegado há um dia de Portugal em uma propriedade rural no interior do Estado de Sao Paulo. Os carrapatos foram enviados vivos ao laboratório e foram identificados como Hyalomma marginatum e Rhipicephalus bursa. Esta última espécie foi criada em laboratório para obtençäo de novos adultos para confirmaçäo da identificaçäo. Tanto H. marginatum como R. bursa säo espécies consideradas restritas ao Velho Mundo, onde atuam como vetores de vários patógenos para os animais domésticos. Os procedimentos técnicos realizados com o objetivo de prevenir um possível estabelecimento desses carrapatos na propriedade rural säo descritos

Life cycle of the tick Haemaphysalis leporis-palustris (Acari: Ixodidae) under laboratory conditions.

The life cycles of two separate populations (colonies A and B) of the rabbit tick, Haemaphysalis leporis-palustris, were studied under laboratory conditions. Domestic New Zealand rabbits, Oryctolagus cuniculus, and wild rabbits, Sylvilagus brasiliensis, were used as hosts for ticks from colony B and only O. cuniculus rabbits were used as hosts for ticks from colony A. Developmental periods were observed in an incubator at 27+/-1 degrees C and RH 90+/-5%. Larvae from colonies A and B fed for 8.0+/-3.7 days and 8.5+/-1.3 days, respectively, on O. cuniculus. On S. brasiliensis larvae from colony B fed for 7.2+/-1.3 days. Nymphs from colony A fed for 8.1+/-1.4 days on O. cuniculus and nymphs from colony B fed for 8.1+/-1.0 days on S. brasiliensis. Only one engorged nymph from colony B was recovered from O. cuniculus. Females from colony A fed for 20.9+/-5.9 days on O. cuniculus and females from colony B fed for 18.6+/-2.4 days on O. cuniculus and 18.7+/-3.7 days on S. brasiliensis. Engorged larvae from colony A required 13.7+/-3.7 days to molt while engorged larvae from colony B required 11.8+/-3.0 and 11.5+/-1.8 days to molt, after having fed on O. cuniculus and S. brasiliensis, respectively. Engorged nymphs from colonies A and B required 16.3+/-1.9 days and 14.7+/-1.4 days to molt, respectively. Engorged females from colonies A and B required 4-7 and 3-5 days, respectively, to start oviposition. Mean egg incubation periods lasted for 33-34 days. For ticks from colony B, host species accounted for significant differences (p < 0.05) in larval and nymphal feeding periods, oviposition weights and CEIs. Significant differences (p < 0.05) between the two colonies when ticks fed on O. cuniculus were observed for larval and nymphal feeding and premolt periods, engorged female and oviposition weights and conversion efficiency indexes (CEI). S. brasiliensis were always a more suitable host for H. leporis-palustris than O. cuniculus. Significantly more larvae and nymphs engorged and molted when fed on S. brasiliensis (p < 0.001). Females fed S. brasiliensis were more successful to lay fertile eggs and showed the highest engorged and egg mass weights, and the highest CEIs. Data of H. leporis-palustris fed on wild rabbits (one of its natural host species) are reported for the first time.

Características biológicas da fase näo parasitária do Ixodes amarali (Acari: Ixodidae) em gambá (Didelphis sp.) no Estado do Rio de Janeiro / Biological characteristics of the non-parasitic phase of Ixodes amarali (Acari: Ixodidae) from opossum (Didelphis sp.) in the State of Rio de Janeiro, Brazil

Ixodes amarali was reported for the second time in the State of Rio de Janeiro, southeastern Brazil, from an engorged female obtained from a naturally infested opossum (Didelphis sp.). Biological characteristics of de non-parasitic phase were studied, under controlled conditions (temperature of 27ñ1§C, relative humidity higther than 80 per cent and scotophase)

An improved method for the recovery of mycoplasmas from the external ear canal of goats.

The efficacy of ear canal flushing and ear canal and mouth swabbing methods for the isolation of mycoplasmas was investigated in 39 goats. Of the 19 goats positive for Mycoplasma spp., 14 (73.7%) were positive with the ear canal flushing method, 4 (21.0%) were positive with both ear canal flushing and mouth swabbing methods, and 1 (5.3%) was positive by the mouth swabbing method. Mycoplasma arginini, M. mycoides subsp. mycoides, and M. mycoides subsp. capri were identified by direct immunofluorescence and growth inhibition tests. Previous reports on the isolation of M. arginini from the ear canal of goats were not found in the literature.

Subclinical psoroptic otocariasis in Brazilian sheep with comments on a technique for mite collection.

Subclinical psoroptic otocariasis associated with Psoroptes cuniculi (Delafond) was diagnosed in four out of ten herds of sheep. Transmission of mites between sheep and goats and vice versa was detected in herds kept on the same pastures for over 2 years. Flushing the ear canals of sheep and goats with approximately 50 ml of water appeared to be more efficient than swabbing or otoscopic examination for diagnosis and/or mite collection.

Description of Raillietia flechtmanni sp. n. (Acari: Gamasida).

Raillietia flechtmanni sp. n. is described from the ear canal of its type host the domestic buffalo. The new species parasitizes cattle as well in Brazil.