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Pesq. Vet. Bras. 33(3):319-325, março 2013 319 RESUMO.-[Aspectos clínicos e dinâmica de parasitoses auriculares em bovinos da raça Gir.] Avaliou-se a dinâ-mica da infestação auricular causada por Rhabditis spp. e por Raillietia spp., relacionando-a com a idade dos animais, com a intensidade dos sinais clínicos e com os fatores climáticos. Utilizaram-se 64 bovinos Gir, distribuídos em três grupos: GA -23 bezerros de quatro a seis meses de idade, GB -18 bezerros de sete a 12 meses e GC -23 novilhas de 13 a 33 meses. Foram feitas cinco coletas a cada três meses. A secreção auricular foi coletada utilizando o método de lavagem auricular na orelha direita e um swab na orelha esquerda. Sixty-four Gir cattle were distributed into three groups: GA -23 calves with 4 to 6 months of age; GB -18 calves with 7 to 12 months of age; and GC -23 heifers with 13 to 33 months of age. Five samplings, defined as S1, S2, S3, S4 and S5 were performed every three months from August 2008 to August 2009. The ear secretion was collected using the auricular washing method for the right ear and a swab for the left ear. A clinical assessment of the animals was performed, and they were classified according to the presence and severity of otitis. The highest relative frequency of rhabditosis was 52.2% in GC at the last sampling. In the first sampling, 42.2% of the animals were infested by Raillietia spp. The older cattle were more susceptible to infestations by both parasites. No correlation of Rhabditis spp. and Raillietia spp. parasitism with climate factors was found. The results showed that both parasites could infest Gir cattle, and in most cases, there was no co-infestation. Only older animals parasitized by the nematode showed clinical signs of the disease. maior frequência relativa da rhabditiose encontrada foi de 52,2%, no GC na ultima coleta. Na primeira coleta, 42,2% dos animais estavam infestados pela Raillietia spp. Os bovinos mais velhos foram mais suscetíveis às infestações de ambos os parasitos. Não foi encontrada correlação entre o parasitismo por Rhabditis spp. e por Raillietia spp. e os fatores climáticos. Concluiu-se que ambos os parasitas podem infestar bovinos da raça Gir e na maioria dos casos, não ocorreram infestações simultâneas. Apenas os animais mais velhos, parasitados pelo nematóide, apresentaram sinais clínicos da doença.

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ResumoO presente trabalho foi realizado com o objetivo de caracterizar o controle dos endoparasitos em rebanhos bovinos do Estado de Minas Gerais. Foram aplicados questionários em 1.304 propriedades rurais, dos quais 1.289 foram validados e utilizados no estudo. As propriedades localizavam-se em 555 municípios inseridos nas 66 microrregiões do Estado de Minas Gerais e foram selecionados por amostragem aleatória. Os entrevistados foram questionados quanto ao perfil sócioeconômico, características de produção e de manejo sanitário da população bovina de cada propriedade, além das atitudes tomadas para o combate dos endoparasitos. Os resultados demonstraram que as diversas práticas de controle das verminoses recomendadas para os rebanhos bovinos são desconhecidas pela maioria dos pecuaristas.Palavras-chave: Atitudes, pecuaristas, endoparasitos, bovinos. AbstractThis study aimed to characterize the cattle endoparasites control in Minas Gerais State. Questionnaires were applied in 1,304 farms and 1,289 were validated and used in this study. The farms were located at 555 municipalities inserted in 66 Minas Gerais micro-regions and were selected by random sampling. The interviewees were asked about socioeconomic profile, production characteristics and cattle sanitary management of each farm, and attitudes to control the endoparasites. Results showed that the parasites control practices recomemended to cattle are unknown to most of the farmers.

Population explosions of the stable fly (Stomoxys calcitrans) have become a serious concern for livestock producers near sugarcane mills in some regions of Brazil due to the insect’s massive reproduction on sugarcane byproducts and waste. Despite the limited efficiency of insecticides for controlling stable fly outbreaks, producers still rely on chemical control to mitigate the alarming infestations in affected areas. This study evaluated the susceptibility of S. calcitrans populations to cypermethrin in the state of Mato Grosso do Sul, Brazil. Stable flies were tested from three field populations and two colonies, established from flies previously collected at sugarcane mills. Wild flies were collected with Nzi traps in areas of sugarcane plantations. Both wild and colonized flies were exposed to eleven concentrations of cypermethrin in impregnated filter paper bioassays. All the populations proved to be resistant to cypermethrin, with resistance factors among field populations ranging from 6.8 to 38.6. The intensive use of insecticides has led to the development of pyrethroid resistance in stable fly populations in the proximities of sugarcane mills in the state of Mato Grosso do Sul.

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The horn fly, Haematobia irritans irritans (L., 1758) (Diptera: Muscidae), is an important pest that causes significant economic losses to the livestock industry, but insecticide resistance in horn fly populations has made horn fly control increasingly difficult to achieve. In this study, we developed a multiplex polymerase chain reaction (PCR) assay to simultaneously detect target site resistance to pyrethroids (kdr mutation), organophosphates (G262A acetylcholinesterase mutation), and cyclodienes (Rdl mutation) and used the new procedure to follow the progression of these three mutations after exposure to different insecticide pressure. We assayed flies collected at the Macon Ridge research station, Winnsboro, LA, from 2008 to 2012. The multiplex PCR showed robust results in all our assays. The kdr mutation remained at high frequencies during all years, even after 4 yr with no use of pyrethroids. The G262A acetylcholinesterase mutation fluctuated from 7.5 to 23.8% during the studied years, while the Rdl mutation was rare in 2008, 2009, and June 2010, and then significantly increased after the first use of endosulfan. The possibility of screening for all the known target site resistance mutations in a single PCR reaction makes the multiplex PCR a useful and affordable tool that can be used to help diagnose insecticide resistance.