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Amblyomma sculptum is a common human-biting tick in Brazil, where it plays an important role as a vector of Rickettsia rickettsii, the agent of the Brazilian spotted fever. Herein, we studied the seasonal dynamics of A. sculptum in an urban area of the Cerrado biome in midwestern Brazil, where human rickettsiosis is endemic. Ticks were collected in two sites located within the campus of Federal University of Goiás. The collections were done by dragging, flagging and visual search. In total, 117,685 ticks were collected, including 100,627 Amblyomma spp. larvae, 10,055 nymphs and 6977 adults of A. sculptum, and one nymph and 25 adults of Amblyomma dubitatum. The highest peak of larvae occurred in June 2018 and in July 2019, whereas nymphs peaked in July 2018 and September 2019. Adults reached their highest numbers in March 2018 and November 2019. These data suggest that A. sculptum develops one generation per year in this urban area of the Cerrado biome in midwestern Brazil. Interestingly, the peak of nymphs occurred during the same period of all confirmed cases of rickettsiosis in Goiás, suggesting a possible relationship between the seasonal dynamics of this tick stage and rickettsiosis transmission in this state.

This study was carried out aiming to evaluate the repellent and acaricidal activity of major ingredient compounds from coconut oil including their methyl ester derivatives and catnip oil against nymphs and larvae of Amblyomma sculptum. Repellent candidates, coconut oil free fatty acids (coconut FFA mainly C12, C10 and C8 acid); lauric acid (C12 acid); capric acid (C10 acid); methyl laurate; methyl caprate and 10 % each of C12, C10 and C8 acid (1:1:1) in lavender oil formulation (CFA in lavender formula) and catnip oil (Nepeta cataria), were screened using a Petri dish bioassay to assess repellency. Catnip oil, methyl caprate, methyl laurate, and CFA in lavender formulation repelled ticks strongly (P

The present study aimed to evaluate the behaviour of larvae of Rhipicephalus microplus exposed to different stimuli. A Y-olfactometer was positioned vertically and R. microplus larvae were exposed to environmental air, CO2 alone, N,N-diethyl-3-methylbenzamide (DEET) alone, and CO2 combined with the repellents DEET and (E)-2-octenal. Tests were also conducted with the olfactometer positioned horizontally; in this case, however, only CO2 was tested. In all tests conducted with the Y-olfactometer positioned vertically, CO2 activated R. microplus larvae even in the presence of DEET and (E)-2-octenal, although activation was lower when these repellents were used. In the absence of CO2 , larval behaviour against DEET was similar to that of the larvae in the control group. In the tests performed with the olfactometer positioned horizontally, the larvae had no significant response to the presence of CO2 . The larvae were not attracted to or repelled by any compound tested in either the vertical or horizontal position of the olfactometer. The lack of horizontal displacement, attraction or repellence may have been a result of the ambush behaviour of this tick species. However, when larvae were exposed to stimuli and the olfactometer was positioned vertically, the interference of attractant and repellent stimuli in larval behaviour was assessed.

The present study aimed to develop a microemulsion formulation containing thymol and eugenol for field control of Rhipicephalus sanguineus sensu lato on dogs, as well to evaluate its safety and the physical characteristics of the formulation. The microemulsion using thymol and eugenol (5.0 + 5.0 mg/mL) had as vehicles water, propylene glycol, polysorbate 80 and canola oil. On the next day the preparation (formulation freshly prepared) and after 24 months, the size of the microemulsion droplets, polydispersion index (PdI), organoleptic properties (color, viscosity), and presence of precipitate in the microemulsion were evaluated. For the field assay, on day -1, 10 English Cocker Spaniel dogs were experimentally infested with 200 larvae, 100 nymphs and 30 adults of R. sanguineus s.l. On day 0, after tick counts, the animals were divided into two groups: treated with the freshly prepared microemulsion (10 mL/kg), and control, which received the vehicle (10 mL/kg). Tick counts on dogs were performed daily for three more days. Engorged females were recovered from the dogs and their biological and reproductive parameters were monitored. The dogs' clinical parameters (temperature, mucosa color, and general physical condition) were evaluated daily. In addition, blood samples were collected before infestation to verify hematological (packed cell volume) and biochemical parameters (total serum protein, albumin, globulins, creatinine, urea, alanine transaminase, aspartate aminotransferase, and alkaline phosphatase). Freshly prepared and 24-month aged microemulsions had droplets with mean sizes of 30.94 nm and 27.93 nm, and PdI values of 0.214 and 0.161, respectively. In addition, no difference in the organoleptic properties and no precipitation formation were observed, indicating physical stability. Treatment with the microemulsion resulted in reduction of larvae (p0.05) parasitizing the dogs on day 1 while the number of nymphs and adults was not reduced (P0.05). In the evaluation of the reproductive biology of engorged females, the larval hatchability (%) was compromised (p0.05), and the microemulsion had control rate of 85.5 %. The microemulsion and its vehicles did not change the clinical, hematological and biochemical parameters of the dogs. We concluded that the microemulsion was efficient against R. sanguineus s.l. by reducing the number of larvae and affecting the reproductive parameters of engorged females, safe for dogs, and stable (physical stability) during a two-year interval.

Benzaldehyde and 2-hexanone are allomones produced by beagle dogs that reduce infestation by Rhipicephalus sanguineus sensu lato on these animals and on susceptible dogs which artificially release these repellents. These observations were obtained in previous laboratory tests or artificial infestations of susceptible dogs under controlled conditions. Here we evaluated the efficacy of collars delivering these repellents for suppressing the loads of R. sanguineus s.l. on naturally infested mixed-breed dogs under field conditions. Thirty dogs naturally infested with R. sanguineus s.l. were separated into two groups with 15 dogs each. The dogs from the treatment group received the collars with slow-release formulations of the allomones, and the dogs from the control group received collars without such compounds. Collar effectiveness tests were carried out over 30 days. All ticks found were removed from each dog, identified, and counted every collection day. The density of the different life stages of R. sanguineus s.l. varied greatly between groups and across evaluation times. Adult ticks were the stage most abundant and prevalent on infested dogs. The counts for larvae, nymphs and adults were similar between the control and the treatment groups within each tick collection day. Conversely, when we considered the total number of ticks over 30 days and gathered all life stages collected in the same animal, the dogs from the control group had significantly higher loads (35.3 ± 4.27) of ticks than the dogs from the treatment group (21.8 ± 2.96) (P0.01). In addition, the efficacy of treatment with repellent collars was high for adult ticks (30.8%) but was extremely low for reducing larval or nymphal infestation (0 or 2.6%, respectively). The present study demonstrates, for the first time, the efficacy of these volatile compounds on naturally infested dogs under field conditions. The development of a technologically enhanced device for slow release of the allomones tested here can be an advantageous alternative for reducing R. sanguineus s.l. infestation on dogs in residential environments.

The present study evaluated over two years the seasonal dynamics of Rhipicephalus microplus in a Cerrado biome of midwestern Brazil (Goiânia, Goiás) and correlated the current climatic conditions (environmental temperature, insolation, rainfall, relative humitidy and saturation deficit of the atmosphere) of this site with 30 years ago. In addition, the data collected in the present research were compared with climatic conditions data and R. microplus population dynamics conducted by our group in other regions (Formiga, Minas Gerais and Jaboticabal, São Paulo) within the same biome. For the parasitic phase dynamics, R. microplus females (4.5-8.0 mm) counts were performed on tick natural infested cows kept in Panicum maximum paddocks. To verify the larvae dynamics on pasture the flannel dragg technique on natural infested pasture was performed, and the height of the grass was measured. Five peaks of engorged R. microplus females on animals and larvae infestations on pastures were observed. Being three and two peaks during the rainy and dry season of the year, respectively. Insolation (r = 0.8758; P = 0.00009; R² = 0.7670), rainfall (r = -0.8572; P = 0.0002; R² = 0.7348), maximum environmental temperature in summer (r = 0.9999; P 0.0087; R² = 0.9988) and the saturation deficit of the atmosphere in autumn (r = -0.9789; P = 0.0211; R² = 0.9582) influenced the seasonal dynamics of R. microplus larvae on pastures. While the forage height did not influence the number of larvae found on pasture (r = 0.1545; P = 0.7682; R² = 0.0239). The comparison between the climatic data of the last 30 years with the current climatological data (2012 to 2019) in the state of Goiás, and the comparison with R. microplus population dynamics from other two locations in the same biome indicated that the increase of the environmental temperature due to the global warming possibly is a determining factor which increase the number of one or up two tick annual peaks. In addition, this climatic variable was responsible for increase the population density of ticks on pastures and animals observed in July/winter of the present study, in comparison to other regions with the same biome, as discussed in this work.

Rhipicephalus sanguineus sensu lato and Amblyomma sculptum can parasite humans and domestic animals and are vectors of pathogens, including zoonoses. Repellents are an important tool of tick control. This study aimed to compare the efficacy of N,N-diethyl- 3-methylbenzamide (DEET), a standard repellent, versus β-citronellol in a Petri dish bioassay. A semicircle of filter paper (31.8cm2) was treated with 87μl of one of four concentrations (0.200, 0.100, 0.050 and 0.025mg/cm2) of β-citronellol, DEET or solvent (ethanol). A head-to-head test was developed treating one side with increasing concentrations of β-citronellol as above mentioned, against the highest concentration of DEET. Besides that a blank assay was performed. Three males and three females were placed in the middle of the plate and their location was evaluated 5, 10 and 30min after the test was initiated. As a result, the time had no significant effect on repellency response of the ticks exposed to both compounds and their concentrations. The repellency response raised according with the increase of concentration. Additionally, our findings indicate that the tick A. sculptum was more sensitive to the compounds tested and β-citronellol showed a higher efficacy than DEET. In addition, β-citronellol could be formulated to protect humans and other animals from R. sanguineus s. l. and A. sculptum infestation, as well as the diseases transmitted by these species.

Amblyomma sculptum is a tick affecting animal and human health across Argentina, Bolivia, Paraguay and Brazil. Donkeys, Equus asinus, are known to be resistant to A. sculptum, suggesting that they can produce non-host tick semiochemicals (allomones), as already demonstrated for some other vertebrate host/pest interactions, whereas horses, Equus caballus, are considered as susceptible hosts. In this study, we tested the hypothesis that donkeys produce natural repellents against A. sculptum, by collecting sebum from donkeys and horses, collecting the odour from sebum extracts, and identifying donkey-specific volatile compounds by gas chromatography (GC) and coupled GC-mass spectrometry (GC–MS). From the complex collected blends, five main compounds were identified in both species. Hexanal, heptanal and (E)-2-decenal were found predominantly in donkey extracts, whilst ethyl octanoate and ethyl decanoate were found predominantly in horse extracts. One compound, (E)-2-octenal, was detected exclusively in donkey extracts. In Y-tube olfactometer bioassays 36 different A. sculptum nymphs were tested for each extract, compound and concentration. The dry sebum extracts and the compounds identified in both species induced neither attraction nor repellency. Only (E)-2-octenal, the donkey-specific compound, displayed repellency, with more nymphs preferring the arm containing the solvent control when the compound was presented in the test arm across four concentrations tested (p

The species Cochliomyia hominivorax, also known as screwworm fly, is an obligate parasite of warm- blooded animals and its geographic range extends thoughout South America, except Chile. This fly causes significant economic losses and has great importance in Brazil. Few studies have focused on the excretion and secretion products of this species, and this research aimed to study the enzymes present in the secretion and excretion (E/S) products of the three larval instars of C. hominivorax. The E/S profile of proteins was obtained by polyacrylamide gel electrophoresis and proteolytic activity was analyzed using gelatin, azocasein and Na-benzoyl-arginine-nitroanilide as substrates. In E/S products of the three instars, proteins were detected with an apparent molecular weight ranging between 116 and 20 kDa. In the azocasein assay, at different pH ranges, the major proteolytic activity occurred at pH 7.5 for all larval instars. Assays were performed using the same substrates in which the samples were treated with the inhibitors Benzamidine, Pepstatin A, 4-(2-Aminoethyl) benzenesulfonyl fluoride hydrochloride (AEBSF), N-α-tosyl-L-lysine chloromethyl ketone (TLCK), N-α- tosyl-L-phenylalanine chloromethyl ketone (TPCK), Ethylenediamine tetraacetic acid (EDTA), and Leupeptin-trans-Epoxysuccinyl-leucylamido(4-guanidino) butane (E-64). Proteinases present in the E/S product of first larvae instar are mostly serine trypsin and chymotrypsin proteases, whereas for second and third instars serine proteases and aspartyl proteases were predominantly observed. Biochemical characterization of E/S products of all larval stages of C. hominivorax helps to improve the understanding of the physiology and the interaction of this parasite with host tissues. Keywords: Enzyme; fly; myiasis; parasites.

Proteomic analyses were done on 2 chemosensory appendages of the lone star tick, Amblyomma americanum. Proteins in the fore tarsi, which contain the olfactory Haller's organ, and in the palps, that include gustatory sensilla, were compared with proteins in the third tarsi. Also, male and female ticks were compared. Proteins were identified by sequence similarity to known proteins, and by 3-dimensional homology modeling. Proteomic data were also compared with organ-specific transcriptomes from the tick Rhipicephalus microplus. The fore tarsi express a lipocalin not found in the third tarsi or palps. The fore tarsi and palps abundantly express 2 proteins, which are similar to insect odorant-binding proteins (OBPs). Compared with insect OBPs, the tick OBP-like sequences lacked the cysteine absent in C-minus OBPs, and 1 tick OBP-like sequence had additional cysteines that were similar to C-plus OBPs. Four proteins similar to the antibiotic protein microplusin were found: 2 exclusively expressed in the fore tarsi and 1 exclusively expressed in the palps. These proteins lack the microplusin copper-binding site, but they are modeled to have a significant internal cavity, potentially a ligand-binding site. Proteins similar to the dust mite allergens Der p7 and Der f 7 were found differentially expressed in female fore tarsi. A protein exclusively expressed in the fore tarsi has similarities to Neto, which is known to be involved in clustering of ionotropic glutamate receptors. These results constitute the first report of OBP-like protein sequences in ticks and point to several research avenues on tick chemosensory reception.

The present study was conducted to elucidate the neuronal pathways between peripheral olfactory and taste sensilla and the synganglion in an Ixodidae tick species. The tarsus of the front legs (olfactory nerves) and the fourth palpal segment (gustatory nerves) of unfed Amblyomma americanum males and females were excised. A neuronal tracer, dextran tetramethylrhodamine, was used for filling of the sensory neurons. The synganglion preparations were examined using a confocal microscope. Neuronal arborizations from the Haller’s organ were confined to the olfactory lobes and the first pedal ganglion. The estimated number of olfactory glomeruli ranged from 16 to 22 per olfactory lobe in the females. The number of glomeruli was not counted in males because they were densely packed. Sensory neurons associated with sensilla at the distal end of the palpal organ projected into the palpal ganglion in the synganglion through the palpal nerve. Gustatory sensory neurons associated with palpal sensilla projected into a commissure with several bulges, which are confined in the palpal ganglion. The findings of distinct projection patterns of sensory neurons associated with the Haller’s organ and palpal organ in the lone star tick from this study advanced our knowledge on mechanisms of sensory information processing in ticks. Resumo O presente estudo foi conduzido para elucidar a trajetória neuronal, entre as sensilas periféricas olfativas e gustativas e o singânglio, em uma espécie de carrapato Ixodidae. O tarso da primeira pata (nervos olfativos) e o quarto segmento palpal (nervos gustativos) de machos e fêmeas não alimentados de Amblyomma americanum foram excisados. Um traçador neuronal, dextran tetrametilrodamina, foi usado para preenchimento dos neurônios sensoriais. Os singânglios foram examinados através de microscopia confocal. Arborizações neuronais do órgão de Haller foram confinadas nos lobos olfativos e primeiro gânglio pedal. O número estimado de glomérulos olfativos variou de 16 a 22 por lobo olfativo nas fêmeas. Em machos, o número de glomérulos não foi contado, pois eles estavam densamente compactados. Os neurônios sensoriais associados com as sensilas, na porção distal do órgão palpal, projetaram-se no gânglio palpal do singânglio através do nervo palpal. Neurônios sensoriais gustativos associados com a sensila palpal projetaram-se numa comissura onde havia vários bulbos. Os resultados obtidos neste estudo de padrões de projeção distintos de neurônios sensoriais associados com os órgãos de Haller e palpal no carrapato A. americanum avançam nosso conhecimento sobre os mecanismos de processamento da informação sensorial em carrapatos.

We evaluated the effects of 3β-O-tigloylmelianol from Guarea kunthiana A. Juss (Meliaceae) on oogenesis, as a larvicide and on ecdysis of the larvae and the nymphs of the cattle tick Rhipicephalus (Boophilus) microplus (Canestrini) (Acari: Ixodidae). On the oogenesis' test, 48 engorged females were divided into three groups, evaluated at 24, 48 and 72 h post-treatment. Half of the females were treated with 0.01% 3β-O-tigloylmelianol diluted in distilled water and 5% dimethyl sulfoxide (DMSO), while the other half (controls) were exposed to distilled water and 5% DMSO. After treatment, the ovaries were weighed in order to measure the gonadosomatic index (GSI) and were also subjected to standard histological technical tests. On the larvicide and ecdysis' tests, 3β-O-tigloylmelianol was tested at concentrations of 0.01, 0.005, 0.0025 and 0.00125%. Compared with the controls, there was a reduction of GSI of approximately 50% on the treated group, which started at 48 h post treatment. Overall, the protolimonoid 3β-O-tigloylmelianol has caused a significant reduction in the number of oocytes. It has also caused alteration of the cytoplasmic and germinal vesicle diameters. Morphological changes, such as vacuolization, chorion irregularity which has modified the oocytes' morphology as well as alterations on the yolk's granules were also observed. The compound was not larvicide, however, interfered in the ecdysis of the larvae and the nymphs. This study shows that the protolimonoid 3β-O-tigloylmelianol from G. kunthiana acts on oogenesis and ecdysis of R. (B.) microplus, but not as larvicide, indicating that it acts on the endocrine system of the tick.

The aim of this study was to investigate whether the combination of thymol with eugenol has a synergistic effect on the immature life stages of Rhipicephalus sanguineus sensu lato (s.l.), to evaluate the cost-benefit ratio of using these compounds in combination, and to develop a formulation combining thymol with eugenol with activity on immature stages of R. sanguineus s.l. To evaluate synergism, thymol and eugenol, combined (ratio 1:1) or not, were tested at concentrations of 2.5, 5.0, 10.0, 15.0 and 20.0 mg/mL on unfed larvae and nymphs using a larval packet test, and 0.625, 1.25, 2.5, 5.0 and 10 mg/mL on engorged larvae and nymphs using an immersion test. A cost estimate was calculated to produce 1 L of a solution containing a concentration of thymol and eugenol, combined or not, that could cause a tick mortality rate greater than 95 %. Finally, a formulation was developed, consisting of a micellar dispersion containing polymers (MDP), with thymol + eugenol (1:1), at concentrations of 2.5, 5.0, 10.0, 15.0 and 20.0 mg/mL, and the activity was evaluated on unfed and engorged larvae and nymphs. For unfed larvae and nymphs, concentrations of 2.5 and 5.0 mg/mL and 2.5, 5.0 and 10.0 mg/mL, respectively, presented synergistic effects. In tests with engorged larvae and nymphs, respective concentrations of 0.625, 1.25 and 2.5 mg/mL and 2.5 and 5.0 mg/mL had synergistic effects. The estimated costs for producing a solution of 1 L with efficacy greater than 95 % was $5.97 using only thymol (15 mg/mL), $ 5.93 using only eugenol (15 mg/mL), and $ 3.97 using thymol + eugenol (1:1 - 5,0 mg/mL). In tests with MDP, the combination of thymol + eugenol resulted in a mortality rate higher than 95 % at concentration of 10 mg/mL for unfed and engorged larvae and nymphs. Thus, the combination of thymol + eugenol, depending on the concentration, has synergistic effects and this combination lowers the cost for the active ingredients thymol and eugenol. The combination of thymol + eugenol in MDP had acaricidal activity against immature life stages of R. sanguineus s.l.

Lipids extracted from the surface of the lone star tick, Amblyomma americanum, were analyzed by high resolution mass spectrometry. Prior to lipid extraction, the adult ticks were either unfed or fed on cattle, and the fed ticks were in groups either containing males and females together, or containing only males or females. Cholesteryl esters were found on the surfaces of fed females, and they may provide a more complete description of the composition of the mounting sex pheromone. Dihydrocholesteryl esters were detected on the surfaces of unfed males and females, suggesting a possible role in survival during host-seeking. Dehydrodeoxyecdysone, found on fed females, could be a component of the genital sex pheromone. The most abundant polar surface lipids detected were acylglycerides. High levels of sphingolipids and glycerophospholipids on males fed separately might be derived, in part, from sperm development. A high level of a 20:4 fatty acid, presumably arachidonic acid, was found on the surface of fed females, indicating that it may be a component of the genital sex pheromone. A high level of docosenamide was found on the surface of fed females. Wax esters were found on the surfaces of fed ticks but not on unfed ticks. These esters could be involved in elasticity of the cuticle of engorged females or in wax coating of eggs. N-acylethanolamines were found on the surfaces of male and female ticks fed together, and on male ticks fed separately, but were absent or at low levels on females fed separately and on unfed ticks. This pattern suggests a possible role as a metabolic coordination primer pheromone.

Beagles are less susceptible to Rhipicephalus sanguineus sensu lato tick due to the production of the allomones benzaldehyde and 2-hexanone. Our previous published work showed that these compounds can reduce tick burden on susceptible dogs. Here we tested the hypothesis that an increase in repellent dose and release rate could increase repellent efficacy and persistence. Slow-release formulations of these compounds, with higher doses and release rates, were tested on artificially-infested dogs. Ten dogs were randomly assigned to two groups with five dogs each. The treated group received collars with slow-release formulations of the compounds attached, while the control group received collars with clean formulations attached. Five environmental infestations were performed, with the number of ticks (at all stages) on the dogs being counted once a day for 40 days. No significant increase in repellent efficacy was observed with the higher doses and release rates, whereas a greater persistence in repellent activity was observed. Treatment with the formulations resulted in a two-to-three-fold reduction in the number of immature stage ticks for up to three weeks. However, the number of adults was similar in both groups. Loss of repellent activity after the third week of testing coincided with a marked change in the relative release rates for the two compounds. It is hypothesized that relative amounts, rather than absolute amounts, of repellent release from slow-release formulations are important for repellent activity. We also hypothesize that the avoidance of less-preferred hosts by ticks relies on olfactory-mediated perception of specific blends of volatile cues from less preferred hosts. Resumo Beagles são menos suscetíveis ao carrapato Rhipicephalus sanguineus sensu lato devido à produção de benzaldeído e 2-hexanona. Nosso trabalho anterior já publicado mostrou que esses compostos podem reduzir a carga de carrapatos em cães suscetíveis. Aqui testamos a hipótese de que um aumento na dose destes repelentes e na taxa de liberação poderia aumentar a eficácia e a persistência do efeito repelente. As formulações de liberação lenta destes compostos, com doses e taxas de liberação mais elevadas foram testadas em cães infestados artificialmente. Dez cães foram distribuídos aleatoriamente em dois grupos com cinco cães cada. O grupo tratado recebeu colares contendo formulações de liberação lenta dos compostos, enquanto o grupo controle recebeu colares com formulações limpas. Cinco infestações ambientais foram realizadas, com o número de carrapatos (em todas as fases) nos cães sendo contados, uma vez ao dia, por 40 dias. Não se observou aumento significativo na eficácia do repelente com doses e taxas de liberação mais elevadas e, enquanto observou-se maior persistência na atividade repelente. O tratamento com as formulações resultou em uma redução de duas a três vezes no número de carrapatos dos estágios imaturos, por até três semanas. No entanto, o número de adultos foi semelhante em ambos os grupos. A perda de atividade repelente após a terceira semana de teste coincidiu com uma mudança nas taxas de liberação relativa para os dois compostos. A hipótese é que as quantidades relativas, ao invés das quantidades absolutas de liberação lenta, são importantes para a atividade repelente. Então, a hipótese é de que a repelência apresentada por hospedeiros menos susceptíveis aos carrapatos depende da percepção pelos carrapatos de misturas específicas de voláteis liberados por estes hospedeiros.

Hematophagous arthropods are capable of transmitting human and animal pathogens worldwide. Vector-borne diseases account for 17% of all infectious diseases resulting in 700,000 human deaths annually. Repellents are a primary tool for reducing the impact of biting arthropods on humans and animals. N,N-Diethyl-meta-toluamide (DEET), the most effective and long-lasting repellent currently available commercially, has long been considered the gold standard in insect repellents, but with reported human health issues, particularly for infants and pregnant women. In the present study, we report fatty acids derived from coconut oil which are novel, inexpensive and highly efficacious repellant compounds. These coconut fatty acids are active against a broad array of blood-sucking arthropods including biting flies, ticks, bed bugs and mosquitoes. The medium-chain length fatty acids from C8:0 to C12:0 were found to exhibit the predominant repellent activity. In laboratory bioassays, these fatty acids repelled biting flies and bed bugs for two weeks after application, and ticks for one week. Repellency was stronger and with longer residual activity than that of DEET. In addition, repellency was also found against mosquitoes. An aqueous starch-based formulation containing natural coconut fatty acids was also prepared and shown to protect pastured cattle from biting flies up to 96-hours in the hot summer, which, to our knowledge, is the longest protection provided by a natural repellent product studied to date.

The control of Rhipicephalus microplus (Ixodida: Ixodidae) is achieved using synthetic acaricides. However, resistant tick populations are widespread around the world. Plant essential oils can act as repellents, keeping ticks away from hosts and decreasing the selection pressure on synthetic acaricides. The aim of this study was to evaluate the in vitro repellent effect of Lippia alba essential oil on R. microplus larvae. Leaves from two L. alba genotypes maintained under the same agronomic and environmental conditions were collected. Essential oil was extracted by hydrodistillation and analysed by gas chromatography-mass spectrometry (GC-MS). The major monoterpenes detected in the chemical analysis were commercially acquired and tested. For the repellency test, a glass rod was vertically fixed to measure active climbing of approximately 30 R. microplus larvae aged 14-21 days in response to essential oils and monoterpenes. Repellency was evaluated at 1 h, 3 h and 5 h after treatment. Variation in repellent action was detected between the genotypes. The major monoterpenes identified in the essential oils (limonene and carvone) showed low repellent effects in comparison with intact essential oils. Thus, the present results showed that L. alba essential oil contains bioactive compounds with great repellent activity against ticks that varies according to the plant genotype.

Rhipicephalus microplus is considered the most economically important ectoparasite of cattle worldwide. It is known that zebuine breeds of cattle are less susceptible to tick infestation than taurine breeds. Contact chemoreceptors in the cheliceral pit sensilla of ticks respond selectively to phagostimulant compounds, however their role in blood feeding relative to host susceptibility to infestation remains to be fully understood. We addressed this topic by conducting taste electrophysiology experiments with cheliceral pit sensilla preparations of R. microplus females. Solutions of five known ixodid tick phagostimulants were tested at different concentrations: sodium (NaCl), and potassium chloride (KCl) (10(-3)-10(-1)M); glucose (10(-4)-10(-1)M); adenosine triphosphate (ATP) (10(-6)-10(-2)M); and reduced l-glutathione (GSH) (10(-6)-10(-2)M). Serum samples from six susceptible animals of the Girolando breed (5/8 Bos indicus×3/8 B. taurus) and six resistant Nelore bovines (pure B. indicus) were also tested. A dose-dependent response of gustatory neurons associated with the chelicerae sensillum to NaCl, glucose, GSH, and ATP were observed. Responses by the cheliceral inner digit pit sensilla of R. microplus to KCl and glucose were also observed and they are reported here for the first time. In addition to an electrophysiological response to known phagostimulants, chemoreceptors in the chelicera of R. microplus responded differently to serum from cattle susceptible and resistant to infestation. The cheliceral pit neurons were more responsive to serum of R. microplus resistant bovines with a higher mean spike frequency (53.5±2spikess(-1)) than to serum samples from susceptible cattle (40.3±2spikess(-1)). The implications of chemosensation during tick blood feeding are discussed.

Embora Rhipicephalus microplus parasite principalmente bovinos, diferentes racas podem ter cargas parasitarias variaveis, sendo os bovinos indianos menos suscetiveis a esse carrapato que os bovinos europeus. Este carrapato usa um comportamento de procura conhecido como questing para encontrar seu hospedeiro nas pastagens. Utilizando um teste em olfatometro, onde a larva podia expressar o questing, objetivou-se responder se a larva podia expressar diferentes comportamentos dependendo da raca de bovino envolvida. Dezesseis larvas foram expostas para os odores de cinco bovinos holandeses, cinco nelores, hexano (controle negativo) e 2-nitrofenol (controle positivo). As mais altas respostas foram observadas para o 2-nitrofenol e odor de holandes. A mais baixa resposta foi observada para o solvente e foi estatisticamente similar ao odor de nelore. E possivel concluir que R. microplus expressa de forma diferente o comportamento de questing dependendo do odor da raca de bovinos percebido. Esse comportamento pode ajudar R. microplus a evitar parasitar bovinos nelore, o que e biologicamente vantajoso para o carrapato, uma vez que se sabe que carrapatos alimentados neste hospedeiro tem seu desenvolvimento comprometido

Hexane extract of chinaberry, Melia azedarach L., unripe fruits obtained from different municipalities of Goiás State, Brazil, were evaluated on the southern cattle tick, Rhipicephalus (Boophilus) microplus (Canestrini), engorged females. Hexanic extracts were assayed in decreasing concentrations from 0.25 to 0.0156% to determine effects on egg production and hatching. Efficacy on engorged females decreased as a result of the extracts from Goiânia (100%), Professor Jamil (97.5 ± 3.0%), Pirenópolis (95.1 ± 2.4%), Morrinhos (86.8 ± 9.4%), Caturaí (41.8 ± 29.3%), and Bela Vista de Goiás (17.1 ± 0.9%) municipalities. Canonical redundancy analysis indicated that the extract bioactivity was positively correlated with soil Ca2+, Mg2+, and P and negatively correlated with silt, K+, potential acidity, and organic matter. This study demonstrates that M. azedarach hexanic extract can dramatically reduce R. (B.) microplus reproductive capacity and that efficacy is strongly influenced by differences in soil constituents between collection sites.

This study had the objective of determining the species of parasitoids of Diptera from May 2003 to June 2004 in the Region Southern and from March 2012 to February 2013 in the Region Central of (Goiania) Goias, Brazil. The dipterous pupae were obtained by the flotation method. They were individually placed in gelatin capsules until the emergence of the flies and/or their parasitoids. The percentage of parasitism in the Region South was 12.4% and in the Region Central was 6.4%. The species more frequent were: Gnathopleura quadridentata Wharton, 1986 (Hymenoptera: Braconidae) with 25.6% in the Region Southern and Aleochara notula Erichson, 1839 (Coleoptera: Staphylinidae) with 26.1% in the Region Central.

A total of 73 ethanol extracts from different anatomical parts of 44 plant species belonging to 24 families, native to the Mid-Western region of Brazil, were assessed in vitro for their effect on the reproductive cycle of engorged females of the cattle tick Rhipicephalus (Boophilus) microplus, using the adult immersion test. All extracts were evaluated at the concentration of 0.2 % and, among the extracts tested, the one obtained from the fruits of Guarea kunthiana (Meliaceae) proved to be highly efficacious, showing 99.1 % of product effectiveness. Extracts from other three species were shown to be moderately active, namely Nymphaea amazonum trunk (Nymphaeaceae) [51.7 %], Strychnos pseudoquina trunk (Loganiaceae) [8.0 %] and Ocotea lancifolia leaves (Lauraceae) [34.5 %], while the remaining extracts were shown to be weakly active or inactive. This is the first report on the bioactivity of these species on egg production by engorged females of R. microplus.

In the present study, host-related and tick pheromone-related chemical compounds were tested by means of the tip-recording technique in order to obtain electrophysiological responses in olfactory sensilla of non-fed Amblyomma cajennense ticks. The following chemicals were tested on the multiporose sensilla DI.1, located anterior to Haller's organ, and the sensillum DII.1, in the anterior pit of this organ: isobutyric acid, butyric acid, valeric acid, trans-2-heptenal, heptanal, benzaldehyde, salicylaldehyde, nonanal, m-, o- and p-tolualdehyde, 2-furaldehyde, 3-pentanone, γ-valerolactone and 1-octen-3-ol (which are all vertebrate-associated volatiles); and 2,6-dichlorophenol (2,6-DCP), 2-nitrophenol, methyl salicylate and nonanoic acid (tick pheromone components). These were used at 10−3 M and 10−2 M on at least 10 ticks per substance, and the chemicals that were found to be active at these concentrations were then tested as a series from 10−6 M to 10−2 M, in decadic steps, on at least 15 ticks per substance. 2,6-DCP was active on both sensilla, with detection thresholds of 10−6 M on the DI.1 sensillum and 10−4 M on the DII.1 sensillum. The olfactory neurons of this sensillum also responded to nonanal at the highest concentration used (10−2 M), while those of DII.1 responded not only to 2.6 DCP but also to 2-nitrophenol (to the same extent as to 2,6-DCP) and to 1-octen-3-ol. These results confirm the importance of 2,6-DCP in the chemical ecology of A. cajennense and indicate other compounds that may interfere with the behavior of this tick and which should be investigated.

This study was developed aiming to evaluate the acute effects of Melia azedarach hexanic fruit extract on mice. Two treated groups, one for each dose, 300 mg/kg and 2000 mg/kg, were prepared. For each treatment group, a non-treated control group was used. All groups were composed of six animals, three of each sex. The animals were evaluated at 30 min., 1h, 2h, 4h, 6h, 12h and 24h and then daily, for 14 days after treatment, following the Hippocratic screening. At each three days weight gain and ration consumption were evaluated. Macroscopic and microscopic alterations were evaluated in the heart, kidneys, lungs, liver, spleen, intestine and brain. No alteration in the Hippocratic screening in both doses, during the 14-days interval, was observed. The mice treated with the 2000 mg/kg doses consumed fewer rations than the animals of the control group; however, weight gain was statistically similar. No statistic difference was observed between the weight of the organs, and they had no macroscopic alterations. No histopathologic alterations were found on the examined organs, for both doses, except for lung alterations such as hyperaemia, haemorrage and edema in both treated and control groups. Based on the results obtained, we conclude that the hexanic extract of M. azedarach green fruits had no acute effects against Swiss mice. KEYWORDS: acute effects; hexanic extract of green fruits; histopathology; Melia azedarach ; Swiss mice.

Domestic dog breeds are hosts for the brown dog tick, Rhipicephalus sanguineus sensu lato, but infestation levels vary among breeds. Beagles are less susceptible to tick infestations than English cocker spaniels due to enhanced production of 2-hexanone and benzaldehyde that act as volatile tick repellents. We report the use of prototype slow-release formulations of these compounds to reduce the burden of R. sanguineus s. l. on English cocker spaniel dogs. Twelve dogs were randomly assigned to two groups with six dogs each. The treated group received collars with slow-release formulations of the compounds attached, while the control group received collars with clean formulations attached. Five environmental infestations were performed, with the number of ticks (at all stages) on the dogs being counted twice a day for 45 days. The counts on the number of tick stages found per dog were individually fitted to linear mixed effects models with repeated measures and normal distribution for errors. The mean tick infestation in the treated group was significantly lower than in the control group. For larvae and nymphs, a decrease in tick infestation was observed at the fifth count, and for adults, lower average counts were observed in all counts. The compounds did not interfere with the distribution of the ticks on the body of the dogs, as a similar percentage of ticks was found on the anterior half of the dogs (54.5% for the control group and 56.2% for the treated group). The biological and reproductive parameters of the ticks were not affected by the repellents. This study highlights for the first time the potential use of a novel allomone (repellent)-based formulation for reduction of tick infestation on susceptible dogs.

The extract from fed Amblyomma cajennense (Fabricius) males was characterized for chemical composition and behavioural responses. The pheromone was obtained by extraction in hexane, analysed by gas chromatography/mass spectrometry-single ion monitoring and subjected to behavioural bioassays in vitro and in vivo. The presence of 10 constituents already identified in tick pheromones was evaluated and qualitative analysis of the extract indicated the presence of benzaldehyde, benzoic acid, nonanoic acid, salicylic acid, 2,6-dichlorophenol, limonene and methyl salicylate and the absence of butyric acid, isobutyric acid and o-nitrophenol. In an olfactometer bioassay, males, females and nymphs were not attracted by the extract (P > 0.05) as the displacement angles (0°–10°) distribution was similar between tests (13.3–38.6%) and controls (8.5–23.7%). Similarly, there was no statistically significant aggregation response of test ticks to extracts in bioassays in vitro. However, significantly greater attachment (P...

We have recently shown that repellency of the tick Rhipicephalus sanguineus sensu lato by the tick resistant dog breed, the beagle, is mediated by volatile organic compounds (VOCs) 2-hexanone and benzaldehyde present in beagle odour. Ectoparasite location of animal hosts is affected by variation in these odour components and their ratios. The aim of this study was to quantify the release rate, and the ratio, of 2-hexanone and benzaldehyde from beagles. The odour of three beagles was collected, for four days, over one week (day 0, day 1, day 4 and day 7). The compounds were identified using coupled high-resolution gas chromatography-mass spectrometry (GC-MS), and authentic standards of compounds were used to generate external calibration curves for quantification. Both compounds were found in all dogs on all days. The amount of benzaldehyde was always higher than that of 2-hexanone and so their ratio varied from unity, on average (over time) being 3.128±0.365, 1.902±0.390, 1.670±0.671ngmL(-1) for beagle 1, 2 and 3, respectively. There was no significant (p0.05, F-test) effect of time. The overall mean was 2.233±0.387ngmL(-1). These results further previous findings by documenting the presence of 2-hexanone and benzaldehyde in beagle odour samples covering a 7-day period. This knowledge enables development of repellents to protect dogs from R. sanguineus s. l. infestation.

In order to clarify the role of 2,6-dichlorophenol (2,6-DCP) in the courtship of Amblyomma cajennense, sexually mature males that had previously fed on rabbits were tested in bioassays. The males were released onto dummies treated with whole female extract or synthetic 2,6-DCP at a concentration of two female equivalents, or with hexane (control), and their responses were observed. In the presence of both the extract and 2,6-DCP, excitation was observed among the males, expressed in the form of touching and probing the dummy, and mounting occurred readily. The percentages of mounting (73%) and tipping over (60%) were equal in the two treatments and higher than in the control group (27 and 20%, respectively). Relatively short durations of mounting were recorded, and these were statistically similar in all treatments. Almost all instances of mounting resulted in tipping-over behavior. A few isolated cases of males that went directly to ventral positioning without mounting were observed. It was confirmed that 2,6-DCP alone is capable of mediation of mounting behavior in A. cajennense.Visando elucidar o papel do 2,6-diclorofenol (2,6-DCF) no cortejo de Amblyomma cajennense, machos sexualmente maduros, previamente alimentados em coelhos, foram avaliados em testes biológicos. Os machos foram liberados sobre manequins tratados com um extrato de fêmeas, ou com 2,6-DCF sintético na concentração equivalente a duas fêmeas, ou com hexano (controle), e suas respostas foram observadas. Na presença do extrato e do 2,6-DCF, a excitação dos machos foi expressa na forma de toques e sondagens, e a monta ocorreu rapidamente. As porcentagens de respostas observadas nos dois tratamentos foram iguais, sendo a monta (73%) e retorno na superfície ventral (60%) mais altos que no controle (27 e 20%, respectivamente). Foram observados períodos de monta relativamente curtos, sendo esses estatisticamente iguais em todos os tratamentos, e quase todos resultando em posicionamento ventral. Alguns casos isolados de posicionamento ventral sem monta foram observados. Foi confirmado que o 2,6-DCP sozinho é capaz de mediar o comportamento de monta de A. cajennense.

The evolution of resistance of Rhipicephalus (Boophilus) microplus to synthetic acaricides has given rise to the need for new scientific investigations on alternative ways to control this tick. In this regard, various studies on plants have been developed in an attempt to find extracts with acaricidal properties. Evaluations on plant extracts for controlling R. (B.) microplus have grown intensely over the last decade. There are many advantages from using plant extracts: for example, they can be used in organic cattle farming or even replace synthetic acaricides and they are associated with lower environmental and food contamination, slower development of resistance and lower toxicity to animals and humans. In vitro studies on plant extracts have shown promising results, but most of these extracts have not been tested on animals to validate their use. Difficulties in preparing proper formulations, differences in the chemical composition of plants of the same species due to extrinsic and intrinsic factors and sparse information on active acaricide compounds are hindrances that need to be addressed in order to enable progress within this scientific field. A evolução da resistência do Rhipicephalus (Boophilus) microplus aos acaricidas sintéticos tem impulsionado novas investigações científicas sobre métodos alternativos para controlar este carrapato. Considerando isso, vários estudos com plantas têm sido desenvolvidos numa tentativa de encontrar extratos com propriedades acaricidas. Avalições de extratos de plantas para o controle de R. (B.) microplus tem sido intensificadas nesta última década. Existem muitas vantagens com o uso de extratos de plantas no controle deste carrapato, como: eles podem ser utilizados na produção orgânica de bovinos, ou mesmo substituir os acaricidas sintéticos, além do mais, estão associados com baixa contaminação ambiental e dos alimentos, desenvolvimento mais lento de resistência e baixa toxicidade para animais e seres humanos. Estudos in vitro de extratos de plantas têm apresentado resultados promissores, mas a maioria destes extratos não têm sido testada em animais para validar estes resultados. Dificuldades para preparar formulações apropriadas, diferenças na composição química de plantas de uma mesma espécie devido a fatores intrínsecos e extrínsecos e informações esparsas.sobre os princípios ativos são entraves que precisam ser solucionados visando o desenvolvimento deste campo de pesquisa.

The evolution of resistance of Rhipicephalus (Boophilus) microplus to synthetic acaricides has given rise to the need for new scientific investigations on alternative ways to control this tick. In this regard, various studies on plants have been developed in an attempt to find extracts with acaricidal properties. Evaluations on plant extracts for controlling R. (B.) microplus have grown intensely over the last decade. There are many advantages from using plant extracts: for example, they can be used in organic cattle farming or even replace synthetic acaricides and they are associated with lower environmental and food contamination, slower development of resistance and lower toxicity to animals and humans. In vitro studies on plant extracts have shown promising results, but most of these extracts have not been tested on animals to validate their use. Difficulties in preparing proper formulations, differences in the chemical composition of plants of the same species due to extrinsic and intrinsic factors and sparse information on active acaricide compounds are hindrances that need to be addressed in order to enable progress within this scientific field.A evolução da resistência do Rhipicephalus (Boophilus) microplus aos acaricidas sintéticos tem impulsionado novas investigações científicas sobre métodos alternativos para controlar este carrapato. Considerando isso, vários estudos com plantas têm sido desenvolvidos numa tentativa de encontrar extratos com propriedades acaricidas. Avalições de extratos de plantas para o controle de R. (B.) microplus tem sido intensificadas nesta última década. Existem muitas vantagens com o uso de extratos de plantas no controle deste carrapato, como: eles podem ser utilizados na produção orgânica de bovinos, ou mesmo substituir os acaricidas sintéticos, além do mais, estão associados com baixa contaminação ambiental e dos alimentos, desenvolvimento mais lento de resistência e baixa toxicidade para animais e seres humanos. Estudos in vitro de extratos de plantas têm apresentado resultados promissores, mas a maioria destes extratos não têm sido testada em animais para validar estes resultados. Dificuldades para preparar formulações apropriadas, diferenças na composição química de plantas de uma mesma espécie devido a fatores intrínsecos e extrínsecos e informações esparsas.sobre os princípios ativos são entraves que precisam ser solucionados visando o desenvolvimento deste campo de pesquisa.

The use of a concentrate emulsion of Melia azedarach green fruits and a suspension of the fungus Beauveria bassiana was evaluated in the control of Rhipicephalus microplus on artificially infested cattle. The evaluation was conducted following the protocol established by the Brazilian Agriculture Ministry. Five groups of 4 or 5 animals were allocated to one of the following treatments: emulsion concentrate of M. azedarach at 0.25% (T AZED 0.25%), emulsion concentrate of M. azedarach at 0.5% (T AZED 0.5%), B. bassiana at 2.4 × 10 8 conidia (T BASS), association of the concentrate of M. azedarach at 0.25% with B. bassiana at 2.4 × 10 8 conidia (T AZED 0.25% + BASS), and control (untreated). The association of the two compounds provided better results than any one isolated treatment, indicating compatibility or perhaps a synergy between M. azedarach and B. bassiana . This treatment resulted in fewer engorged females (129 ± 70) than in the control group (233 ± 82), showing high performance against all developmental stages of the tick. Results revealed an apparent synergistic effect of M. azedarach and B. bassiana in the control of R. microplus that should be further investigated.

Neosporosis is considered to be one of the main causes of abortions in bovines. In this study we evaluated the congenital transmission and occurrence of abortions by Neospora caninum in an embryo transfer center in Neropolis, Goiás. Serological samples from 101 recipients, 61 donors, and 90 calves were analyzed. Among these animals, 32.67% of the recipients, 22.22% of the donors, and 6.66% of the calves were positive for N. caninum. The rate of vertical transmission was 24%. There was a statistically significant difference between antibody titer of the recipient cows and the serological status of the calves. There was no statistically significant relationship between N. caninum serological status and reproductive rates such as estrum repetition and embryo production. Eight abortions occurred, six (75%) in positive females and two (25%) in negative females. These results indicate that neosporosis may be an important cause of failing reproduction and that in embryo transfer centers recipients should be previously examined, and those that are seronegative for Neospora should be chosen to reduce abortion and the birth of seropositive calves.

The aim was to describe epidemiological, clinical and histological aspects of parasitic lesions caused by Stephanofilariasis on the udder of nursing cows and to evaluate the viability of a therapeutic protocol. Forty lactating cows with characteristic Stephanofilariasis lesions were divided into two groups, GI and GII. The wounds on the udder of the GI cows were cleansed with sodium hydrochloride and treated topically with an ointment consisting of trichlorphone, ivermectine, dexamethasone, calendula, zinc oxide and an adherent ointment of sodium vaseline, associated with the parenteral application of 1% ivermectine. GII served as control group and was left untreated. Twelve cows (60%) of GI had recovered on the 45th day of treatment and 8 cows (40%) showed clinical cure within 45-60 days. The diagnosis of Stephanofilaria stilesi infection is generally presumptive. Epidemiologically-related aspects, clinical findings and positive response to treatment help to confirm the disease. Histopathological exams also assist in the diagnosis when the presence of nematodes can be revealed, although this finding is not frequent. The therapeutic protocol employed proved to be economically viable and efficient, with recovery of all the lesions.O presente trabalho objetivou descrever aspectos epidemiológicos, clínicos e histológicos das lesões e avaliar a viabilidade de um protocolo terapêutico para estefanofilariose localizada na pele do úbere de vacas lactantes. Utilizou-se no estudo 40 fêmeas bovinas de aptidão para leite em lactação com lesões características de estefanofilariose. Os animais foram distribuídos em dois grupos (GI e GII), sendo as feridas dos bovinos que constituíram o GI higienizadas com hipoclorito de sódio e tratadas diariamente com aplicação tópica de pomada contendo triclorfon, ivermectina, dexametasona, calêndula, óxido de zinco e pomada aderente de vaselina sódica, associada à aplicação parenteral de ivermectina a 1%. O GII foi utilizado como controle não sendo tratado. Do total de bovinos que fizeram parte do GI, 12 (60%) recuperaram-se até o 45o dia de tratamento e oito (40%) tiveram a cura clínica entre 45-60 dias. O diagnóstico de estefanofilariose geralmente é presuntivo, sendo que os aspectos relacionados à epidemiologia, achados clínicos e à resposta positiva ao tratamento auxiliam na confirmação da enfermidade. Os exames histopatológicos auxiliam no diagnóstico revelando a presença do nematódeo, embora a observação do parasito não seja freqüente. O protocolo terapêutico empregado mostrou-se economicamente viável e eficiente, com recuperação de todas as lesões.

This study was developed to evaluate the repellent activity of N,N-diethyl-3-methylbenzamide (DEET) against Amblyomma cajennense nymphs. Two repellent bioassays were compared and the effective concentration and repellent time were calculated. The fingertip test was accomplished to evaluate in vivo four concentrations of the compound (0.200; 0.100; 0.050 and 0.025 mg.cm-2) and the filter-paper bioassay to evaluate in vitro the two highest concentrations. The compound provided repellence higher than 90% in all concentrations and at least 95% repellency in the highest concentration over 5 hours. The effective concentration against 50% of tested nymphs (EC50) was 0.006 mg.cm-2 and the EC99 was 0.036 mg.cm-2. Those concentrations were lower than the ones obtained against other tick species, denoting the effectiveness of DEET against A. cajennense. The repellency time against 50% of the ticks (RT50) was 4.8 hours and the RT90 was 2.7 hours. Both bioassays were adequate to evaluate A. cajennense repellency and provided similar results; however the in vivo test is more appropriate to estimate the effective concentration and repellency time.Este estudo foi conduzido com o objetivo de avaliar a atividade repelente do N,N-diethyl-3-methylbenzamide (DEET) sobre ninfas de Amblyomma cajennense. Dois bioensaios para a avaliação de repelência foram comparados e cálculos da concentração eficaz e do tempo de repelência foram realizados. Foram empregados o bioensaio da ponta do dedo, para avaliação in vivo de quatro concentações do químico (0,200; 0,100; 0,050 e 0,025 mg.cm-2) e o bioensaio do papel filtro, para a avaliação in vitro das duas concentrações mais altas. O composto conferiu mais de 90% de repelência em todas as concentrações utilizadas e 95% de repelência por mais de cinco horas na maior concentração. A concentração do composto efetiva contra 50% das ninfas testadas (CE50) foi de 0,006 mg.cm-2 e a CE99 foi de 0,036 mg.cm-2. Estas concentrações são mais baixas do que as observadas em outras espécies de carrapatos, denotando a efetividade do princípio contra A. cajennense. O tempo de repelência de 50% dos carrapatos (TR50) foi de 4,8 horas e o TR90 de 2,7 horas. Os dois bioensaios avaliados permitiram a observação de percentuais de repelência igualmente altos e se mostraram adequados para tal avaliação, sendo que o teste in vivo é mais indicado para cálculo da concentração eficaz e da duração da repelência.

To ascertain whether brown dog tick Rhipicephalus sp. infests resistant (beagle) and susceptible (English cocker spaniel) dogs differently, five animals of each breed were maintained in a kennel whose walls were infested with 7,000 larvae, 320 nymphs, 80 males and 80 females, in 3 infestations, at 10-day intervals. Five times more ticks were found on cocker spaniels (498) than on beagles (96). Substances were collected by rubbing pieces of clean flannel on the dogs for 15 min and these were tested for arrestment and attractiveness of ticks. Three choices were offered: cocker extract vs. control; beagle extract vs. control, and cocker extract vs. beagle extract. When allowed to choose between substances rubbed from dogs and a control, more ticks were arrested by extracts from the cockers than from beagles. In the arrestment tests with only a choice between substances from dogs of each breed, more ticks were arrested by cocker substances. To test for attraction, capsules containing adsorbent were used and the tests were carried out in a Y-olfactometer. Fifteen males and 15 females were tested, for each treatment. In the olfactometer, the ticks were not attracted to the odor of either breed, however the odor of the Beagle was apparently repellent. These results indicate that R. sanguineus can use substances from the dogs to differentiate susceptible English Cocker Spaniels from resistant Beagles.

The objective of this study was to evaluate differences in susceptibility to Rhipicephalus sanguineus (Latreille) of two breeds of dogs: English cocker spaniel and beagle. Three artificial infestations of ticks using a capsule on the back of the dogs were carried out at 15 day intervals. Six dogs of each breed were infested with 100 larvae, 50 nymphs and 20 adults (10 males and 10 females). Every 2 days, the ticks on the dogs were evaluated and the engorged ones counted and collected. The ticks were stored in climatic chambers and inspected every two days for 14 days. The following parameters were recorded: number of engorged ticks, engorgement period, percentage of ecdysis, female weight, conversion of body weight to eggs and larval hatchability. In the ticks recovered from the cocker spaniel, higher percentages of ecdysis of larvae and nymphs, greater number of adults attached and engorged and higher reproductive performance of the females (conversion to eggs and hatchability) were observed. The period ...

This study aimed to identify 2,6-dichlorophenol (2,6-DCP) in Amblyomma cajennense and to evaluate its role in A. cajennense and Rhipicephalus sanguineus courtship. Hexanic extract from attractive females was purified by solid phase extraction and the phenol was identified by the single ion monitoring method using GC/MS. In an olfactometer, the responses of A. cajennense and R. sanguineus males to females, control rubber septa or rubber septa impregnated with 2,6-DCP at 50, 500, and 5000 ng, respectively, were studied. 2,6-DCP was identified in A. cajennense extract and the males oriented themselves toward the concentration of 500 ng. These septa and the females were recognized as copula partners. The septa treated with 2,6-DCP did not attract and were not even recognized by the R. sanguineus males, whereas the females were recognized. Due to the presence of 2,6-DCP in A. cajennense and the results of biological bioassays, it was concluded that this compound acts as an attractant and mounting sex pheromone in this tick, but it does not play any role in R. sanguineus courtship.

This experiment aimed to evaluate the efficacy of sunflower meal and sunflower seeds to control Boophilus microplus in naturally infested steers. The experiment was developed in the Dairy Cattle Facilities of the Veterinary College - UFG. Two herds of steers (Holstein x zebu) were allotted in a randomized block design in 2x10 factorial arrangement with six repetitions on Brachiaria decumbens pastures. After 14 days, weekly for two months, B. microplus females > 4 mm were counted, blood samples were collected and the animals were weighed. The B. microplus engorged females were collected to evaluate reproductive parameters. Blood samples were processed to determine: hematocrit, total protein, fibrinogen and leukocytes. The results had been submitted to the analysis of variance and the averages compared for the Scott-Knott test (5%). Tick counts, index (%), larval eclosion, hematocrit, total protein, fibrinogen and leukocytes were similar between treatments. The results do not corroborate the empirical reports concerning the effectiveness of the sunflower to control B. microplus in crossbred steers. KEY-WORDS: Blood values, oily seeds, parasites, tick count. Objetivou-se avaliar a ação do farelo ou das sementes de girassol no controle de Boophilus microplus em novilhos mestiços (holandês x zebu) infestados naturalmente. O experimento foi desenvolvido no Setor de Bovinocultura do Departamento de Produção Animal da Escola de Veterinária (EV) da UFG. Foram utilizados dois lotes de animais, distribuídos inteiramente ao acaso num fatorial 2 x 10 com seis repetições, em piquetes de Brachiaria decumbens, onde foram suplementados. Após quatorze dias de experimento e a cada sete dias, durante dois meses, num curral de manejo, efetuaram-se a contagem das fêmeas de B. microplus > 4 mm, as coletas de sangue e as pesagens dos bovinos. Colheram-se fêmeas ingurgitadas de B. microplus para avaliação de parâmetros reprodutivos. Amostras de sangue foram processadas para determinação dos parâmetros sangüíneos: hematócrito, proteína plasmática total, fibrinogênio e leucócitos. Submeteram-se os resultados à analise de variância e compararam-se as médias pelo teste de Scott-Knott a 5%. Não houve diferenças entre os tratamentos quanto às contagens de carrapatos, percentagem de índice de conversão em ovos, eclodibilidade, hematócrito, proteína total, fibrinogênio e leucócitos. Os resultados não corroboraram as observações empíricas acerca da eficácia do girassol sobre o Boophilus microplus, em bovinos leiteiros mestiços. PALAVRAS-CHAVES: Contagem de carrapatos, desempenho, parasitos, valores sangüíneos.

This study was carried out with the objective of evaluating the efficacy of a 2,6-dichlorophenol (2,6-DCP) lure to control Dermacentor nitens (Acari: Ixodidae). Slow-release formulations of the pheromone formulated with and without cypermethrin were prepared. Olfactometer bioassays were used to define the best dose of the pheromone and to evaluate the effect of cypermethrin with 2,6-DCP attractiveness. Sexually active males were released 15 cm from 2 cmx1 cm pieces of polypropylene treated with different odors: 2,6-DCP in a liposphere system (1.5, 30 and 300 microg--without cypermethrin and 30 microg--with cypermethrin) and 2,6-DCP in hexane (30 microg). The tests were conducted 7 and 15 days after the preparation of the odor sources. The percentages of males that oriented, or showed directional movement toward the stimulus, and their tracks were recorded. Lures (10 cmx2 cm pieces of polypropylene) treated with the best dose of the liposphere formulation (30 microg) were prepared. The lures were evaluated in horses that had been artificially infested with D. nitens. The horses' ears were infested with 3000 D. nitens larvae per ear, once weekly for 4 weeks. The animals were divided into three groups: control, 2,6-DCP and 2,6-DCP+cypermethrin. On day 0, the lures of their respective treatments were attached to the horses' napes. From days 6 to 20 after attachment, female ticks of 4 mm or over in length were counted on the ears, every 2 or 3 days. Olfactometer analysis showed higher orientation to 30 microg dose and more prolonged release of the pheromone in the liposphere formulation than in hexane; cypermethrin did not interfere with the attractive effect of the pheromone. The lures were efficient in the first 10 days after attachment, when the mean number of females was higher in the control group (24.9) than in 2,6-DCP and cypermethrin (5.4), and 2,6-DCP (9.2) groups. After that period the number of females was similar in the control and treated groups. These results indicate that 2,6-DCP lures used in a liposphere formulation can control D. nitens for at least 10 days by preventing its copulation. However, further evaluation of longer-term pheromone release under natural conditions is needed in order to validate this kind of control. In addition, the use of extra lures on the horse's tail may help to control populations on the hindquarters.

The seasonal dynamics of Rhipicephalus sanguineus ticks was developed in dogs from a Police Unit in Goiânia, Goiás, Brazil, from July 2001 to July 2002. The study was carried out on seven naturally infested dogs (two English Cocker Spaniels and five mongrel dogs), with ages between six months and 10 years. Every two weeks, the numbers of feeding larvae, nymphs, and adults were determined. Dogs showing infestation levels above 500 adult ticks received three acaricide treatments. Considering that the treatments had affected the development of some peaking populations of ticks, it was inferred the occurrence of the following peaks: - larvae (four peaks): from August to November, from November to February, from March to May, and from May to July; - nymphs (five peaks): from July to September, from October to December, from December to February, from March to May, and from June to July; - adults (four peaks): from July to October, from October to January, from January to March, and from April to July. The occurrence of these consecutive peaks of activity of each stage of R. sanguineus may indicate that this tick can develop up to four generations per year in Goiânia. On the other hand, if the acaricide treatment did not interfere with the development of R. sanguineus peaks, more than four peaks of each stage have occurred on the dogs. In this case, it is acceptable to infer that more than one population of R. sanguineus was developing within the kennel concomitantly. The mean numbers of each tick stage was similar in the different seasons. The main attachment sites were located on the neck, chest, forelegs, armpits, ears, between toes and on the head. The number of adult ticks feeding on English Cocker Spaniel dogs was 1.4 to 11.5 times higher than that feeding on mongrel dogs.O estudo de dinâmica sazonal de Rhipicephalus sanguineus foi desenvolvido em cães de uma Unidade da Polícia de Goiânia, Goiás, Brasil, de julho de 2001 a julho de 2002. Sete cães naturalmente infestados com R. sanguineus (dois da raça Cocker Spaniel Inglês, e cinco cães sem raça definida), com idades variando de 6 meses a 10 anos, foram utilizados no monitoramento da infestação. A cada duas semanas, o número de larvas, ninfas e adultos parasitando os animais era contado. Três tratamentos acaricidas foram feitos nos cães que tiveram níveis de infestação de 500 adultos. Considerando que os tratamentos interferiram no desenvolvimento de alguns picos do carrapato, pôde-se inferir que ocorreram nos quatro picos de larvas: de agosto a novembro, de novembro a fevereiro, de março a maio e de maio a julho; cinco picos de ninfas: de julho a setembro, de outubro a dezembro, de dezembro a fevereiro, de março a maio e de junho a julho, e quatro picos de adultos: de julho a outubro, de outubro a janeiro, de janeiro a março e de abril a julho. A ocorrência destes picos consecutivos de cada estágio pode indicar que o R. sanguineus realiza quatro gerações anuais em Goiânia. Por outro lado, se os tratamentos não interferiram no desenvolvimento dos picos de atividade, mais de quatro picos de cada estágio ocorreram nos cães. Então, é aceitável supor que mais de uma população de R. sanguineus estava se desenvolvendo no canil, ao mesmo tempo. O número médio de carrapatos de cada estádio foi similar nas estações do ano. Os sítios preferenciais de fixação foram o pescoço, o peito, as patas, as axilas, as orelhas, os espaços interdigitais e a cabeça. O número de carrapatos contados nos cães da raça Cocker Spainel Inglês foi de 1,4 a 11,5 vezes maior que o número observado nos cães sem raça definida.

Studies have shown that the brown dog tick, Rhipicephalus sanguineus sensu lato, when fed on the beagle breed of dog, Canis lupus familiaris, development negatively affected in comparison with tick development after feeding on the English cocker spaniel breed. Thus leading to the suggestion that beagle dogs are be tick-resistant dogs. Behavioural studies have demonstrated that more ticks are attracted by extracts from cocker spaniels than from beagles and that the odour of beagles is a repellent. To test the hypothesis that resistant hosts produce repellent compounds, we undertook comparative chemical analysis on beagle odour and cocker spaniel extracts using coupled high-resolution gas chromatography-mass spectrometry (GC-MS) and also used Petri-dish and olfactometer behavioural assays to assess the response of ticks to identified non-host compounds. The beagle odour extracts contained almost three times as many chemical compounds as cocker spaniel samples. Several non-host compounds were identified, i.e. 2-hexanone, benzaldehyde, nonane, decane and undecane. In Petri-dish assays, 2-hexanone was repellent at 30 min at concentrations of 0.200 and 0.050 mg cm(-2), whilst at 10 min, the 0.100 mg cm(-2) concentration was repellent. Benzaldehyde repelled ticks at 30 min (0.200 mg cm(-2)) and at 5 min (0.050 mg cm(-2)). Undecane was repellent for R. sanguineus s.l. ticks for the first 5 min at the highest concentration tested. Nonane and decane did not show any significant repellency at any concentration or time evaluated. When 2-hexanone and benzaldehyde were combined, an increase in the repellency rate was observed, with activity comparable or better than N,N-diethyl-3-methylbenzamide (DEET). In olfactometer bioassays, a 1:1 mixture of 2-hexanone:benzaldehyde and DEET were repellent for R. sanguineus s.l. adults at the concentration of 0.200 mg cm(-2). This study identified non-host semiochemicals that mediate avoidance of the beagle dog breed by R. sanguineus s.l. This finding may enable development of new approaches to control this tick.

Rhipicephalus sanguineus é um parasito natural de cães que eventualmente pode parasitar outros hospedeiros, entre eles o homem. Para humanos, este carrapato é vetor do agente da febre botonosa (Rickettsia conori) na Europa e vetor potencial no Brasil dos agentes da febre maculosa (Rickettsia rickettsii) e da borreliose Lyme símile (Borrelia sp.). Considerando a importância deste carrapato, desenvolveu-se este trabalho com o objetivo de avaliar a sua ocorrência em humanos no Brasil, uma vez que não se conhecem outros relatos. A presença de carrapatos foi avaliada em 46 trabalhadores de ambos os sexos (25 mulheres e21 homens), de oito clínicas e três canis, por meio de questionário e da identificação dos carrapatos encontrados. Do total de pessoas avaliadas, 68% das mulheres e 71% dos homens relataram já ter encontrado carrapatos andando ou fixados, após contato com cães. Foram colhidos três larvas, uma ninfa e quatro adultos (três machos e uma fêmea) sendo todos identificados como da espécie R. sanguineus. Desta forma este é o primeiro relato do parasitismo de humanos por este carrapato no Brasil. PALAVRAS-CHAVE: Carrapatos de cão, humanos, Brasil.

Este trabalho objetivou avaliar a influência do peso inicial da fêmea e da estação do ano na conversão em ovos de Boophilus microplus. O índice de eficiência reprodutiva (IER) de 411 fêmeas pesando entre 31 e 360 mg foi correlacionado com seu peso inicial. Para avaliar a influência das diferentes estações do ano neste parâmetro biológico, dez fêmeas ingurgitadas de B. microplus pesando acima de 150 mg foram colhidas, a cada duas semanas, e mantidas em condições climáticas controladas até a determinação do IER. Uma relação curvilinear foi observada entre o peso das fêmeas e o IER. Fêmeas pesando entre 151 e 360 mg tiveram IER’s mais altos (variando de 44,9% a 51,4%) do que aquelas mais leves, as quais apresentaram uma menor capacidade de conversão em ovos (variando de 31,4% a 39,0%). Foi observado que a capacidade de as fêmeas converterem o peso em ovos variou sazonalmente. Os mais altos IER foram observados no período seco, de abril a setembro (47,6% a 58,3%), do que no período chuvoso, de outubro a março (40,2% a 43,6%) (P

This study reports the occurrence of Nasonia vitripennis (Walker) (Hymenoptera: Pteromalidae) as parasitoid of Cyrtoneurina pararescita (Diptera: Muscidae) (Couri, 1995) in bovine feces obtained in Goiânia, Goiás state, Brazil. Bovine manure samples, collected at two weeks intervals, were taken to the laboratory and the pupae were extracted by water flotation. Each pupa was placed in capsules of gelatin until the emergence of dipterous or their parasitoids. The parasitism percentage was of 2.4%. This paper reports the first occurrence of N. vitripennis as parasitoid of C. pararescita worldwide.

The population dynamics of all stages of the Cayenne tick, Amblyomma cajennense (Fabricius) (Acari: Ixodidae) on horses was evaluated over a period of 2 years in the district of Pedro Leopoldo, State of Minas Gerais, Brazil. Every 14 days, the left side of 20 horses was brushed for collection of immature stages; counts of adults were also undertaken. Infestation by larvae was detected from April to August, whereas nymphs were observed from June to October. Infestation by adults was detected throughout the year, and the highest population density occurred from September to March. The number of males was always higher than the number of females, but with considerable reduction in the male : female ratio between April and July. It was observed that 25% of the horses carried 41% of the infesting ticks, and 20% carried only 10% of the ticks during the entire period of the study.

The efficacy of ripe fruit extracts of Melia azedarach L. (Rutales: Meliaceae) was evaluated against the tick, Boophilus microplus (Canestrini) (Acari: Ixodidae). Ripe fruits of M. azedarach dried and powdered were extracted by Soxhlet apparatus successively using hexane, CHCl3 and 96% aqueous ethanol. Larvae and engorged females were immersed in decreasing concentrations from 0.25% to 0.015% of each extract. The mortality of larvae was evaluated 24, 72 and 168 h after treatment. The effectiveness of treatment against engorged females was assessed by measuring egg production. All tested extracts caused mortality of B. microplus larvae, with higher mortality rates observed in CHCl3 (100%) and hexanic extract (98%) than in ethanolic extract (50%) 168 h after treatment. The mortality was dependent on concentration and on time after treatment. Similarly hexanic and CHCl3 extracts showed higher effectiveness (varying from 14% to 100%) against B. microplus engorged females than ethanolic extract (varying from 0% to 46%). Melia azedarach extracts did not kill the adult females, but inhibited partially or totally egg production and embryogenesis. These results show that the less polar the extract of M. azedarach ripe fruits the more its effectiveness against larvae and engorged females of B. microplus. This plant may therefore be useful in the control of resistant B. microplus populations.

The objective of this study was to investigate some aspects of horse resistance to natural infestations of Anocentor nitens and Amblyomma cajennense over a 2-year period. Free-living stages of A. nitens were used to evaluate the influence of season of the year on horse resistance. Every 2 weeks, 10 selected engorged females, weighing 150–329 mg, were removed from naturally infested horses and were individually placed into glass tubes closed with a cotton stopper, and maintained in an incubator. The biological parameters evaluated varied according to the season of the year, i.e., reproductive efficiency, maximum larval survival (MLS) and egg-hatching rates were significantly lower in spring/summer than in fall/winter. At 14-day intervals, females of A. nitens and A. cajennense were counted on each side of the body of five mares. A comparison between the animal with the lowest infestation and the animal with the highest infestation showed greater differences in animals infested with A. nitens than those infested with A. cajennense. Ten animals were found to carry 64.9% of the total parasite burden of A. cajennense and 88.6% of the highest infestations of A. nitens females. A seasonal variation on intensity of horse resistance to A. nitens was observed during the study. However, this was not observed for A. cajennense. Cross-resistance was observed in animals with the highest total number of A. cajennense and the highest number of A. cajennense adults (r=0.817), larvae (r=0.756), and A. nitens females (r=0.799). These results led to the conclusion that changes in horse resistance to A. nitens occur seasonally. As far as the total population of A. cajennense and the female stage of A. nitens are concerned, horses develop cross-resistance.

The objective of this study was to evaluate the role of2,6-dichlorophenol (2,6-DCP) as sex pheromone of Anocentornitens. Sex pheromones were extracted by submerging 150 females fed for 6 days in hexane (3 ml) for two hours and sonicating them for15 min. The extract was analyzed by GC-MS employing the Single Ion Monitoring (SIM) method. Identification of 2,6-DCP was based on the comparison of mass spectra with a computer search using the NIST library and by matching the mass spectrum of the peak at the retention time of 2,6-DCP from extract sand the synthetic product. In an olfactometer, males were released at 2.5cm from females, control rubber septa and impregnated rubber septa with increasing concentrations of 2,6-DCP (50, 500 and 5000 ng). A higher percentage of orientation and higher frequencies of angles between 0° and 10° were observed for males tested with females than with controls. Attraction of males to dummies impregnated with 2,6-DCP was observed with highest response (100%) at 50 ng. There was a gradual decrease of responsiveness of males with increasing concentration of 2,6-DCP (70 to 75%).This compound stimulated a behavior of mounting and ventral positioning ofA. nitens males at the lowest 2,6-DCP concentration where as dummies impregnated with 2,6-DCP higher than 50 ng concentration inhibited these behaviors. Therefore, we can conclude that 2,6-DCP can elicit the complete behavior sequence of orientation, location, mounting and ventral positioning behaviors and plays a role as an attractant and, as a mounting sex pheromone in A. nitens.

A study on the population behavior of Amblyomma cajennense larvae, nymphs and adult free-living stages was carried out in Pedro Leopoldo County, Minas Gerais State, Brazil, from July 1995 to July 1997. Larvae were collected from pasture from April to October using the technique of drag sampling with flannelette. The maximal larval population was observed during autumn (May) representing, respectively, 48 and 82% of the total numbers recovered during the first and the second years of the experiment. Nymphs and adults were captured throughout the year by the use of traps with carbon dioxide as chemical attractant. The highest population of nymphs occurred during the winter (July), representing 39.5% of the total collected specimens. Adults had the highest population density on pasture during spring and summer, i.e., from August to May, with peaks in January and February, representing 46 and 38.3% of the total collected specimens during the first and the second year of study, respectively.

The aim of this study was to investigate whether there are sex pheromones in the tropical horse tick, Anocentor nitens (Neumann). When virgin males and females, fed on rabbits for 3-7 d, were tested reciprocally, there was a direct correlation between attractiveness and the period of feeding; attraction was greater (and with the fastest responses) in males and females fed for at least 6 d (sexually active males and confirmed attractive females). The capacity of sexually active males to orient topward confirmed attractive females decreased as the emission distance increased; the maximum distance that evoked a response by males was 6 cm. Confirmed attractive females lost their attractiveness approximately 2 h after being separated from the host, or after being killed by ethanol injection, although some females continued to attract sexually active males up to 4 h after death. An extract was produced by immersing confirmed attractive females in hexane and submitting them to ultrasound. Sexually active males were more attracted to and spent more time on glass bead dummies treated with this extract when compared with those treated with the hexane alone. Our results indicate the presence of at least 2 sex pheromones (attractant and mounting) in attractive females of A. nitens.