Detection of Rickettsia tamurae-like and other spotted fever group rickettsiae in ticks (Acari: Ixodidae) associated with wild birds in the Western Amazon, Brazil.

Ticks are vectors for several pathogens, including bacteria belonging to the Rickettsia genus, such as Rickettsia rickettsii and Rickettsia parkeri, the causative agents of spotted fever. The aim of the present study was to investigate the tick species richness and rickettsial agents associated with wild birds captured in the Humaita Forest Reserve, Acre, in the Western Amazon region. Wild birds were captured with ornithological nets for visual inspection with the purpose of collecting ticks, which were identified through morphological analyses and molecular tests for several genes (12S rDNA, 16S rDNA, gltA, ompA, and sca4). A total of 607 wild birds were captured, 12% of which were parasitized by 268 ticks of the Amblyomma genus, with new host-parasite associations reported for Amblyomma calcaratum, Amblyomma geayi, Amblyomma longirostre, Amblyomma naponense, Amblyomma nodosum, and Amblyomma varium. Of the total ticks collected, 113 were tested for the presence of rickettsial DNA fragments, with 19 testing positive for R. parkeri in A. geayi, Rickettsia tamurae-like in Amblyomma sp., and Rickettsia amblyommatis in A. geayi, A. longirostre, and Amblyomma sp. We detected R. tamurae-like in Amblyomma larvae for the first time in the Western Brazilian Amazon biome, and registered spotted fever group rickettsiae, although the relevance of the detected species in a public health context should be further explored in South America, as well as new host-parasite interactions in this underexplored region.

The bioactive compound carvacrol as a potential acaricide: An assessment of its effects on the integument of female Rhipicephalus sanguineus sensu lato ticks.

Studies seeking control methods for infestation of Riphicephalus sanguineus sensu lato (s.l.) ticks (dog ticks) have been carried out in order to minimize damage to both the tick's hosts and the environment, the latter due to the misuse of acaricide products. In this regard, carvacrol has been used as a natural alternative against ticks as it displays several properties including acaricidal. In this context, the present study aimed to evaluate the ultramorphology and morphohistochemistry of the integument of semi-engorged R. sanguineus s.l. females exposed to different carvacrol concentrations. The findings indicate that the integument surface of females exposed to the highest carvacrol concentration (25 µl/ml) became wrinkled, suggesting dehydration or the result of integument cuticular and epithelial layer disorganization in response to the toxic product. Morphohistochemical integument layer alterations were more significant and intense in females exposed to the highest carvacrol concentration (25 µl/ml), confirming dose-dependent carvacrol action. Among other cell and tissue alterations, changes in epithelial cell shape, size, and arrangement (epidermal layer) were noted, alongside altered and pyknotic-shaped nuclei, suggesting a death process for these cells. This epithelium changed from simple cubic to stratified, also in response to the presence of the evaluated bioactive compound. Thus, the findings reported herein demonstrate that carvacrol may be an alternative for an efficient and more sustainable tick control in the near future.

Exposure of Rhipicephalus sanguineus sensu lato Latreille, 1806 (Acari: Ixodidae) to hexane extract of Acmella oleracea (Jambu): semi-engorged and engorged ticks.

The present study analyzed the efficacy of hexane extract of Acmella oleracea against Rhipicephalus sanguineus sensu lato. After exposure of R. sanguineus s. l. female ticks to 14 different concentrations of the hexane extract of A. oleracea, the LC50 was established as 18.135 mg/mL (limits: 16.251-22.675). The effects of the extract were more significant in the ovary of the semi-engorged females, that presented damages in most oocytes. Since such changes would not be repaired, the oocytes could not advance to further stages of development (I-V), thereby causing the inhibition of ovary development, interruption of vitellogenesis, oocyte death and, consequently, infertility. The semi-engorged females also presented extensive damages in the midgut cells, which would prevent (totally or partially) these cells from functioning properly (blood intake and release of nutrients), impairing the ectoparasite nutrition and the viability of the individual. Thus, the hexane extract of A. oleracea can be considered as a promising alternative to chemical control of pests of medical and veterinary importance, due to its efficient acaricidal activity and lesser environmental impact, when used against female ticks in the middle feeding stage.

Thymol: Effects on reproductive biology and Gene's organ morphology in Rhipicephalus sanguineus sensu lato engorged females (Acari: Ixodidae).

Thymol is a monoterpene with proven acaricidal activity on different tick species and life stages. The objective of this work was to evaluate the effect of thymol on the reproductive biology of engorged females of Rhipicephalus sanguineus sensu lato and the morphological changes caused in the cells of the tubular and accessory glands of Gené's organ. The females were exposed to thymol by immersion. Seven groups were established: group I (distilled water), group II (30% ethanol), group III (thymol 1.25 mg/mL), group IV (thymol 2.5 mg/mL), group V (thymol 5.0 mg/mL), group VI (thymol 10.0 mg/mL), and group VII (thymol 20.0 mg/mL), with 20 replicates for each treatment. The ticks were kept in a BOD incubator at 27 ±â€¯1 °C and RH > 80 ±â€¯10%. Ten females from each group were evaluated daily until death, and the remaining ten were kept in the incubator under the same conditions for five days and then dissected for the removal of Gené's organ to note possible damage to cell morphology by scanning electron microscopy (SEM) and hematoxylin-eosin (HE) techniques. Thymol demonstrated 63% and 98% efficacy in groups VI (10.0 mg/mL) and VII (20.0 mg/mL), respectively. In these groups, the cells of the tubular and accessory glands of Gené's organ showed signs of damage: irregular eosin staining, rupture and deformation of the cellular limit, presence of fragmented nuclei, changes in cytoplasmic homogeneity and areas with deformation (folds) in the basal region.

Cytotoxic Effects of Extract of Acmella oleracea in the Ovaries and Midgut of Rhipicephalus sanguineus Latreille, 1806 (Acari: Ixodidae) Female Ticks.

The present study investigated the effects of different concentrations of Acmella oleracea extract on the germinative cells and digestive processes of semi-engorged Rhipicephalus sanguineus females. For this experiment, 150 ticks were divided into five groups (30 individuals each). The animals were immersed for 5 min in different concentrations of the extract, distilled water, or ethanol 50%/DMSO 1%, dried, and kept in biological oxygen demand incubator for 7 days. The alterations were associated with the size of germinative cells and yolk granules; presence, size, and location of vacuoles in the cytoplasm of germinative cells; nuclear modifications in the germinative cells; damages to the nucleus and cytoplasm of the midgut generative cells; size of digestive cells; number of captured blood elements; accumulated digestive residues and digestive vacuoles in the digestive cells cytoplasm; and the number and distribution of proteins and polysaccharides in all the cells of both organs. The concentrations used in this study prevented an efficient and complete blood digestion by the midgut epithelial cells of the treated animals, resulting in the absence of the necessary nutrients to maintain the physiological events in the ectoparasites. In advanced stages, This can lead the ectoparasite to death. The germinative cells were highly impaired and probably not able to advance developmental stages (I-V) or complete vitellogenesis to be released during ovulation, which would prevent the females from originating a new individual. Thus, it can be concluded that the effects of A. oleracea are similar to those caused by chemical products widely recognized as effective to control ticks.

Cytotoxic effects of Euterpe oleraceae fruit oil (açaí) in rat liver and thyroid tissues

Abstract Euterpe oleracea Mart., Arecaceae, fruit (açaí) presents considerable potential for the development of new medicines due to its phytochemical composition and antioxidant activity. More recently, special attention has been given to the pharmacological potential of the fruit's oil. This study analysed the histological and histochemical effects of different dosages of açaí oil on rat's liver and thyroid cells, in order to evaluate its cytotoxic potential after administration for consecutive days. Male Wistar rats were treated with the açaí oil by gavage at doses of 30, 100 and 300 mg/kg, for 14 days, within a 24 h interval. Liver and thyroid fragments were collected for histology (hematoxylin and eosin) and histochemistry analysis (blue of Nilo (lipids), Baker (lipids), bromophenol blue (protein), PAS (polysaccharides)). The results showed that animals exposed to açaí oil presented alterations in the liver cells, where the integrity of the liver tissue was increasingly lost as the açaí oil doses increased. Nuclear pyknosis was observed in several hepatocytes, evidencing the occurrence of cell death. Alteration in the amount of lipids, polysaccharides, vacuoles in the cytoplasm, and proliferation of Kupffer cells were observed in histochemical analyzes. As for the thyroid of the treated rats, alterations were observed in the size of the follicular lumen and also in the connective tissue found between the follicles. Under the experimental conditions employed in the present study, the cytotoxicity observed in this work is worrying, specially considering the liver, when frequent or continuous damage could lead pathological disorders in this organ.

Effects of carvacrol on oocyte development in semi-engorged Rhipicephalus sanguineus sensu lato females ticks (Acari: Ixodidae).

Currently, the most commonly used method to control ticks is the use of synthetic acaricides. However, these compounds are potentially harmful to hosts and the environment, in addition to causing the selection of resistant individuals. Therefore, several studies have been conducted to find sustainable methods to control ticks, such as Rhipicephalus sanguineus sensu lato, the most important vectors of pathogens for dogs. There has been increasing research on natural products with acaricidal action, especially with regard to plant-derived compounds as carvacrol, an aromatic monoterpene with several biological properties, including repellent and acaricidal activities, besides exerting cytotoxic effects on the exposed ticks. The objective of the present study was to evaluate the action of different carvacrol concentrations on the ovaries morphophysiology in semi-engorged R. sanguineus s.l. females to determine its effect on oocyte development. The results showed the occurrence of significant morphological alterations in the shape of oocytes (from round-shaped to irregular) and in the germinal vesicles, in addition to extensive cytoplasmic vacuolation.These effects were observed after the application of carvacrol at a concentration of 20 µL/mL. The most significant alterations were observed at the highest concentration (100 µL/mL), at which the oocytes could not develop further than stage II (total absence of oocytes III, IV and V). These data showed that even though carvacrol was unable to kill all ticks at these concentrations, surviving females could have had an altered reproduction, which would hinder the generation of new individuals, resulting in a long-term control. Data regarding the inhibition of oocyte development are unprecedented and indicate the use of carvacrol as a natural product with the potential to control R. sanguineus s.l. ticks.

Spilanthol, the Principal Alkylamide from Acmella oleracea, Attenuates 5-Fluorouracil-Induced Intestinal Mucositis in Mice.

Mucositis is one of the commonest side effects in cancer patients undergoing treatment with radiotherapy and/or chemotherapy, and it currently lacks appropriate and effective treatment. Acmella oleracea, a species of flowering herb from South America, contains spilanthol, an alkylamide that has several pharmacological properties, including anesthetic, analgesic, and anti-inflammatory activities. Therefore, the purpose of this work was to evaluate the effect of spilanthol in intestinal mucositis in Swiss mice induced by 5-fluorouracil (5-FU), an antineoplastic agent administered systemically for the treatment of many different cancers. The repeated administration of 5-FU resulted in intestinal mucositis and consequent decreased food intake, together with weight loss, in all the animals. Daily administration of spilanthol significantly lowered the severity of intestinal mucositis, reducing histopathological changes and increasing the villus height in the animals treated with spilanthol at a dosage of 30 mg/kg (p < 0.0044) compared to a group exposed only to 5-FU. A decrease of myeloperoxidase activity was also observed in the animals treated with 30 mg/kg of spilanthol (p < 0.05), although several pro-inflammatory cytokines were not quantifiable in any group. In conclusion, the data demonstrated that spilanthol effectively reduced inflammation in a mouse model of intestinal mucositis induced by 5-FU, and that the compound might be a promising therapeutic candidate for the prevention and treatment of this condition.

Morphological alterations in the ovaries of Amblyomma cajennense semi-engorged ticks exposed to ethanolic extract of Acmella oleracea.

The present study analyzed the effects of different concentrations of Acmella oleracea crude ethanolic extract (EEAO) on the development of germ cells from semi-engorged Amblyomma cajennense females in order to evaluate the potential of this natural chemical as a strategy to control these important ectoparasites. A hundred semi-engorged females were divided into five groups (duplicates) (10 animals/group): Control 1 (distilled water); Control 2 (solvent ethanol 50% and DMSO 1%); and Treatment I to III (3.1, 6.2, and 12.5 mg/mL of EEAO, respectively). For the exposure of the ticks to the extract was used the Adult Immersion Test. After the exposition, the ovaries were removed and submitted to histological analysis using Harris hematoxylin and aqueous eosin. The histochemical tests were performed using PAS and Bromophenol blue staining techniques, for the detection of total polysaccharides and total protein, respectively. The extract caused significant alterations in the oocytes, including changes in the shape of the cells, disorganization, and cytoplasmic vacuolation, decrease in the number of yolk granules and germ vesicle fragmentation. These alterations were more intense in the oocytes in initial developmental stages (I and II). The results obtained in this study confirm the cytotoxic potential of the ethanolic extract of A. oleracea on the germ cells of A. cajennense females, opening up the possibility to use this extract as an alternative to control these ectoparasites.

In vivo study of a homeopathic medicine against Rhipicephalus (Boophilus) microplus in dairy cow

ABSTRACT The tick Rhipicephalus (Boophilus) microplus (Canestrini, 1887) (Acari: Ixodidae) causes large economic losses to cattle breeders and its control is hampered by problems of resistance to the main commercial synthetic acaricides and the risk of residues in animal products. Alternative controls are important for the sustainability of cattle breeding in tropical regions, principally for organic milk production. This study evaluated the efficacy of a homeopathic preparation to control natural tick infestations. The evaluations were conducted with 24 taurine dairy cows during 12 months. The homeopathic medicine (30 CH + Sulfur 30 CH) was administered in a proportion of 1:100 (v/w) in a formulation with sugar, added to 30 kg of mineral salt. This preparation was supplied along with concentrated feed (2 kg/animal/day). The control group received the same feed mixture without the medicine. The groups were kept in separate paddocks. Data were collected on body weight, packed cell volume and number of engorged female ticks on each animal. Temperature, relative humidity and rainfall were recorded. Engorged females were collected from each group for in vitro comparison of reproductive parameters, and semi-engorged ticks for morpho-histological analysis. The mean results of body weight, packed cell volume and tick number were not statistically different between the control and treated groups: 616.5 kg and 618.6 kg; 27.9% and 27.3%; and 12.19 and 13.58 ticks, respectively. In the in vitro analyses, the average weights of the ticks (0.18 and 0.17 g) and eggs (0.07 and 0.06 g), larval hatching rate (70.1 and 76.6%) and reproductive efficiency index (54.3 and 60.6%) of the control and treated groups, respectively, also were not statistically different. Furthermore, no alteration in the ovaries was detected by microscopic analysis. Therefore, the homeopathic medicine was ineffective to control R. (B.) microplus, although the inclusion of agro-ecological practices might enhance its effect of homeopathy in controlling tick infestations.

Toxic action of Acmella oleracea extract on the male reproductive system of Amblyomma cajennense ticks.

The present study evaluated through morphohistological and histochemical techniques the effects of different concentrations of crude ethanolic extract of A. oleracea (EEAO) (Jambu) on the male reproductive system of Amblyomma cajennense sensu stricto (s.s.) ticks. The toxicity of this natural chemical was stablished, signalizing the promising potential of the compound as a strategy to control ectoparasites in the near future. For the experiment, 100 males fed on host rabbits with homogeneous weight (p>0.05) were used. The ticks were divided into five groups (10 animals each): Control 1-exposed to distilled water; Control 2-exposed to ethanol 50% and DMSO 1%; Treatment 1-3-exposed to the concentrations of 6.2, 12.5 and 25mg/mL of the EEAO, respectively, diluted in ethanol 50% and DMSO 1%, with exposure by immersion. After exposure, the males were dissected for the removal of the reproductive system and subjected to routine histological analysis with HE staining and histochemical techniques (PAS for the detection of neutral polysaccharides and Bromophenol blue to detect total proteins). The exposed individuals showed alterations in the glandular complex cells; however, the testes remained intact. The secretory cells of the multilobulated accessory glands presented intense cytoplasmic vacuolation. Additionally, the synthesis and secretion were reduced in the secretion granules, mainly concerning the polysaccharides, glyco- and lipoprotein elements, substances that will constitute the seminal fluid and enable the capacitation of spermatozoa in the female genital tract and also necessary for the formation of the spermatophore, which will encapsulate the mature spermatids. The alterations were dose-dependent, i.e., more intense and severe as the concentration of the product increased. .This experiment confirmed the cytotoxic potential of A. oleracea ethanolic extract in the concentrations of 6.2, 12.5 and 25mg/mL on the reproductive system of A. cajennense s.s. male ticks.

Deltamethrin as inductor agent of precocious ovarian degeneration in Rhipicephalus sanguineus s.l. (Acari: Ixodidae) ticks.

The cosmopolitan species Rhipicephalus sanguineus s.l. is one of the most widely distributed ticks all over the world. These ectoparasites are vectors of several pathogens and cause significant direct damage to their hosts. The biological success of these ectoparasites has been attributed to their ovaries and salivary glands, organs that ensure their survival in various environmental conditions. The importance of the ovaries in ticks is that, after mating, the individuals are able to lay approximately three thousand eggs. The present study had the objective to demonstrate the effects of deltamethrin obtained from the product Butox P CE 25® (MSD Saúde Animal, São Paulo, Brazil) on the ovarian development of R. sanguineus s.l. females. The chemical was tested in the concentrations of 25, 50, 100 and 200 ppm (respectively 80, 40, 20 and 10 times lower than the recommended by the manufacturer). Through the application of histological techniques and HE staining, the results showed that the deltamethrin was potentially able to modify the morphophysiology of the oocytes in all developmental stages, interfering in the vitellogenesis, causing intense vacuolation, cytoplasmic disorganization, and alterations in the chorion secretion. In addition, the chemical affected the germ vesicle of some oocytes, causing damages and hypertrophy, fragmenting the chromatin and forming bodies strongly stained by hematoxylin. Therefore, this study confirmed that the deltamethrin had an important action on the reproductive system of the R. sanguineus s.l. females, causing the precocious structural disorganization of the germ cells, consequently preventing the generation of new individuals.

Dinotefuran-induced morphophysiological changes in semi-engorged females Rhipicephalus sanguineus Latreille, 1806 (Acari: Ixodidae) ticks: Ultra-structural evaluation.

The present study demonstrated the effects of dinotefuran (active ingredient of the acaricide Protetor Pet®) on the ovary and midgut cells of semi engorged R. sanguineus females exposed to different concentrations of this chemical. For this, 120 semi-engorged females were divided into four treatment groups with 30 individuals each: group I or control (distilled water), group II (5000ppm), groups III (6250ppm) and group IV (8334ppm of dinotefuran). All the ticks were immersed in the different concentrations of dinotefuran or in distilled water for 5min and then dried and kept in BOD incubator for 7days. The results showed alterations mainly regarding the damaged cell structures, such as yolk granules, organelles and the plasma membrane of the germ cells. In addition, structures related with defense mechanisms were found, such as vacuoles, cytoskeletal filaments, and myelin figures in the germ cells. Damages in the generative cells of the midgut, alterations in the size of digestive cells, the number of endosomes, digestive vacuoles, digestive residues, lipid drops and organelles in the cytoplasm of the digestive cells and the presence of microvilli in the plasma membrane of these cells also demonstrate the progressive damages caused by the action of dinotefuran in the midgut and germ cells of R. sanguineus semi-engorged females. The concentrations applied partially impaired the digestive processes; and, without proper nutrition, all the ectoparasite's physiologic events are prevented from occurring, leading the individual to death. The germ cells were also damaged, and probably would not be able to advance in their development (I-V) and complete the vitellogenesis, which would affect the fertility of the female and consequently impede the formation of a new individual.

Potential action of extract of Acmella oleracea (L.) R.K. Jansen to control Amblyomma cajennense (Fabricius, 1787) (Acari: Ixodidae) ticks.

The use of synthetic acaricides is currently the main method to control ticks. However, the indiscriminate use of these chemicals can lead to the selection of resistant individuals and in the accumulation of chemical residues in the environment, contaminating the soil and water streams, consequently affecting the flora, fauna, and the human beings as well. In this sense, the objective of this study was to investigate the acaricidal effect of crude ethanolic extract of Acmella oleracea (L.) R.K. Jansen aerials parts at different concentrations on fed males and semi-engorged females of A. cajennense s.s. An in vitro bioassay (Adult Immersion Test) was carried out to determine the lethal concentration 50 (LC50) of ethanolic extract, calculated by Probit analysis. The results showed that the fed males were sensitive to all the concentrations of A. oleracea ethanolic extract, and mortality rate progressively increased (15-65%) in higher ethanolic extract concentrations. However, semi-engorged females were not sensitive to all the concentrations used here. In the highest concentration (100mg/mL), a mortality rate of 100% was observed after 72h of exposure, indicating that the acaricidal effect would probably be dose-dependent. The LC50 values obtained for the fed A. cajennense s.s males and semi-engorged females were 29.4534mg/mL (limits: 24.4467-41.3847mg/mL) and LC50=17.6335mg/mL (limits: 5.2506-23.5335mg/mL), respectively.

Acmella oleracea and Achyrocline satureioides as Sources of Natural Products in Topical Wound Care.

The Brazilian forests have one of the world's biggest biodiversities. Achyrocline satureioides (macela) and Acmella oleracea (jambu) are native species from Brazil with a huge therapeutic potential, with proved anti-inflammatory and anesthetic action, respectively. The jambu's crude extract after depigmentation with activated charcoal and macela's essential oil were incorporated in a film made with hydroxyethyl cellulose. Those films were evaluated by mechanical test using a texturometer and anti-inflammatory and anesthetic activities by in vivo tests: wound healing and antinociceptive. The film containing the highest concentration of depigmented jambu's extract and macela's essential oil obtained an anesthesia time of 83.6 (±28.5) min longer when compared with the positive control EMLA®; the same occurred with the wound healing test; the film containing the highest concentration had a higher wound contraction (62.0% ± 12.1) compared to the positive control allantoin and the histopathological analysis demonstrated that it increases collagen synthesis and epidermal thickening. The results demonstrate that the films have a potential use in skin wounds, pressure sore, and infected surgical wounds treatment.

Cytotoxic effects of extract of Acmella oleraceae (Jambú) in Rhipicephalus microplus females ticks.

The present study analyzed the effects of different concentrations of the hexane extract of A. oleraceae (HEAO) (Jambú) on the germ cells of semi-engorged Rhipicephalus microplus female ticks, through a morpho-histological study, evaluating the effectiveness of the extract in the genesis of the individuals. To perform this analysis, 100 semi-engorged females were divided into five groups with 20 individuals each: groups I and II, respectively constituted by distilled water control and 50% ethanol + 1% DMSO, and groups III, IV, and V constituted by treatment with HEAO in the concentrations of 12.5, 25.0 and 50.0 mg/mL, respectively. All the ticks were immersed in the different concentrations of the extract or in distilled water for 5 minutes, dried and conditioned in BOD incubator for 7 days. The individuals of the treatment groups revealed the action of this extract showing alterations in the germ cells of the females from the different groups when compared with those from the groups I and II (control groups). These alterations were mainly related to the size and shape of the oocytes; number of yolk granules; presence, number, size and location of vacuoles in the cytoplasm of all the germ cells; and the presence of nuclear alterations in these cells as well. Thus, it was demonstrated that the concentrations of HEAO affected the germ cells of R. microplus ticks. The effects of the extract are similar to those caused by renowned and efficient chemical products used to control these ticks. Microsc. Res. Tech. 79:744-753, 2016. © 2016 Wiley Periodicals, Inc.

Dinotefuran-induced morphophysiological changes in the ovaries and midgut of semi-engorged females Rhipicephalus sanguineus Latreille, 1806 (Acari: Ixodidae) ticks.

The present study demonstrated the effects of dinotefuran (active compound of the Protetor Pet® acaricide) in germ cells and the digestive processes of semi-engorged females of R. sanguineus exposed to different concentrations of the chemical. For this purpose, 120 semi-engorged females were divided into four treatment groups with 30 individuals each: group I or control (distilled water), group II (5000 ppm), group III (6250 ppm), and group IV (8334 ppm of dinotefuran). All ticks were immersed in different concentrations of dinotefuran or in distilled water for 5 min and then were dried and stored in biological oxygen demand (BOD) incubator for 7 days. The results show the action of this compound, exhibiting morphohistologic and histochemical changes in the oocytes and the midgut cells of individuals of different groups, which were compared with those of group I (control). The alterations occurred mainly in relation to the size of the germ cells and yolk granules; presence, quantity, size, and location of vacuoles found in the cytoplasm of these germ cells; the damage occurred in the generative cells of the midgut; the size of the digestive cells; the quantity of blood elements captured, accumulated digestive wastes and digestive vacuoles found in the cytoplasm of the digestive cells of the midgut, as well as the amount and distribution of proteins, polysaccharides, lipids of all cells in both organs. So, it has demonstrated the effectiveness of dinotefuran in the reduction of fertility and digestive processes of semi-engorged females of R. sanguineus, data that points the possibility of employing this chemical to control these ectoparasites.

Potential of the chemical dinotefuran in the control of Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) semi-engorged female ticks.

Ticks are vectors of several pathogens to vertebrates, including the human being. They produce lesions on the hosts during the blood feeding and great economic losses. Several chemical acaricides have been used in an attempt to control tick infestations; however these substances are harmful to both the human being and non-target organisms, and to the environment. Therefore, there is a need to fight these ectoparasites through less harmful methods, less aggressive to the environment, non-target organisms and to the human health. The present study examined the efficacy of dinotefuran on the susceptibility of Rhipicephalus sanguineus semi-engorged females exposed to different concentrations of the product. Its lethal concentration of 50% (LC50) at 95% confidence interval was determined. The ticks were immersed in Petri dishes containing different concentrations of dinotefuran or distilled water for 5 minutes and then dried and maintained in an incubator for 7 days. The results showed the daily number of dead R. sanguineus semi-engorged females after being treated with different concentrations of dinotefuran. The mortality data in bioassay 2 were subjected to Probit analysis, where a LC50 of 10,182.253 ppm (8725.987-13,440.084) and 95% confidence interval were estimated. The susceptibility of R. sanguineus semi-engorged females to dinotefuran in higher concentrations of the acaricide was demonstrated, indicating that its effect is probably dose-dependent. In addition, the action of dinotefuran was slow and gradual, interfering in the development and growth of the individuals throughout the observation period (7 days).

Morpho-histochemical characterization of the salivary glands of semi-engorged Amblyomma triste (Koch, 1844) (Acari: Ixodidae) female ticks.

This study presents the morphological and physiological characterization of the salivary glands of semi-engorged Amblyomma triste females. Unfed individuals were placed on New Zealand White rabbits for feeding and the females, after 4 days, were collected, dissected and the salivary glands were submitted to the application of histological (hematoxylin-eosin technique) and histochemical tests for the detection of protein (bromophenol blue technique, polysaccharides (periodic acid-Schiff technique), lipid (Nile blue technique) and calcium (von Kossa technique). The histological results show that the glandular tissue is composed by a system of ducts and three types of acini (I, II and III). The acini I are formed by a large central cell surrounded by several smaller agranular peripheral cells. Acini II are formed by cells a, c1, c2, c3 and c5, which are full of secretion granules. Acini III are constituted by cells d, e and f; the former two contain secretion granules, the latter is agranular. The glandular histochemical composition was also verified. Data obtained here will certainly help in the understanding of the cellular morphology and of the general physiology of these organs in this specie, providing important information for the creation of scientific bases which will contribute for the development of more specific and efficient methods of control.

Rhipicephalus sanguineus sensu lato (Acari: Ixodidae) nymphs: an ultrastructural study of the integument and midgut.

This is an ultrastructural study of two important organs of ticks: the integument, covering the body and involved in the molting process, and the midgut, the first organ to have contact with the ingested host blood. The integument of Rhipicephalus sanguineus sensu lato freshly engorged nymphs consists of a layer of epidermal cells rich in organelles and a cuticle, subdivided in epicuticle and procuticle. The latter presents two distinct regions: the exocuticle (with several pore canals) and the endocuticle (secreted in highly organized overlaid lamellae). The midgut of R. sanguineus sensu lato freshly engorged nymphs consists of an epithelial wall formed by two types of cells: the generative cells, with few organelles; and the digestive cells, with several endosomes, digestive vacuoles, hematin residual bodies, and small drops of lipid.