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

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Although tick infestation is a significant health problem in livestock, there are limited studies on the dermatopathological aspects of natural tick infestation in cattle. This study aimed to describe the gross and histologic aspects of cutaneous lesions caused by tick infestation in cattle. Thirteen cases were selected based on necropsy data from a 10-year retrospective study. Predispositions were observed in beef cattle (P = .049) and the Angus breed (P = .012), and lesions occurred mainly in the fall (P = .007). Gross lesions included hypotrichosis (13/13; 100%), scales (12/13; 92%), alopecia (11/13; 85%), ulcers (7/13; 54%), crusts (7/13; 54%), and erosions (2/13; 15%). These gross lesions were mainly located in the thorax (12/13; 92%), head (11/13; 85%), abdomen (10/13; 77%), neck (9/13; 69%), limbs (9/13; 69%), and perineum (9/13; 69%). Histologically, all cases had ticks adhered to the epidermis with erosions (13/13; 100%), ulcers (11/13; 85%), orthokeratotic hyperkeratosis (13/13; 100%), irregular acanthosis (13/13; 100%), intraepidermal pustules (13/13; 100%), crusts (10/13; 77%), and ballooning degeneration (4/13; 31%). In the dermis, just below the tick insertion site, there was coagulation necrosis, fibrin deposition, and inflammatory infiltrate composed of mixed cells (neutrophils, lymphocytes, plasma cells, macrophages, and few eosinophils) (9/13; 69%), neutrophils (3/13; 23%), or eosinophils (1/13; 8%). This study reinforces the different patterns of cutaneous lesions caused by tick infestation in cattle, which should be considered as a potential cause of dermatitis in this species.

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This study aimed to evaluate the sequence variations of the GABA-Cl gene of Rhipicephalus (Boophilus) microplus ticks from Argentina with different resistance levels to fipronil. Genomic DNA was obtained from engorged females (n = 50) of fipronil-susceptible and resistant tick field populations from five localities in northern Argentina. Tick populations were tested for fipronil resistance by in vitro larval packet test. DNA encoding amino acid residues 264-360 of the GABA-Cl was amplified by PCR. PCR products were sequenced and the translated amino acid sequences were aligned and compared among each other and with sequences of the GABA-Cl belonging to the Brazilian and Uruguayan reference strains fipronil-susceptible (Mozo) and resistant (RFSan and Juarez). All the GABA-Cl amino acid sequences obtained from the R. microplus specimens from Argentina were identical, regardless of the fipronil resistance-susceptibility status of each population. Mutations present in GABA-Cl sequence of RFSan and Juarez strains were not present in any of the populations from Argentina analyzed. These results indicate the failure of this gene as a molecular marker of resistance to fipronil, at least in the R. microplus populations from northern Argentina.

RESUMEN

Although Brazilian livestock is considered one of the most productive in the world, the losses caused by parasites still greatly limit these activities and its incorrect control through traditional synthetic chemicals has caused problems such as parasitic resistance. The present study evaluated the anthelmintic and acaricidal action of ethanolic extract (EE) and essential oil (OE) obtained from Achyrocline satureioides inflorescences against an endo and an ectoparasite of great importance in sheep and cattle. The action against Haemonchus contortus was evaluated by the Larval Development Test (LDT) and the Egg Hatching Test (EHT), while the acaricidal potential against Rhipicephalus (Boophilus) microplus was evaluated by the Adult Immersion Test (AIT) and Larval Package Test (LPT). Chemical analyzes were performed by liquid chromatography coupled to mass of spectrometry (LC-MS) and gas chromatography coupled to mass spectrometry (GC-MS) in order to evaluate the chemical composition of EE and EO, respectively. Luteolin (m/z 285), quercetin (m/z 301) and methyl quercetin (m/z 315) were the major compounds detected in the A. satureioides EE, while 41 compounds were identified in EO. Among them, the major compounds were caryophyllene oxide (15.4%), limonene (10.9%), trans-calamenene + Î´-cadinene (8.0%), (E)-caryophyllene (5.5%), spathulenol (5.1%) and α-pinene (4.5%). Against H. contortus, by EHT, the EE and EO showed LC50 of 83.14 mg mL-1 and 10.42 mg mL-1, respectively. In LDT, LC50 were 0.16 mg mL-1 and 0.42 mg mL-1, respectively by EE and EO. In the AIT assay for R. (B.) microplus tick LC50 obtained for EE and EO were 76.43 mg mL-1 and 114.35 mg mL-1, respectively. EE at 100 mg mL-1 completely inhibited egg laying, while the EO at 50 mg mL-1 completely inhibited larval hatching. No significant larvicidal effect was observed in LPT for both extracts. The EE and EO presented a high efficacy at low concentrations in the inhibition of egg hatching and larval development of H. contortus. Although both extracts did not show consistent larvicidal action, the results were significant in inhibiting the oviposition of R. (B.) microplus engorged females.

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Os carrapatos são os ectoparasitos que causam maiores prejuízos para a produção de bovinos, e em particular o Rhipicephalus (Boophilus) microplus é responsável por graves prejuízos para os produtores de carne e leite, e seu controle vem sendo dificultado pela resistência desses ácaros de pequeno porte aos carrapaticidas comerciais. O objetivo do presente trabalho foi avaliar a eficiência in vitro de 08 (oito) bases químicas presentes nos principais acaricidas do mercado, sobre o Rhipicephalus (Boophilus) microplus. Para tanto, amostras de carrapatos foram coletadas de uma propriedade rural do município de Vazante, MG, para a realização do teste de imersão de teleóginas (biocarrapaticidograma). As associações das bases químicas Cipermetrina 20% + Clorpirifós 50%; Cirpemetrina 15% + Clorpirifós 30% + Fention 15%; Cipermetrina 15% + Clorpirifós 25% + Butóxido de Piperonila 15%+ Citronela 1% e Clorpirifós 50% + Cipermetrina 6%, apresentaram eficiência de 100% no teste in vitro. Entretanto, Diclorvós 50% + Clorpirifós 20%; Supona 50%; Amitraz 12,5% e a Deltametrina 25% apresentaram eficiência menor que 95%. Os resultados obtidos sugerem uma relação direta entre produtos presentes no mercado versus resistência do Rhipicephalus (Boophilus) microplus, enfatizando a necessidade do monitoramento dos mecanismos de resistência associado à implementação de um programa de controle estratégico de carrapatos, levando ao manejo adequado de acaricidas e uma política de fiscalização atuante por parte dos órgãos competentes com relação aos produtos químicos disponíveis no mercado para o controle do Rhipicephalus (Boophilus) microplus.(AU)

Ticks are the ectoparasites that cause greater damage to the production of cattle, and in particular Rhipicephalus (Boophilus) microplus is responsible for serious damage to meat and milk producers, and its control has been hampered by the resistance of these mites. small scale to commercial ticks. The objective of the present work was to evaluate the in vitro efficiency of 08 (eight) chemical bases present in the main acaricides in the market, on Rhipicephalus (Boophilus) microplus. For that, samples of ticks were collected from a rural property in the municipality of Vazante, MG., Brazil, to perform the teleogener immersion test (biocarrapaticidogram). The associations of the chemical bases Cypermethrin 20% + Chlorpyrifos 50%; Cirpemetrina 15% + Chlorpyrifos 30% + Fention 15%; Cypermethrin 15% + Chlorpyrifos 25% + Piperonyl Butoxide 15% + Citronella 1% and Chlorpyrifos 50% + Cypermethrin 6%, showed 100% efficiency in the in vitro test. However, Dichlorvós 50% + Chlorpyrifos 20%; Suppose 50%; Amitraz 12.5% and Deltamethrin 25% showed efficiency less than 95%. The results obtained suggest a direct relationship between products present in the market versus resistance of Rhipicephalus (Boophilus) microplus, emphasizing the need to monitor resistance mechanisms associated with the implementation of a strategic tick control program, leading to the appropriate management of mites and a active inspection policy by the competent bodies regarding the chemicals available on the market for the control of Rhipicephalus (Boophilus) microplus.(AU)

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ABSTRACT The aim of the present study was to evaluate the resistance of tick populations on 16 family farms that were members of the agricultural producers cooperative of the São Pedro region of the state of São Paulo (COOPAMSP). Bioassays were conducted on nine commercial products in 2018 and 2019. Their active agents were as follows: deltamethrin, amitraz, cypermethrin + chlorpyrifos + citronella, cypermethrin + chlorpyrifos + fenthion, cypermethrin + chlorpyrifos + piperonyl butoxide, dichlorvos + chlorpyrifos, cypermethrin, chlorfenvinphos + dichlorvos, and ivermectin. On some farms, a larval packet test (LPT) was also performed. Overall, four acaricides presented mean efficacy greater than 89%, among which two were associations of pyrethroids + organophosphates and two were associations of organophosphates + organophosphates. Deltamethrin, cypermethrin and ivermectin presented mean efficacy lower than 50%. In the bioassays using the LPT, all five farms showed resistance to diazinon, while only one farm presented resistance to cypermethrin. The results were handed over to each farmer with appropriate guidance for treatments. This study demonstrated that the important points to be implemented related directly to use control strategies, based on direct assistance for farmers and diagnosis of tick population sensitivities.

RESUMEN

Ectoparasitic infestation in dairy cattle, the most common being Rhipicephalus (Boophilus) microplus, causes significant loss in production. The control of ectoparasites often occurs incorrectly, resulting in resistance to the active ingredients and residues in milk. To understand of acaricide use in the microregion of Alfenas, Minas Gerais (Brazil), questionnaires were applied to the owners of 100 dairy farms in the region and were selected randomly. Dairy farms were allocated according to production scale: up to 150 liters/day, 151-400 liters/day and more than 400 liters/day. The interviewees were asked about production characteristics, acaricide management and active ingredients. The interview answers were subjected to descriptive analysis. Results showed that all properties, independent of production-scale, used acaricides. The most cited was: Cypermethrin Chlorpyrifos Citronellal (31%), Fluazuron (18.6%) and Fipronil (17%). Among the interviewed, 41,1% use drugs that have restrictions that are not allowed in legislation for use in lactating dairy cows (fluazuron, fipronil, ivermectin). 15% affirmed they werent aware of the withdrawal period of medication and 73% change in the active ingredient used. In order to revert this antiparasitic drugs resistance situation and contamination of milk with drug residues, it is necessary to focus on the awareness of milk producers and training of labor.(AU)

A infestação por ectoparasitas em bovinos leiteiros, sendo o mais comum o Rhipicephalus (Boophilus) microplus, causa prejuízos significativos na produção. No entanto, o controle dos ectoparasitas geralmente ocorre incorretamente, resultando em resistência aos princípios ativos e presença de resíduos no leite. Para entender os padrões de uso de acaricidas na microrregião de Alfenas, Minas Gerais, Brasil, foram aplicados questionários aos proprietários de 100 fazendas leiteiras que foram classificadas de acordo com uma escala de produção: até 150 litros/dia, de 151 a 400 litros/dia e mais de 400 litros/dia. Os entrevistados foram questionados sobre características da produção, manejo do acaricida de gado e conhecimento sobre os princípios ativos. Todas as propriedades, independentemente da escala de produção, usavam acaricidas. Foram citados com maior frequência: Cipermetrina + Clorpirifós + Citronelal (31%), Fluazuron (18.6%) e Fipronil (17%). Entre os produtores entrevistados, 41,1 % fazem uso de drogas com restrição que não são atualmente permitidas na legislação para uso em vacas em lactação (fluazuron, fipronil, ivermectina). 15% dos produtores de leite afirmaram não estar cientes do período de carência dos medicamentos; outros relatam trocas constantes do princípio ativo utilizado. Para reverter a situação do uso indiscriminado de antiparasitários, é necessário focar na conscientização dos produtores de leite e na formação do trabalho.(AU)

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RESUMEN

The aim of the present study was to evaluate the resistance of tick populations on 16 family farms that were members of the agricultural producers' cooperative of the São Pedro region of the state of São Paulo (COOPAMSP). Bioassays were conducted on nine commercial products in 2018 and 2019. Their active agents were as follows: deltamethrin, amitraz, cypermethrin + chlorpyrifos + citronella, cypermethrin + chlorpyrifos + fenthion, cypermethrin + chlorpyrifos + piperonyl butoxide, dichlorvos + chlorpyrifos, cypermethrin, chlorfenvinphos + dichlorvos, and ivermectin. On some farms, a larval packet test (LPT) was also performed. Overall, four acaricides presented mean efficacy greater than 89%, among which two were associations of pyrethroids + organophosphates and two were associations of organophosphates + organophosphates. Deltamethrin, cypermethrin and ivermectin presented mean efficacy lower than 50%. In the bioassays using the LPT, all five farms showed resistance to diazinon, while only one farm presented resistance to cypermethrin. The results were handed over to each farmer with appropriate guidance for treatments. This study demonstrated that the important points to be implemented related directly to use control strategies, based on direct assistance for farmers and diagnosis of tick population sensitivities.

Asunto(s)

RESUMEN

Abstract Ectoparasitic infestation in dairy cattle, the most common being Rhipicephalus (Boophilus) microplus, causes significant loss in production. The control of ectoparasites often occurs incorrectly, resulting in resistance to the active ingredients and residues in milk. To understand of acaricide use in the microregion of Alfenas, Minas Gerais (Brazil), questionnaires were applied to the owners of 100 dairy farms in the region and were selected randomly. Dairy farms were allocated according to production scale: up to 150 liters/day, 151-400 liters/day and more than 400 liters/day. The interviewees were asked about production characteristics, acaricide management and active ingredients. The interview answers were subjected to descriptive analysis. Results showed that all properties, independent of production-scale, used acaricides. The most cited was: Cypermethrin Chlorpyrifos Citronellal (31%), Fluazuron (18.6%) and Fipronil (17%). Among the interviewed, 41,1% use drugs that have restrictions that are not allowed in legislation for use in lactating dairy cows (fluazuron, fipronil, ivermectin). 15% affirmed they weren't aware of the "withdrawal period" of medication and 73% change in the active ingredient used. In order to revert this antiparasitic drug's resistance situation and contamination of milk with drug residues, it is necessary to focus on the awareness of milk producers and training of labor.

Resumo A infestação por ectoparasitas em bovinos leiteiros, sendo o mais comum o Rhipicephalus (Boophilus) microplus, causa prejuízos significativos na produção. No entanto, o controle dos ectoparasitas geralmente ocorre incorretamente, resultando em resistência aos princípios ativos e presença de resíduos no leite. Para entender os padrões de uso de acaricidas na microrregião de Alfenas, Minas Gerais, Brasil, foram aplicados questionários aos proprietários de 100 fazendas leiteiras que foram classificadas de acordo com uma escala de produção: até 150 litros/dia, de 151 a 400 litros/dia e mais de 400 litros/dia. Os entrevistados foram questionados sobre características da produção, manejo do acaricida de gado e conhecimento sobre os princípios ativos. Todas as propriedades, independentemente da escala de produção, usavam acaricidas. Foram citados com maior frequência: Cipermetrina + Clorpirifós + Citronelal (31%), Fluazuron (18.6%) e Fipronil (17%). Entre os produtores entrevistados, 41,1 % fazem uso de drogas com restrição que não são atualmente permitidas na legislação para uso em vacas em lactação (fluazuron, fipronil, ivermectina). 15% dos produtores de leite afirmaram não estar cientes do "período de carência" dos medicamentos; outros relatam trocas constantes do princípio ativo utilizado. Para reverter a situação do uso indiscriminado de antiparasitários, é necessário focar na conscientização dos produtores de leite e na formação do trabalho.

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This study, was to evaluate the acaricidal effect of the essential oil (EO) and fractions (FR) obtained from Laurus nobilis leaves on Rhipicephalus (Boophilus) microplus. Eight fractions were obtained, however FR1: sabinene (37.83%), ß-pinene (13.50%), 1,8-cineole (12.66%), α-pinene (12.56%) and FR8: α-terpineol (79.19%) were highlighted as to the larvicidal potential when submitted by Larval Packet Test. The EO was tested by the Adult Immersion Test, at concentrations of 200.00; 100.00 and 50.00 µL/mL caused mortality of engorged females, egg mass reduction and hatching inhibition. Two fractions are shown to be efficient in controlling larvae FR8 (LC50 = 0.13 µL/mL, LC99 = 0.51 µL/mL) and FR1 (LC50 = 0.20 µL/mL, LC99 = 0.56 µL/mL). The fractionation of EO was determinant to elucidate which compounds were responsible for the larvicidal potential. This study opens new perspectives to direct new bioassays with the compounds obtained in the fractionation, since they present high potential on cattle tick larvae.

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Brazil has one of the largest commercial cattle herds in the world, which naturally coexist with an enormous number of parasitic species. Southern cattle tick, Rhipicephalus (Boophilus) microplus, is among these species, interfering with animal productivity and causing losses to the beef and dairy cattle sector. The use of chemical acaricides in the control of this mite has resulted in the emergence of resistant populations. In this sense, alternative control measures using plants as sources of botanical acaricides have shown to be effective. Eugenia pyriformis Cambess is a Brazilian plant with antioxidant and antimicrobial activity; however, there are no reports on its acaricidal activity in the literature. The present study aimed to evaluate the acaricidal and larvicidal potential of E. pyriformis leaf essential oil (EO) on southern cattle tick at different stages of the reproductive cycle. E. pyriformis leaves were collected and dried, and had their EO extracted by hydrodistillation (3h) using a modified Clevenger apparatus. Chemical analysis was performed by gas chromatography coupled with mass spectrometry (GC/MS), and 32 compounds belonging to the sesquiterpene class were identified: hydrocarbons (17.98%) and oxygenated forms (81.96%), with spathulenol (43.65%) and caryophyllene oxide (12.17%) as the most common. The EO was evaluated by the Adult Immersion Test at the concentrations (500.00 to 3.12mg/mL) in which the following parameters were measured: mortality of females (%), hatchability of eggs (%), and product efficiency (%). Larvae were assessed by the Larval Packet Test at concentrations ranging from 25.00 to 0.00004mg/mL. Lethal concentrations (LC) required for killing 50 and 99.9% of adult females and larvae were determined using Probit analysis. LC50 and LC99.9 of EO were 0.06 and 24.60mg/mL and 1,208.80 and 2,538mg/mL for larvae and adult females, respectively. Action of the EO in the free-living cycle of R. (B.) microplus larvae was another parameter assessed. To this end, the larvae were deposited in pots containing Brachiaria decumbens and, after migration to the leaf apex, a solution containing LC99.9 (24.60mg/mL) of the EO was sprayed. After 24h, 72.25% of the larvae had died, indicating stability of the EO when subjected to uncontrolled temperature and humidity conditions. The mechanism of action through which the EO killed the larvae and adult females was investigated by the Bioautographic Method, which showed inhibition of 3.15mg/mL of the EO on the acetylcholinesterase (AChE) enzyme. The results found in the present experiment indicate that E. pyriformis essential oil is an alternative in the control of southern cattle tick in the larval (parasitic) and free-living cycle (non-parasitic) stages under field conditions.(AU)

O Brasil dispõe de um dos maiores rebanhos bovinos comerciais do mundo, sendo natural que junto a esse rebanho, coexista uma enorme quantidade de espécies parasitárias; dentre estes o carrapato Rhipicephalus (Boophilus) microplus que interfere na produtividade animal, causando prejuízos à pecuária de corte e leite. A utilização de acaricidas químicos no controle deste ácaro tem causado o surgimento de populações resistentes e neste sentido, controles alternativos utilizando plantas como fontes de acaricidas botânicos têm se mostrado eficazes. Eugenia pyriformis Cambess é uma planta brasileira com atividades antioxidante e antimicrobiana, entretanto não há relatos da atividade acaricida. O objetivo do presente estudo consistiu na avaliação do potencial acaricida e larvicida do óleo essencial das folhas de E. pyriformis sobre o carrapato bovino nos diferentes estágios do ciclo reprodutivo. As folhas foram coletadas, secas e o OE extraído por hidrodestilação (3 horas) em aparelho Clevenger modificado. A análise química foi realizada por cromatografia gasosa acoplada à espectrometria de massas (CG/EM) sendo identificados 32 compostos, pertencentes à classe sesquiterpenos: hidrocarbonetos (17.98%) e oxigenados (81.96%); tendo como majoritários o spathulenol (43,65%) e caryophylene oxide (12,17%). O OE foi avaliado pelo teste de imersão de adultos nas concentrações (500,00 a 3,12mg/mL) onde foram mensurados os parâmetros: mortalidade das fêmeas (%), eclodibilidade dos ovos (%) e eficiência do produto (%). As larvas foram avaliadas pelo teste de imersão larval (Larval Packet Test) nas concentrações que variaram de 25,00 a 0,00004mg/mL. Foram determinadas as concentrações letais (CLs) necessárias para matar 50 e 99,9% das fêmeas adultas e das larvas utilizando a análise de Probitos. As CL50 e CL99,9 do OE foram (0,06 e 24,60mg/mL) para as larvas e (1.208,80 e 2.538mg/mL) para as fêmeas adultas, respectivamente. Outro parâmetro avaliado em nossa pesquisa foi mensurar a ação do OE no ciclo de vida livre das larvas de R.(B.) microplus; onde as larvas foram depositadas em vasos com Brachiaria decumbens e após migração destas para o ápice das folhas, foi aspergido solução contendo a CL99,9 (24,60mg/mL) do OE. Após 24 horas, 72,25% das larvas morreram indicando que houve estabilidade do OE quando submetido a condições de temperatura e umidade não controladas. O mecanismo de ação pelo qual o OE matou as larvas e fêmeas adultas foi investigado pelo método bioautográfico, indicando uma inibição de 3,15mg/mL do óleo essencial sobre a enzima acetilcolinesterase (AChE). Os resultados encontrados no presente experimento indicaram que o óleo essencial de E. pyriformis é uma alternativa no controle do carrapato bovino no estágio larval (parasitário) e no ciclo de vida livre (estágio não parasitário) em condições de campo.(AU)

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RESUMEN

Brazil has one of the largest commercial cattle herds in the world, which naturally coexist with an enormous number of parasitic species. Southern cattle tick, Rhipicephalus (Boophilus) microplus, is among these species, interfering with animal productivity and causing losses to the beef and dairy cattle sector. The use of chemical acaricides in the control of this mite has resulted in the emergence of resistant populations. In this sense, alternative control measures using plants as sources of botanical acaricides have shown to be effective. Eugenia pyriformis Cambess is a Brazilian plant with antioxidant and antimicrobial activity; however, there are no reports on its acaricidal activity in the literature. The present study aimed to evaluate the acaricidal and larvicidal potential of E. pyriformis leaf essential oil (EO) on southern cattle tick at different stages of the reproductive cycle. E. pyriformis leaves were collected and dried, and had their EO extracted by hydrodistillation (3h) using a modified Clevenger apparatus. Chemical analysis was performed by gas chromatography coupled with mass spectrometry (GC/MS), and 32 compounds belonging to the sesquiterpene class were identified: hydrocarbons (17.98%) and oxygenated forms (81.96%), with spathulenol (43.65%) and caryophyllene oxide (12.17%) as the most common. The EO was evaluated by the Adult Immersion Test at the concentrations (500.00 to 3.12mg/mL) in which the following parameters were measured: mortality of females (%), hatchability of eggs (%), and product efficiency (%). Larvae were assessed by the Larval Packet Test at concentrations ranging from 25.00 to 0.00004mg/mL. Lethal concentrations (LC) required for killing 50 and 99.9% of adult females and larvae were determined using Probit analysis. LC50 and LC99.9 of EO were 0.06 and 24.60mg/mL and 1,208.80 and 2,538mg/mL for larvae and adult females, respectively. Action of the EO in the free-living cycle of R. (B.) microplus larvae was another parameter assessed. To this end, the larvae were deposited in pots containing Brachiaria decumbens and, after migration to the leaf apex, a solution containing LC99.9 (24.60mg/mL) of the EO was sprayed. After 24h, 72.25% of the larvae had died, indicating stability of the EO when subjected to uncontrolled temperature and humidity conditions. The mechanism of action through which the EO killed the larvae and adult females was investigated by the Bioautographic Method, which showed inhibition of 3.15mg/mL of the EO on the acetylcholinesterase (AChE) enzyme. The results found in the present experiment indicate that E. pyriformis essential oil is an alternative in the control of southern cattle tick in the larval (parasitic) and free-living cycle (non-parasitic) stages under field conditions.(AU)

O Brasil dispõe de um dos maiores rebanhos bovinos comerciais do mundo, sendo natural que junto a esse rebanho, coexista uma enorme quantidade de espécies parasitárias; dentre estes o carrapato Rhipicephalus (Boophilus) microplus que interfere na produtividade animal, causando prejuízos à pecuária de corte e leite. A utilização de acaricidas químicos no controle deste ácaro tem causado o surgimento de populações resistentes e neste sentido, controles alternativos utilizando plantas como fontes de acaricidas botânicos têm se mostrado eficazes. Eugenia pyriformis Cambess é uma planta brasileira com atividades antioxidante e antimicrobiana, entretanto não há relatos da atividade acaricida. O objetivo do presente estudo consistiu na avaliação do potencial acaricida e larvicida do óleo essencial das folhas de E. pyriformis sobre o carrapato bovino nos diferentes estágios do ciclo reprodutivo. As folhas foram coletadas, secas e o OE extraído por hidrodestilação (3 horas) em aparelho Clevenger modificado. A análise química foi realizada por cromatografia gasosa acoplada à espectrometria de massas (CG/EM) sendo identificados 32 compostos, pertencentes à classe sesquiterpenos: hidrocarbonetos (17.98%) e oxigenados (81.96%); tendo como majoritários o spathulenol (43,65%) e caryophylene oxide (12,17%). O OE foi avaliado pelo teste de imersão de adultos nas concentrações (500,00 a 3,12mg/mL) onde foram mensurados os parâmetros: mortalidade das fêmeas (%), eclodibilidade dos ovos (%) e eficiência do produto (%). As larvas foram avaliadas pelo teste de imersão larval (Larval Packet Test) nas concentrações que variaram de 25,00 a 0,00004mg/mL. Foram determinadas as concentrações letais (CLs) necessárias para matar 50 e 99,9% das fêmeas adultas e das larvas utilizando a análise de Probitos. As CL50 e CL99,9 do OE foram (0,06 e 24,60mg/mL) para as larvas e (1.208,80 e 2.538mg/mL) para as fêmeas adultas, respectivamente. Outro parâmetro avaliado em nossa pesquisa foi mensurar a ação do OE no ciclo de vida livre das larvas de R.(B.) microplus; onde as larvas foram depositadas em vasos com Brachiaria decumbens e após migração destas para o ápice das folhas, foi aspergido solução contendo a CL99,9 (24,60mg/mL) do OE. Após 24 horas, 72,25% das larvas morreram indicando que houve estabilidade do OE quando submetido a condições de temperatura e umidade não controladas. O mecanismo de ação pelo qual o OE matou as larvas e fêmeas adultas foi investigado pelo método bioautográfico, indicando uma inibição de 3,15mg/mL do óleo essencial sobre a enzima acetilcolinesterase (AChE). Os resultados encontrados no presente experimento indicaram que o óleo essencial de E. pyriformis é uma alternativa no controle do carrapato bovino no estágio larval (parasitário) e no ciclo de vida livre (estágio não parasitário) em condições de campo.(AU)

Asunto(s)

RESUMEN

The cattle tick R. microplus is the biggest obstacle to livestock rearing in tropical countries. It is responsible for billions of dollars in losses every year, affecting meat and milk production, beef and dairy cattle, and the leather industry. The lack of knowledge and strategies to combat the tick only increases the losses, it leads to successive and uncontrolled applications of acaricides, favouring the selection of strains resistant to commercially available chemical treatments. In this paper, we tested 3­bromopyruvate (3­BrPA), an alkylating agent with a high affinity for cysteine residues, on the R. microplus metabolism. We found that 3-BrPA was able to induce cell death in an assay using BME26 strain cell cultures derived from embryos, it was also able to reduce cellular respiration in developing embryos. 3-BrPA is a nonspecific inhibitor, affecting enzymes of different metabolic pathways in R. microplus. In our experiments, we demonstrated that 3-BrPA was able to affect the glycolytic enzyme hexokinase, reducing its activity by approximately 50%; and it strongly inhibited triose phosphate isomerase, which is an enzyme involved in both glycolysis and gluconeogenesis. Also, the mitochondrial respiratory chain was affected, NADH cytochrome c reductase (complex I-III) and succinate cytochrome c reductase (complex II-III) were strongly inhibited by 3-BrPA. Glutamate dehydrogenase was also affected by 3-BrPA, showing a gradual inhibition of activity in all the 3-BrPA concentrations tested. Altogether, these results show that 3-BrPA is a harmful compound to the tick organism.

Asunto(s)

RESUMEN

ABSTRACT: Brazil has one of the largest commercial cattle herds in the world, which naturally coexist with an enormous number of parasitic species. Southern cattle tick, Rhipicephalus (Boophilus) microplus, is among these species, interfering with animal productivity and causing losses to the beef and dairy cattle sector. The use of chemical acaricides in the control of this mite has resulted in the emergence of resistant populations. In this sense, alternative control measures using plants as sources of botanical acaricides have shown to be effective. Eugenia pyriformis Cambess is a Brazilian plant with antioxidant and antimicrobial activity; however, there are no reports on its acaricidal activity in the literature. The present study aimed to evaluate the acaricidal and larvicidal potential of E. pyriformis leaf essential oil (EO) on southern cattle tick at different stages of the reproductive cycle. E. pyriformis leaves were collected and dried, and had their EO extracted by hydrodistillation (3h) using a modified Clevenger apparatus. Chemical analysis was performed by gas chromatography coupled with mass spectrometry (GC/MS), and 32 compounds belonging to the sesquiterpene class were identified: hydrocarbons (17.98%) and oxygenated forms (81.96%), with spathulenol (43.65%) and caryophyllene oxide (12.17%) as the most common. The EO was evaluated by the Adult Immersion Test at the concentrations (500.00 to 3.12mg/mL) in which the following parameters were measured: mortality of females (%), hatchability of eggs (%), and product efficiency (%). Larvae were assessed by the Larval Packet Test at concentrations ranging from 25.00 to 0.00004mg/mL. Lethal concentrations (LC) required for killing 50 and 99.9% of adult females and larvae were determined using Probit analysis. LC50 and LC99.9 of EO were 0.06 and 24.60mg/mL and 1,208.80 and 2,538mg/mL for larvae and adult females, respectively. Action of the EO in the free-living cycle of R. (B.) microplus larvae was another parameter assessed. To this end, the larvae were deposited in pots containing Brachiaria decumbens and, after migration to the leaf apex, a solution containing LC99.9 (24.60mg/mL) of the EO was sprayed. After 24h, 72.25% of the larvae had died, indicating stability of the EO when subjected to uncontrolled temperature and humidity conditions. The mechanism of action through which the EO killed the larvae and adult females was investigated by the Bioautographic Method, which showed inhibition of 3.15mg/mL of the EO on the acetylcholinesterase (AChE) enzyme. The results found in the present experiment indicate that E. pyriformis essential oil is an alternative in the control of southern cattle tick in the larval (parasitic) and free-living cycle (non-parasitic) stages under field conditions.

RESUMO: O Brasil dispõe de um dos maiores rebanhos bovinos comerciais do mundo, sendo natural que junto a esse rebanho, coexista uma enorme quantidade de espécies parasitárias; dentre estes o carrapato Rhipicephalus (Boophilus) microplus que interfere na produtividade animal, causando prejuízos à pecuária de corte e leite. A utilização de acaricidas químicos no controle deste ácaro tem causado o surgimento de populações resistentes e neste sentido, controles alternativos utilizando plantas como fontes de acaricidas botânicos têm se mostrado eficazes. Eugenia pyriformis Cambess é uma planta brasileira com atividades antioxidante e antimicrobiana, entretanto não há relatos da atividade acaricida. O objetivo do presente estudo consistiu na avaliação do potencial acaricida e larvicida do óleo essencial das folhas de E. pyriformis sobre o carrapato bovino nos diferentes estágios do ciclo reprodutivo. As folhas foram coletadas, secas e o OE extraído por hidrodestilação (3 horas) em aparelho Clevenger modificado. A análise química foi realizada por cromatografia gasosa acoplada à espectrometria de massas (CG/EM) sendo identificados 32 compostos, pertencentes à classe sesquiterpenos: hidrocarbonetos (17.98%) e oxigenados (81.96%); tendo como majoritários o spathulenol (43,65%) e caryophylene oxide (12,17%). O OE foi avaliado pelo teste de imersão de adultos nas concentrações (500,00 a 3,12mg/mL) onde foram mensurados os parâmetros: mortalidade das fêmeas (%), eclodibilidade dos ovos (%) e eficiência do produto (%). As larvas foram avaliadas pelo teste de imersão larval (Larval Packet Test) nas concentrações que variaram de 25,00 a 0,00004mg/mL. Foram determinadas as concentrações letais (CLs) necessárias para matar 50 e 99,9% das fêmeas adultas e das larvas utilizando a análise de Probitos. As CL50 e CL99,9 do OE foram (0,06 e 24,60mg/mL) para as larvas e (1.208,80 e 2.538mg/mL) para as fêmeas adultas, respectivamente. Outro parâmetro avaliado em nossa pesquisa foi mensurar a ação do OE no ciclo de vida livre das larvas de R.(B.) microplus; onde as larvas foram depositadas em vasos com Brachiaria decumbens e após migração destas para o ápice das folhas, foi aspergido solução contendo a CL99,9 (24,60mg/mL) do OE. Após 24 horas, 72,25% das larvas morreram indicando que houve estabilidade do OE quando submetido a condições de temperatura e umidade não controladas. O mecanismo de ação pelo qual o OE matou as larvas e fêmeas adultas foi investigado pelo método bioautográfico, indicando uma inibição de 3,15mg/mL do óleo essencial sobre a enzima acetilcolinesterase (AChE). Os resultados encontrados no presente experimento indicaram que o óleo essencial de E. pyriformis é uma alternativa no controle do carrapato bovino no estágio larval (parasitário) e no ciclo de vida livre (estágio não parasitário) em condições de campo.

RESUMEN

Rhipicephalus (Boophilus) microplus infestation is responsible for significant economic losses in cattle industry. The use of acaricides at strategic times and selection of resistant animals can minimize economic losses. This study aimed to determine the anatomical distribution and population dynamics of R. microplus in the municipality of Óleo, state of São Paulo. This study was conducted using eight male cattle, crossbred zebu-taurine (in accordance with the regional herd). Female R. (B.) microplus, greater than 4 mm, present in the right side of the animals were counted between April 2012 and March 2013. The highest tick number per animal was noted in October (128.25), and the lowest in April (35.5), with three infestation peaks during the study, in May, October, and December, which were influenced by the minimum and maximum mean temperature and rainfall. Among the cranio-caudal regions (anterior,median, and posterior), the posterior had the highest mean tick number, and the anterior had the lowest. The minimum temperature, rainfall, and solar radiation interfered with infestation of dorsoventral regions: in cold months, the lowest infestations were found in the mixed area (ear and tail); in the warm months, in the high region (head, neck, upper ribs, flank, and rump). The lower region (dewlap, cranial limb, lower ribs, abdomen, prepuce, scrotum, and lower limb) always had the highest mean tick number.The tick numbers of the caudal limb and crotch showed strong correlation with the total tick number (+ 0.88 and + 0.70, respectively). These data, grouped according to median, posterior, and crotch regions, showed a stronger correlation with the total tick number (+ 0.96, + 0.90, and + 0.70, respectively).(AU)

A infestação pelo Rhipicephalus (Boophilus) microplus é responsável por significativas perdas econômicas na pecuária bovina. O uso de acaricidas de forma estratégica e a seleção de animais mais resistentes podem minimizar os prejuízos econômicos. O objetivo deste estudo foi determinar a distribuição anatômica e a dinâmica populacional do carrapato em bovinos do município de Óleo, SP. O estudo foi conduzido com 08 bovinos machos, mestiços zebu-taurino (conforme rebanho regional). Foram contadas as fêmeas de R. (B.) microplus, maiores que 4 mm, existentes no lado direito do animal, a cada 4 semanas, no período entre abril de 2012 e março de 2013. Obteve-se o maior número de carrapatos por animal em outubro (128,25), e o menor em abril (35,5), com a existência de três picos de infestação, sendo eles nos meses de maio, outubro e dezembro. Verificou-se a existência de três gerações anuais de carrapatos, que foram influenciadas pela precipitação pluviométrica e temperatura média, mínima e máxima. Das regiões Crânio-caudal (anterior, mediana e posterior), a posterior obteve o maior número médio de carrapatos e a anterior o menor. A temperatura mínima, a pluviosidade e a radiação solar interferiram nas infestações das regiões Dorso-ventral, nos meses frios, as menores infestações foram encontradas na área mista (orelha e cauda) e nos meses quentes na alta (cabeça, pescoço, costado alto, flanco e garupa). A região baixa (barbela, membro cranial, costado baixo, ventre,prepúcio, membro caudal e bolsa escrotal) se manteve sempre com a maior média. Das diferentes regiões anatômicas estabelecidas, o número de carrapatos do membro caudal e entrepernas mostraram ter forte correlação com o total, + 0,88 e + 0,70, respectivamente. Esses mesmos dados, agrupados segundo regiões previamente estabelecidas, obtiveram correlação mais forte com o total de carrapatos, sendo + 0,96 (mediana), + 0,90 (posterior) e + 0,70 (entrepernas).(AU)

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RESUMEN

The tick genus Ripicephalus (Boophilus), particularly R. microplus, is one of the most important ectoparasites that affects livestock health and considered an epidemiological risk because it causes significant economic losses due, mainly, to restrictions in the export of infested animals to several countries. Its spatial distribution has been tied to environmental factors, mainly warm temperatures and high relative humidity. In this work, we integrated a dataset consisting of 5843 records of Rhipicephalus spp., in Mexico covering close to 50 years to know which environmental variables mostly influence this ticks' distribution. Occurrences were georeferenced using the software DIVA-GIS and the potential current distribution was modelled using the maximum entropy method (Maxent). The algorithm generated a map of high predictive capability (Area under the curve = 0.942), providing the various contribution and permutation importance of the tested variables. Precipitation seasonality, particularly in March, and isothermality were found to be the most significant climate variables in determining the probability of spatial distribution of Rhipicephalus spp. in Mexico (15.7%, 36.0% and 11.1%, respectively). Our findings demonstrate that Rhipicephalus has colonized Mexico widely, including areas characterized by different types of climate. We conclude that the Maxent distribution model using Rhipicephalus records and a set of environmental variables can predict the extent of the tick range in this country, information that should support the development of integrated control strategies.

Asunto(s)

RESUMEN

Rhipicephalus (Boophilus) microplus infestation is responsible for significant economic losses in cattle industry. The use of acaricides at strategic times and selection of resistant animals can minimize economic losses. This study aimed to determine the anatomical distribution and population dynamics of R. microplus in the municipality of Óleo, state of São Paulo. This study was conducted using eight male cattle, crossbred zebu-taurine (in accordance with the regional herd). Female R. (B.) microplus, greater than 4 mm, present in the right side of the animals were counted between April 2012 and March 2013. The highest tick number per animal was noted in October (128.25), and the lowest in April (35.5), with three infestation peaks during the study, in May, October, and December, which were influenced by the minimum and maximum mean temperature and rainfall. Among the cranio-caudal regions (anterior,median, and posterior), the posterior had the highest mean tick number, and the anterior had the lowest. The minimum temperature, rainfall, and solar radiation interfered with infestation of dorsoventral regions: in cold months, the lowest infestations were found in the mixed area (ear and tail); in the warm months, in the high region (head, neck, upper ribs, flank, and rump). The lower region (dewlap, cranial limb, lower ribs, abdomen, prepuce, scrotum, and lower limb) always had the highest mean tick number.The tick numbers of the caudal limb and crotch showed strong correlation with the total tick number (+ 0.88 and + 0.70, respectively). These data, grouped according to median, posterior, and crotch regions, showed a stronger correlation with the total tick number (+ 0.96, + 0.90, and + 0.70, respectively).

A infestação pelo Rhipicephalus (Boophilus) microplus é responsável por significativas perdas econômicas na pecuária bovina. O uso de acaricidas de forma estratégica e a seleção de animais mais resistentes podem minimizar os prejuízos econômicos. O objetivo deste estudo foi determinar a distribuição anatômica e a dinâmica populacional do carrapato em bovinos do município de Óleo, SP. O estudo foi conduzido com 08 bovinos machos, mestiços zebu-taurino (conforme rebanho regional). Foram contadas as fêmeas de R. (B.) microplus, maiores que 4 mm, existentes no lado direito do animal, a cada 4 semanas, no período entre abril de 2012 e março de 2013. Obteve-se o maior número de carrapatos por animal em outubro (128,25), e o menor em abril (35,5), com a existência de três picos de infestação, sendo eles nos meses de maio, outubro e dezembro. Verificou-se a existência de três gerações anuais de carrapatos, que foram influenciadas pela precipitação pluviométrica e temperatura média, mínima e máxima. Das regiões Crânio-caudal (anterior, mediana e posterior), a posterior obteve o maior número médio de carrapatos e a anterior o menor. A temperatura mínima, a pluviosidade e a radiação solar interferiram nas infestações das regiões Dorso-ventral, nos meses frios, as menores infestações foram encontradas na área mista (orelha e cauda) e nos meses quentes na alta (cabeça, pescoço, costado alto, flanco e garupa). A região baixa (barbela, membro cranial, costado baixo, ventre,prepúcio, membro caudal e bolsa escrotal) se manteve sempre com a maior média. Das diferentes regiões anatômicas estabelecidas, o número de carrapatos do membro caudal e entrepernas mostraram ter forte correlação com o total, + 0,88 e + 0,70, respectivamente. Esses mesmos dados, agrupados segundo regiões previamente estabelecidas, obtiveram correlação mais forte com o total de carrapatos, sendo + 0,96 (mediana), + 0,90 (posterior) e + 0,70 (entrepernas).

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RESUMEN

The in vitro acaricide activity of hexane, ethyl acetate and ethanol extracts of Ocotea aciphylla leaves was investigated by means of an immersion tests using Rhipicephalus (Boophilus) microplus engorged females and larvae. All extracts were shown effective against the different stages of the parasite, and the ethanol extract (50mg/mL concentration) was the most active (more than 90% efficacy in both assays). The ethanolic extract was fractionated using column chromatography with silica gel as stationary phase to furnish several fractions that were tested against larvae of R. (B.) microplus. Three fractions showed high acaricidal activity (50mg/mL), causing between 84.2% and 100% mortality of the larvae. The anticholinesterase effect of these fractions was determined spectrophotometrically using a microtiter assay. The chemical investigation of the active fractions led to the characterization of terpenoids (cadalene 1 and squalene 2), a phenylpropanoid (dillapiole 3) and a phenolic mixture containing five proanthocyanidins (4-8) and a flavonoid(vitexin-2"-O-rhamnoside 9). Our findings suggest that the O. aciphylla has potent acaricidal activity in vitro against R. (B.) microplus, and that different secondary metabolites are responsible for this effect.

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RESUMEN

Con el objetivo de evaluar la eficacia de la asociación entre el piretroide Cipemetrina y los oganofosforados Fentión y Clorpirifos frente a la garrapata Rhipicephalus (Boophilus) microplus, en un rebaño naturalmente infestado en el estado de Mato Grosso, fueron evaluados 24 animales con infestación media de 33,11 teleóginas. Luego de la división aleatoria de los animales en dos grupos, se utilizó la formulación tópica por pulverización FC- 30 (Orofino Salud Animal, SP, Brasil) en la mitad de los animales, mientras que la otra mitad fue utilizada como grupo control. Se realizaron recuentos de las garrapatas tres días antes del tratamiento y semanalmente luego de la aplicación del producto (eficacia terapéutica). También se analizó la reinfestación de estos animales (eficacia preventiva). Los perfiles terapéuticos y preventivos indican que la formulación controla el parasitismo por R. (B.) microplus en bovinos por lo menos 21 días después del tratamiento.

This study aimed to evaluate the efficacy of an association of pyrethroids and organophosphate formula in the Rhipicephalus (Boophilus) microplus control in a natural infested cattle from Mato Grosso State. They were evaluated 24 animals with 33.11 engorged female ticks of medium infestation. After a randomized division in two groups, 12 animals were treated with the formulation FC-30 (Ourofino Animal Health, SP, Brasil) and the other half was the controlled group. After treatment, they were made week counts (therapeutic efficacy), as well the reinfestation (preventive efficacy). Therapeutic and preventive profiles showed efficacy of the formulation in the control of R. (B.) microplus in the tested cattle for, at least, 21 days after treatment.

Com o objetivo de avaliar a eficácia da associação do piretróide Cipermetrina e dos organofosforados Fenthion e Clorpirifós frente ao carrapato Rhipicephalus (Boophilus) microplus em um rebanho naturalmente infestado no estado de Mato Grosso, foram avaliados 24 animais com infestação média de 33,11 teleóginas. Após divisão randomizada dos animais em dois grupos, foi utilizada a formulação tópica por pulverização FC-30 (Ourofino Saúde Animal, SP, Brasil) na metade dos animais, enquanto que a outra metade foi utilizada como grupo controle. Foram realizadas contagens dos carrapatos três dias antes do tratamento, e semanalmente após a aplicação do produto (eficácia terapêutica), bem como avaliando sua reinfestação (eficácia preventiva). Perfis terapêuticos e preventivos indicam que a formulação controla o parasitismo por R. (B.) microplus em bovinos por pelo menos 21 dias após o tratamento.

Asunto(s)

RESUMEN

Con el objetivo de evaluar la eficacia de la asociación entre el piretroide Cipemetrina y los oganofosforados Fentión y Clorpirifos frente a la garrapata Rhipicephalus (Boophilus) microplus, en un rebaño naturalmente infestado en el estado de Mato Grosso, fueron evaluados 24 animales con infestación media de 33,11 teleóginas. Luego de la división aleatoria de los animales en dos grupos, se utilizó la formulación tópica por pulverización FC- 30 (Orofino Salud Animal, SP, Brasil) en la mitad de los animales, mientras que la otra mitad fue utilizada como grupo control. Se realizaron recuentos de las garrapatas tres días antes del tratamiento y semanalmente luego de la aplicación del producto (eficacia terapéutica). También se analizó la reinfestación de estos animales (eficacia preventiva). Los perfiles terapéuticos y preventivos indican que la formulación controla el parasitismo por R. (B.) microplus en bovinos por lo menos 21 días después del tratamiento.(AU)

This study aimed to evaluate the efficacy of an association of pyrethroids and organophosphate formula in the Rhipicephalus (Boophilus) microplus control in a natural infested cattle from Mato Grosso State. They were evaluated 24 animals with 33.11 engorged female ticks of medium infestation. After a randomized division in two groups, 12 animals were treated with the formulation FC-30 (Ourofino Animal Health, SP, Brasil) and the other half was the controlled group. After treatment, they were made week counts (therapeutic efficacy), as well the reinfestation (preventive efficacy). Therapeutic and preventive profiles showed efficacy of the formulation in the control of R. (B.) microplus in the tested cattle for, at least, 21 days after treatment.(AU)

Com o objetivo de avaliar a eficácia da associação do piretróide Cipermetrina e dos organofosforados Fenthion e Clorpirifós frente ao carrapato Rhipicephalus (Boophilus) microplus em um rebanho naturalmente infestado no estado de Mato Grosso, foram avaliados 24 animais com infestação média de 33,11 teleóginas. Após divisão randomizada dos animais em dois grupos, foi utilizada a formulação tópica por pulverização FC-30 (Ourofino Saúde Animal, SP, Brasil) na metade dos animais, enquanto que a outra metade foi utilizada como grupo controle. Foram realizadas contagens dos carrapatos três dias antes do tratamento, e semanalmente após a aplicação do produto (eficácia terapêutica), bem como avaliando sua reinfestação (eficácia preventiva). Perfis terapêuticos e preventivos indicam que a formulação controla o parasitismo por R. (B.) microplus em bovinos por pelo menos 21 dias após o tratamento.(AU)

Asunto(s)