Palavras-chave: controle de carrapatos, carrapaticidas,Boophilus microplus, bovinos. ABSTRACT In the southern region of Rio Grande do Sul State, European cattle represent the most important stock used for meat and milk production. This region is considered a marginal area for the occurrence of the tick
This study aimed to verify the influence of bovine genetic resistance on biological traits of the Rhipicephalus (Boophilus) microplus tick. Genetic resistance or susceptibility was determined according to breeding values for tick counts, predicted using a dataset of 9007 Hereford and Braford (Hereford×Zebu) bovines naturally infested and raised under extensive production systems in southern Brazil. From a total of 974 Braford heifers born in 2008, 20 were classified as genetically tick-resistant and 20 classified as genetically tick-susceptible, and used to obtain the ticks samples used in this study. The 40 heifers were exposed to four subsequent artificial infestations with approximately 20,000 larvae at 14-day intervals. From the 19th to 23rd day of each infestation tick counts were performed on the left body side of the heifers. Engorged ticks were manually collected on the day of highest observed burden after each infestation. Tick counts on susceptible heifers were 5.5, 10.5, 11.1 and 6.9 times larger than on resistant heifers, respectively, after the first, second, third and fourth artificial infestations. In the third infestation, ticks from resistant heifers showed lower egg production index (P<0.0001) than ticks from susceptible heifers. In the fourth infestation, ticks from susceptible group showed higher egg mass weight (P<0.05) and nutrient index (P<0.0001) than ticks from resistant heifers. Tick initial weights showed a positive association with egg production index in susceptible heifers (P<0.05) and a negative association in the resistant group (P<0.05), suggesting a host defense mechanism that reduces the conversion efficiency of ingested blood to eggs in engorged ticks from resistant cattle. This shows that bovine genetic tick resistance, in addition to affecting the number of ticks carried by the animals, also affected the egg mass weight, egg production and nutrient indexes of ticks. The results of the present study imply that the selection of resistant animals could be used as a strategic tool for tick control in production systems, reducing infestation levels on cattle and environment.
In the southern region of Rio Grande do Sul, cattle become infested with Rhipicephalus (B.) microplus mainly between October and April due to the climatic conditions. In addition to knowing its life cycle, knowledge of parasite's epidemiology is essential to establish management strategies. Epidemiological studies on resistance to acaricides in Rio Grande do Sul as well as in the rest of Brazil are scarce. Moreover, the large geographical area and the structural deficiency with respect to the use and access to databases make reliable data difficult to obtain. The present study surveyed the perception by cattle breeders in the southern region of Rio Grande do Sul in regards of identification of R. (B.) microplus populations that are difficult to manage using acaricides, as well as the risk factors for the selection of resistant tick populations. Tick management data on beef cattle in 85 properties of seven municipalities were collected. The results revealed that the difficulty in tick management correlated positively with levels of education of the farm owners (up to elementary school, OR = 3.67 and p = 0.01) and with the yearly number of acaricide applications (over four, with OR = 4.05 and p= 0.006). These results also suggest that properties with more than 100 beef cattle under extensive farming conditions in the southern region of Rio Grande do Sul show characteristics that may contribute to longer acaricide lifetimes as compared to other regions in the Country.
Palavras chave-adicionaisAlphitobius diaperinus. Ambiência. Controle de praga.resUMo O Brasil é o maior exportador e o terceiro maior produtor mundial de carne de frango, sendo a atividade geradora de grande quantidade de resíduo chamado de cama de frango. Este resíduo gera condições favoráveis para o desenvolvimento do besouro Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae), conhecido como cascudinho, sendo esse considerado a principal praga da avicultura, e afeta a produção avícola em todo o mundo. Seu controle é considerado difícil, sendo comumente empregadas substâncias piretróides e organofosforadas, apesar de não eficientes. Na busca pelo controle alternativo do inseto, vários métodos aditivos e inseticidas naturais vêm sendo testados. Contudo, na prática entomológica, substâncias com elevada pressão de vapor a fim de se produzir gases tóxicos são utilizadas para fixação dos insetos. Assim, em outubro de 2015, avaliou-se o álcool etílico PA para o controle de A. diaperinus em cama de frango. As unidades experimentais foram representadas por garrafas plásticas tipo pet cortadas, onde foram colocadas 100 g de cama de frango, acrescidos de 20 insetos adultos e 135 larvas, cada uma. Os tratamentos foram constituídos pela aplicação de álcool no volume de 1, 2,5, 5, 7,5 e 10 mL e sua diluição com água (1:1) sendo aplicado igual volume. Simularam-se dois ambientes, sendo um aberto (com telas contendo os insetos) e um fechado (recipiente amostral fechado com a porção previamente cortada da garrafa pet). Nas parcelas foram mantidas a temperatura de 28,5 ± 2 ºC e UR de 51,0 ± 2%, feito seis repetições por tratamento. A quantidade de 2,5 mL (2,5% v/p) de álcool gerou 100% de mortalidade de adultos e larvas nas amostras fechadas, sendo necessário o dobro do volume no sistema aberto. Para a diluição álcool-água (1:1) o controle de 100% foi obtido com o dobro das quantidades relatadas anteriormente em relação aos respectivos tratamentos.inforMation Cronología del artículo. Recibido/sUMMarYBrazil is the third largest producer of chicken meat in the world, resulting in the production of a large amount of waste called chicken litter. This residue generates favorable conditions for the development of the beetle Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae), known as cascudinho, which is considered the main pest of poultry farming, affecting poultry production worldwide. Its control is considered difficult, and pyrethroid and organophosphorous substances are commonly used, although they are not efficient. In the search for alternative insect control, several natural insecticidal and insecticidal methods have been tested. However, in the entomological practice, substances with high vapor pressure in order to produce toxic gases are used for insect fixation. Thus, in October 2015, ethyl alcohol PA was tested with the aim of controlling A. diaperinus in chicken litter. The experimental units were represented by cut plastic pet bottles, where 100 g of were poultry litter added, with 20 adult insects and ...
Field samples of Rhipicephalus (Boophilus) microplus from the state of Rio Grande do Sul, Brazil, were assessed using the following methods: larval packet test (LPT), larval immersion test (LIT) and syringe immersion test (SIT). The following parameters were determined for each population and for the Mozo susceptible reference strain: lethal concentration for 50% (LC 50 ) with its 95% confidence interval (95% CI), regression line slope and resistance ratio (RR). Using the LPT, only one population was susceptible to amitraz, presenting a RR of 1.9. Using the same technique, the other populations presented RRs of between 92.9 and 3445.8 and were considered resistant. The LC 50 of the Mozo strain calculated using the LPT, LIT and SIT was 2.9, 27.3, and 52.7 µg/mL, respectively. In general, a good fit to the probit statistical model was only achieved using the LPT. The results obtained in this study impair recommendations for using the LIT and SIT to diagnose amitraz resistance in R. (B.) microplus populations. Additional studies are required to improve the sensitivity of these tests in relation to the LPT.Keywords: Rhipicephalus (Boophilus) microplus, amitraz, bioassays, resistance diagnosis. ResumoAmostras de Rhipicephalus (Boophilus) microplus coletadas à campo no Rio Grande do Sul, Brasil, foram analisadas pelos seguintes métodos: teste do pacote de larvas (TPL), teste de imersão de larvas (TIL) e teste de imersão em seringas (TIS). Os seguintes parâmetros foram determinados para cada população e para a amostra referência suscetível Mozo: concentração letal para 50% (CL 50 ) e seu intervalo de confiança de 95% (IC95%), inclinação da reta de regressão e os fatores de resistência (FR). Pelo TPL, apenas uma população foi sensível ao amitraz, com FR de 1,9. Utilizando a mesma técnica, as outras amostras apresentaram FR entre 92,9 e 3445,8 sendo consideradas resistentes. As CL 50 da cepa Mozo calculadas por meio do TPL, TIL e TIS foram 2,9, 27,3 e 52,7 µg/mL, respectivamente. De forma geral, a adequação ao modelo estatístico de probitos só foi alcançada com o uso do TPL. Os resultados obtidos no presente estudo limitam a recomendação de uso do TIL e TIS para diagnóstico de resistência ao amitraz em populações de R. (B.) microplus. Estudos adicionais são necessários para aprimorar a sensibilidade destes testes em relação ao LPT.Palavras-chave: Rhipicephalus (Boophilus) microplus, amitraz, bioensaio, diagnóstico de resistência.
ABSTRACT:The Rhipicephalus (Boophilus) microplus is responsible for considerable losses in Brazilian cattle. The control of such parasites has been done mainly with the use of acaricides, and the isopathy is an alternative. The objective of this work is to analyze the efficiency of the use of isopathy as an alternative tool to control the cattle tick. We used 18 cows of the European race, kept in extensive livestock system in the municipality of Canguçu, Rio Grande do Sul, Brazil. The animals were divided into control group (Lot A) and group treated with isopathy (Lot B). Mineral salt was used as a vehicle for the administration of isopathy, Lot A received mineral salt with placebo (sugar) and Lot B received mineral salt with isopathy. The animals were artificially infested with 10 thousan larvae of R. (B.) microplus, and in the days 20, 21 and 22 post-infestation engorged females were counted and collected. The ticks from each batch were randomly divided into nine groups of ten subjects each for analysis of biological parameters and subsequent calculation of the Nutritional Index and the Effectiveness Reproductive Index. For comparison of average engorged females from each group were employed ANOVA and LSD Test. The animals treated with isopathy showed a 53.4% reduction in the average number of ticks when compared with the untreated group (p = 0.001). As for biological standards, there was no statistical difference. It is concluded that the use of isopathy was able to reduce infestation of R. (B.) microplus, showing up as a promising alternative to control this ticks.KEYWORDS: Materia medica; homeopathy; biotherapics. RESUMO:O Rhipicephalus (Boophilus) microplus é responsável por consideráveis perdas na pecuária brasileira. O controle desse parasita tem sido feito, principalmente, com o uso de carrapaticidas, sendo os isoterápicos uma alternativa para seu combate. Objetivou-se neste trabalho analisar a eficiência da utilização da isopatia como ferramenta de controle alternativo do carrapato-do-boi. Foram utilizadas 18 fêmeas bovinas de raça europeia, mantidas em sistema de pecuária extensiva, no município de Canguçu, Rio Grande do Sul. Os animais foram divididos em grupo controle (Lote A) e grupo tratado com isoterápico (Lote B). O sal mineral foi utilizado como veículo para a administração da isopatia, sendo que o Lote A recebeu sal mineral com placebo (açúcar) e o Lote B sal mineral com isopatia. Os animais foram infestados artificialmente com 10 mil larvas de R. (B.) microplus, e no 20º, 21º e 22º dias pós-infestação, foram realizadas contagem e coleta de fêmeas ingurgitadas. As teleóginas de cada lote foram divididas ao acaso em nove grupos de dez indivíduos para análise dos parâmetros biológicos e posterior cálculo do Índice Nutricional e Índice de Eficácia Reprodutiva. Para comparação da média de teleóginas de cada grupo, foi empregada análise de variân-cia e Teste LSD. Os bovinos tratados com isopatia apresentaram uma redução de 53,4% do número médio de teleóginas, quando comparados com o grupo não trata...
O objetivo deste estudo foi avaliar o efeito in vitro do extrato aquoso, extrato hidroalcoólico, extrato hidroalcoólico concentrado e óleo essencial de citronela (Cymbopogon wynterianus) sobre larvas e teleóginas de Riphicephalus (Boophilus) microplus. Os extratos foram preparados de folhas secas de citronela. Para realizar os testes com as larvas foram utilizadas seis concentrações (3,12; 6,25; 12,5; 25; 50 e 100%) de cada extrato, além dos grupos controle. A sensibilidade das teleóginas aos extratos foi testada utilizando o Teste de Drummond (biocarrapaticidograma), sendo utilizados no teste: extrato aquoso a 100%, extrato hidroalcoólico a 100%, extrato hidroalcoólico concentrado a 50% e óleo essencial nas concentrações de 6,25; 12,5 e 25%. As teleóginas também foram testadas frente a três produtos comerciais disponíveis no mercado. Os resultados indicaram que a citronela tem ação acaricida, principalmente, quando utilizada na forma de óleo essencial, pois a partir da concentração de 12,5% foi capaz de causar 100% de mortalidade larval, e a 25% demonstrou índice de eficácia de 100% no teste com teleóginas, resultado superior ao observado com os produtos comerciais testados. Conclui-se que citronela, na forma de óleo essencial, foi eficaz no controle de Riphicephalus (Boophilus) microplus nas condições deste experimento.
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