RESUMO

The horn fly, Haematobia irritans, is a bovine ectoparasite that causes large losses to cattle breeders, through lower meat and milk production and hide damage. Currently, the control of this parasite is mainly through chemicals. However, the indiscriminate use of these substances generates resistance. Pyriproxyfen belongs to an insect growth disruptors class with mechanisms of action for the control of immature forms of the insect. The aim of this study was to investigate the potential of pyriproxyfen administered orally to cattle for the control of the horn fly. In vitro bioassays were carried out by evaluating the number of adults emerged from 30 eggs per replicate, in triplicate, added in a substrate (fresh cattle feces) spiked with pyriproxyfen solutions in the concentration range of 2-130 ppb (ng.g-1). Probit analysis estimated LC50 value of 7.89 ppb and LC90 value of 70.08 ppb. The doses used in the in vivo evaluation were established based on the LC90 values and the anatomical and physiological aspects of the bovine digestive tract. Capsules containing pyriproxyfen at doses of 2.5 mg (G2.5) and 40 mg (G40) were produced and administered orally by bolus applicator for 12 days. The efficacy of pyriproxyfen against the immature forms of H. irritans was determined by incubating eggs in vitro in the feces collected on days 0, +3, +6, +10 and +13. Quantification of pyriproxyfen in feces was performed by UPLC-MS/MS, finding concentrations ranging from 13.4 to 22.6 ppb for G2.5 and between 268.5 to 509.0 ppb for G40. Pyriproxyfen administered orally is eliminated in the active form in the fecal mass and at a dose of 40 mg.day-1 (0.1 mg/kg/day) generates fecal concentrations able to produce 100 % prevention of adults emergence of H. irritans.

Assuntos

RESUMO

The horn fly (Haematobia irritans) is particularly unique among the parasites that primarily affect Brazilian cattle farming. Appropriate control strategies fundamentally depend on epidemiological knowledge, which is particularly scarce in Northeastern Brazil. This study aimed to elucidate the ecology of the immature horn fly in the semiarid region of Brazil. Bovine fecal masses were collected and covered with emergence traps to collect the horn fly for sexing and counting. Weather records of the region were concurrently acquired. A total of 11,390H. irritans were collected from 601 fecal masses, with a sex ratio of 0.9:1 (male: female). Horn fly emergence was observed in 78% (15%-100%) of the fecal masses, varying from 1 to 185 (mean = 23.3) flies/fecal mass, predominantly at the beginning of the rainy season. The minimum period for egg-to-adult development of H. irritans varied from 7 to 11 days, indicating the occurrence of 30 generations per year in the region. Rapid development of the immature horn fly in the semiarid region, throughout the year may results in a high number of generations and infestations in cattle herds.

Assuntos

RESUMO

Abstract To identify susceptible and resistant Haematobia irritans cows, horn flies were counted biweekly for 3 years in a herd of 25 Sindhi cows. Repeated measures linear mixed models were created including cow as a random factor. The results were analyzed by: 1) observing horn fly counts, considering fly-susceptible cows with infestations appearing in the upper quartile more than 50% of the weeks and in the lower quartile less than 20% of the weeks, and fly-resistant cows those that the number of flies was in the lower quartile more than 50% of the weeks and in the upper quartile less than 20%; 2) by the best linear unbiased predictions (BLUPs), to evaluate the cow effect on fly counts. Fly-susceptible cows were those in which the infestation appeared in the 90th percentile of the BLUPs, whereas fly-resistant cows appeared in the 10th percentile. For the observational method the individuals identified as resistant varied between 8% and 20% and 8% to 12% were susceptible. For the BLUP method, the rates of susceptible and resistant cows were 12%. The agreement among methods suggests that susceptible cows can be identified by observations of fly counts, allowing for selective breeding, culling or treatment.

Resumo Para identificar vacas susceptíveis e resistentes à Haematobia irritans, moscas-dos-chifres foram contadas quinzenalmente durante três anos em 25 vacas de um rebanho Sindhi. Modelos lineares de medidas repetidas foram criados, analisando os resultados de duas formas: 1) pela contagem das moscas, considerando susceptíveis as vacas nas quais a infestação aparecia no quartil superior mais de 50% das semanas e no quartil inferior menos de 20% das semanas. Vacas resistentes foram consideradas aquelas nas quais o número de moscas apareceu no quartil inferior mais de 50% das semanas e no quartil superior menos de 20% das semanas; 2) pela melhor predição linear não-viesada (BLUP), para avaliar o efeito das vacas na contagem de moscas. As vacas foram consideradas susceptíveis quando apareciam no percentil 90 dos BLUPs e resistentes quando apareciam no percentil 10. O método observacional identificou 8% a 20% de indivíduos resistentes e 8% a 12% de susceptíveis. O método dos BLUPs identificou igual taxa de 12% de indivíduos susceptíveis e resistentes. A forte concordância entre estes dois métodos sugere que as vacas susceptíveis podem ser identificadas pela contagem das moscas, o que permite estabelecer seleção dos animais resistentes ou tratamento ou eliminação dos mais susceptíveis.

Assuntos

RESUMO

Bovine leukemia virus (BLV) is the agent responsible for enzootic bovine leukosis, the most common neoplastic disease in cattle. The horn fly, a major hematophagous pest of cattle, is able to transmit different diseases in cattle. However, its implication in BLV transmission under a natural environment is still discussed. The objectives of this work were to determine the presence of BLV in horn flies (by sequencing) and to evaluate the ability of horn flies to transmit BLV to cattle (through an experimental assay under a natural environment). To demonstrate the presence of BLV in the flies, 40 horn flies were collected from a BLV-positive cow with a sweep net and 10 pools with four horn-fly mouthparts each were prepared. The presence of BLV was determined by nested polymerase chain reaction and sequencing. To demonstrate BLV transmission, other 40 flies were collected from the same BLV-positive cow with a sweep net. Eight homogenates containing five horn-fly mouthparts each were prepared and injected to eight cows of different breeds, and blood samples were collected every 21 days. Then, to evaluate the ability of horn flies to transmit BLV to grazing cattle under natural conditions, both infected and uninfected cattle from the experimental transmission assay were kept together in the same paddock with more than 200 horn flies per animal for 120 days. Blood samples were collected every 20 days and the number of flies was determined. The sequencing results confirmed the presence of the provirus in horn flies. The results also confirmed that BLV transmission is a possible event, at least experimentally. However, the role of horn flies as vectors of BLV under a natural grazing system is still discussed.

Assuntos

RESUMO

ABSTRACT Objective. Assess the efficacy of Metarhizium anisopliae strain 135 (Ma135) applied by aspersion to reduce simultaneous infestation of Haematobia irritans and Stomoxys calcitrans in naturally infested cattle maintained in a production system which combine grazing and confinement in pens. Materials and methods. Was applied an aqueous formulation of Ma135 (1x108 conidia/ml) on a nine cows group in six occasions with seven days interval, while the control group received the same formulation without conidial content. The infestation index was estimated daily for each fly independently; the effectiveness of the formulation was calculated using the Abbott's formula. Results. The Ma135 formulation had a reduction in the fly population of 58% for H. irritans and 69% for S. calcitrans, taking into consideration the six study weeks, in addition to causing no negative effects on animal health. An Infestation index reduction was observed from the first week post-treatment (p<0.05) and maintained this trend throughout the study. Conclusions. The present study has demonstrated the potential of strain Ma135 to reduce the simultaneous infestation of both hematophagous flies in cattle under conditions of natural infestation.

RESUMEN Objetivo. Evaluar la eficacia de la cepa 135 de Metarhizium anisopliae (Ma135) aplicada por aspersión para reducir la infestación simultánea de Haematobia irritans y Stomoxys calcitrans en ganado naturalmente infestado mantenido en un sistema de producción de leche que combina el pastoreo y el confinamiento en corrales. Materiales y métodos. Se aplicó una formulación acuosa de Ma135 (1x108 conidios/ml) a un grupo de nueve vacas en seis ocasiones con un intervalo de siete días, mientras que el grupo control recibió una solución compuesta por agua, Monooleato de polioxietileno sorbitán en solución 0.01% y un adyuvante agrícola al 0.1%. Se estimó diariamente el índice de infestación para cada mosca de forma independiente; la efectividad de la formulación se calculó usando la fórmula de Abbott. Resultados. La formulación de Ma135 tuvo una eficacia en el control de la infestación de 58% para el caso de H. irritans y de 69% para S. calcitrans, tomando en cuenta las seis semanas de estudio, además de que no causó ningún efecto negativo en la salud de los animales. La reducción del índice de infestación se observó desde la primera semana post-tratamiento (p<0.05) y mantuvo esta tendencia durante todo el estudio. Conclusiones. El presente estudio ha demostrado el potencial de la cepa Ma135 para reducir la infestación simultánea de ambas moscas hematófagas en el ganado bajo condiciones de infestación natural.

Assuntos

RESUMO

To identify susceptible and resistant Haematobia irritans cows, horn flies were counted biweekly for 3 years in a herd of 25 Sindhi cows. Repeated measures linear mixed models were created including cow as a random factor. The results were analyzed by: 1) observing horn fly counts, considering fly-susceptible cows with infestations appearing in the upper quartile more than 50% of the weeks and in the lower quartile less than 20% of the weeks, and fly-resistant cows those that the number of flies was in the lower quartile more than 50% of the weeks and in the upper quartile less than 20%; 2) by the best linear unbiased predictions (BLUPs), to evaluate the cow effect on fly counts. Fly-susceptible cows were those in which the infestation appeared in the 90th percentile of the BLUPs, whereas fly-resistant cows appeared in the 10th percentile. For the observational method the individuals identified as resistant varied between 8% and 20% and 8% to 12% were susceptible. For the BLUP method, the rates of susceptible and resistant cows were 12%. The agreement among methods suggests that susceptible cows can be identified by observations of fly counts, allowing for selective breeding, culling or treatment.(AU)

Para identificar vacas susceptíveis e resistentes à Haematobia irritans, moscas-dos-chifres foram contadas quinzenalmente durante três anos em 25 vacas de um rebanho Sindhi. Modelos lineares de medidas repetidas foram criados, analisando os resultados de duas formas: 1) pela contagem das moscas, considerando susceptíveis as vacas nas quais a infestação aparecia no quartil superior mais de 50% das semanas e no quartil inferior menos de 20% das semanas. Vacas resistentes foram consideradas aquelas nas quais o número de moscas apareceu no quartil inferior mais de 50% das semanas e no quartil superior menos de 20% das semanas; 2) pela melhor predição linear não-viesada (BLUP), para avaliar o efeito das vacas na contagem de moscas. As vacas foram consideradas susceptíveis quando apareciam no percentil 90 dos BLUPs e resistentes quando apareciam no percentil 10. O método observacional identificou 8% a 20% de indivíduos resistentes e 8% a 12% de susceptíveis. O método dos BLUPs identificou igual taxa de 12% de indivíduos susceptíveis e resistentes. A forte concordância entre estes dois métodos sugere que as vacas susceptíveis podem ser identificadas pela contagem das moscas, o que permite estabelecer seleção dos animais resistentes ou tratamento ou eliminação dos mais susceptíveis.(AU)

Assuntos

RESUMO

The use of silvopastoral systems (SPS) can be a good alternative to reduce the environmental impacts of livestock breeding in Brazil. One of the reasons for its scarce adoption is the lack of information on health and productivity of cattle raised under these conditions. The experiment reported here was designed to compare the infestation by external parasites - the cattle tick (Rhipicephalus microplus), horn fly (Haematobia irritans), and larvae of the botfly (Dermatobia hominis) - in beef cattle raised in a SPS and a conventional pasture system (CPS), evaluated for 24 months. Data on air and soil temperature, solar radiation, wind incidence and water balance were used to characterize the SPS and CPS. R. microplus adult females and D. hominis larvae were counted on the body of each animal to determine the parasites burdens, but we did not find significant differences between the two systems. Horn flies counts on animals' body, and analysis of the horn fly and its pupal parasitoids associated with the dung pats were obtained in the two systems. Horn fly infestation was significantly lower (p=0.01) in the SPS (13.17±3.46) in comparison with the CPS (24.02±4.43). In SPS and CPS, respectively, the mean densities of pupae of H. irritansin dung pats were 9.8 and 10.7; the mean density of adults of H. irritans, 3.7 and 3.5; and the density of its pupal parasitoids were 20.5 and 5.4. The effect of production system was significant (p<0.05) only for the occurrence of pupal parasitoids of the horn fly, where the greatest occurrences of these natural enemies were in the SPS. These data indicate that natural enemies were able to control, at least partially, the horn fly populations in the cattle.

Assuntos

RESUMO

En Andradina, estado de São Paulo, el grado de resistencia contra endo y ectoparásitos se evaluó en tres grupos genéticos de novillas: Aberdeen Angus x Neloré (Nel x AAN; n = 12), Guzerá (Guz; n = 22) y Neloré (Nel, n = 24). Durante 12 meses, el peso corporal de cada animal fue medido cada 28 días, se realizó conteo del número de moscas Haematobia irritans sobre los animales y se tomaron muestras fecales para realizar el conteo de huevos de nematodos por gramo de heces (OPG). El grupo de novillas Nel X AAN presentó recuentos más altos de moscas en comparación con otros grupos durante el experimento. Se encontró relación significativa (P < 0,001) entre el número de moscas y el tiempo, aumentando dicha diferencia entre los grupos con el tiempo. El grupo Nel presento conteos más bajos de OPG en cuatro de los doce meses de experimentación. Los animales del grupo Nel x AAN tuvieron una ganancia de peso corporal mayor al promedio desde el comienzo del experimento. Se presentó una relación significativa entre la ganancia de peso y el tiempo (P < 0,001) y la diferencia de peso del grupo Nel x AAn aumentó a lo largo del tiempo en relación con los grupos de Guz y Nel. Se puede concluir que las hembras mestizas Nel x AAN mostraron un aumento de peso mayor en comparación con los grupos de Guz y Nel, aunque estas fueron más afectadas por Haematobia irritans. En conclusión, el uso de animales mestizos es unabuena estrategia para aumentar la eficiencia en la producción de carne.(AU)

In Andradina, São Paulo state, the degree of resistance against endo- and ectoparasites was evaluated in heifers from three genetic groups: crossbred Nellore x Aberdeen Angus (Nel x AAn; n=12), Guzerá (Guz; n=22) and Nellore (Nel; n=24). During 12 months, the body weight of each animal was recorded every 28 days as well as the number of Haematobia irritans flies near the animals, and fecal samples were collected to count nematode eggs per gram of feces (EPG). The Nel x AAn group had higher fly counts in comparison with other groups throughout the experiment. There was a significant interaction (P <0.001) between the number of flies and time, and the difference between groups increased over time. The Nel group had lower mean EPG values in four of the twelve experimental months. The animals of the Nel x AAn group had higher average body weight gain since the beginning of the experiment. There was a significant interaction between weight gain and time (P < 0.001) and the difference in weight of the Nel x AAn group increased over time in relation to the Guz and Nel groups. It can be concluded that the crossbred Nel x AAn females presented superior weight gain in relation to the Guz and Nel groups, although they were more affected by Haematobia irritans. In conclusion, the use of crossbred cattle is a good strategy to increase the efficiency of meat production.(AU)

Em Andradina, estado de São Paulo, o grau de resistência contra endo e ectoparasitas foi avaliado em novilhas de três grupos genéticos: mestiços Nelore x Aberdeen Angus (Nel x AAn; n=12), Guzerá (Guz; n = 22) e Nelore (Nel; n = 24). Durante 12 meses, o peso corporal de cada animal foi aferido a cada 28 dias, bem como a contagem do número de moscas Haematobia irritans nos animais, e amostras fecais foram colhidas para contagem de ovos de nemátodeos por grama de fezes (OPG). O grupo Nel x AAn apresentaram maiores contagens de moscas, em comparação com outros grupos, durante o experimento. Houve interação significativa (P < 0,001) entre o número de moscas e o tempo, sendo que a diferença entre os grupos aumentou ao longo do tempo. O grupo Nel apresentou menores contagens médias de OPG em quatro dos doze meses experimentais. Os animais do grupo Nel x AAn apresentaram maior ganho de peso corporal médio desde o início do experimento. Houve interação significativa entre o ganho de peso e tempo (P < 0,001) e a diferença de peso do grupo Nel x AAn aumentou ao longo do tempo, em relação aos grupos Guz e Nel. Pode-se concluir que fêmeas mestiças Nel x AAN apresentaram ganho de peso superior em relação aos grupos Guz e Nel, embora elas fossem mais afetadas por Haematobia irritans. Em conclusão, a utilização de bovinos mestiços é uma boa estratégia para aumentar a eficiência da produçãode carne.(AU)

Assuntos

RESUMO

En Andradina, estado de São Paulo, el grado de resistencia contra endo y ectoparásitos se evaluó en tres grupos genéticos de novillas: Aberdeen Angus x Neloré (Nel x AAN; n = 12), Guzerá (Guz; n = 22) y Neloré (Nel, n = 24). Durante 12 meses, el peso corporal de cada animal fue medido cada 28 días, se realizó conteo del número de moscas Haematobia irritans sobre los animales y se tomaron muestras fecales para realizar el conteo de huevos de nematodos por gramo de heces (OPG). El grupo de novillas Nel X AAN presentó recuentos más altos de moscas en comparación con otros grupos durante el experimento. Se encontró relación significativa (P < 0,001) entre el número de moscas y el tiempo, aumentando dicha diferencia entre los grupos con el tiempo. El grupo Nel presento conteos más bajos de OPG en cuatro de los doce meses de experimentación. Los animales del grupo Nel x AAN tuvieron una ganancia de peso corporal mayor al promedio desde el comienzo del experimento. Se presentó una relación significativa entre la ganancia de peso y el tiempo (P < 0,001) y la diferencia de peso del grupo Nel x AAn aumentó a lo largo del tiempo en relación con los grupos de Guz y Nel. Se puede concluir que las hembras mestizas Nel x AAN mostraron un aumento de peso mayor en comparación con los grupos de Guz y Nel, aunque estas fueron más afectadas por Haematobia irritans. En conclusión, el uso de animales mestizos es unabuena estrategia para aumentar la eficiencia en la producción de carne.

In Andradina, São Paulo state, the degree of resistance against endo- and ectoparasites was evaluated in heifers from three genetic groups: crossbred Nellore x Aberdeen Angus (Nel x AAn; n=12), Guzerá (Guz; n=22) and Nellore (Nel; n=24). During 12 months, the body weight of each animal was recorded every 28 days as well as the number of Haematobia irritans flies near the animals, and fecal samples were collected to count nematode eggs per gram of feces (EPG). The Nel x AAn group had higher fly counts in comparison with other groups throughout the experiment. There was a significant interaction (P <0.001) between the number of flies and time, and the difference between groups increased over time. The Nel group had lower mean EPG values in four of the twelve experimental months. The animals of the Nel x AAn group had higher average body weight gain since the beginning of the experiment. There was a significant interaction between weight gain and time (P < 0.001) and the difference in weight of the Nel x AAn group increased over time in relation to the Guz and Nel groups. It can be concluded that the crossbred Nel x AAn females presented superior weight gain in relation to the Guz and Nel groups, although they were more affected by Haematobia irritans. In conclusion, the use of crossbred cattle is a good strategy to increase the efficiency of meat production.

Em Andradina, estado de São Paulo, o grau de resistência contra endo e ectoparasitas foi avaliado em novilhas de três grupos genéticos: mestiços Nelore x Aberdeen Angus (Nel x AAn; n=12), Guzerá (Guz; n = 22) e Nelore (Nel; n = 24). Durante 12 meses, o peso corporal de cada animal foi aferido a cada 28 dias, bem como a contagem do número de moscas Haematobia irritans nos animais, e amostras fecais foram colhidas para contagem de ovos de nemátodeos por grama de fezes (OPG). O grupo Nel x AAn apresentaram maiores contagens de moscas, em comparação com outros grupos, durante o experimento. Houve interação significativa (P < 0,001) entre o número de moscas e o tempo, sendo que a diferença entre os grupos aumentou ao longo do tempo. O grupo Nel apresentou menores contagens médias de OPG em quatro dos doze meses experimentais. Os animais do grupo Nel x AAn apresentaram maior ganho de peso corporal médio desde o início do experimento. Houve interação significativa entre o ganho de peso e tempo (P < 0,001) e a diferença de peso do grupo Nel x AAn aumentou ao longo do tempo, em relação aos grupos Guz e Nel. Pode-se concluir que fêmeas mestiças Nel x AAN apresentaram ganho de peso superior em relação aos grupos Guz e Nel, embora elas fossem mais afetadas por Haematobia irritans. Em conclusão, a utilização de bovinos mestiços é uma boa estratégia para aumentar a eficiência da produçãode carne.

Assuntos

RESUMO

The purpose of this paper is to evaluate the effect of five strains of Metarhizium anisopliae (Ma) and three strains of Isaria fumosorosea (Ifr) at a concentration of 1×10(8)colony-forming units/ml applied by spraying onto bovines with controlled infestation of Haematobia irritans under stable conditions in the Mexican dry tropics. Four experiments were performed, in each of which three treatments (two fungal strains and one control) were evaluated with eight repetitions for each one, by carrying out a single application of the aqueous suspension of each strain. The animals were isolated in individual cages and direct counts of the infestation were carried out for 13 days. It was observed that strains Ma2, Ma6, Ma10, Ma14, and Ma34 caused 94-100% reduction in infestation between days 12 and 13 post-treatment, while strains Ifr19, Ifr11, and Ifr12 reduced infestation from 90% to 98% up to day 13 post-application. There was an effect in the generation of horn flies from the excrement of bovines that were treated with different strains, reducing the reproduction of subsequent generations. It was concluded that the strains of M. anisopliae and I. fumosorosea evaluated in this study can be used as biocontrol agents in infestations of H. irritans in stabled bovines.

Assuntos

RESUMO

The aim of this study was to evaluate the efficacy of herbal, homeopathic and allopathic treatments for parasites in beef heifers during two experimental cycles of 318 and 313 days. Treatments: NC - negative control (untreated); HH - treated with homeopathic preparation Homeo bovis Parasitário®; PC - (positive control) - treated with 10% moxidectina® and an acaricide formulation of cypermethrin, chlorpyrifos and piperonyl butoxide®; HF ­ treated with homeopathic preparation Fator C&MC®; and FN - treated with neem cake (torta de neem®) and with neem oil (óleo de neem®). Parasite egg count (EPG), horn fly (Haematobia irritans) and tick (Rhipicephalus (Boophilus) microplus) assessment and animal weighting were performed at 28-day intervals. Blood samples were collected at the first cycle to assess the immune response. Horn fly infestation was not affected by any treatment (P>0.05). The mean number of ticks, which was low in both cycles, was lower (P<0.05) in the first cycle in animals that received PC treatment. In both experimental cycles, the mean EPG of the PC-treated animals was lower (P<0.05) than the animals receiving other treatments. Treatments had no effect on the immune response (P>0.05). The animals treated with allopathic drugs were 22 to 30 kg heavier (P<0.05) than untreated animals or animals treated with alternative drugs.

O objetivo do trabalho foi avaliar a eficácia de tratamentos fitoterápicos, homeopáticos e alopáticos contra ecto e endoparasitas na recria de novilhas, em dois ciclos experimentais subsequentes de 318 e 313 dias. Tratamentos: CN - controle negativo - não tratado; tratamento HH - tratado com homeopático Homeo bovis Parasitário®; tratamento CP ­ controle positivo ­ tratado com moxidectina 10%® e uma formulação acaricida contendo cypermetrina, clorpirifós e butóxido de piperonila®; tratamento HF - tratado com homeopático Fator C&MC® e tratamento FN - tratados com torta de neem® e com óleo de neem®. A contagem de ovos nas fezes (OPG), a infestação por Haematobia irritans, Rhipicephalus (Boophilus) microplus e pesagem dos animais foram realizadas em intervalos de 28 dias. No primeiro ciclo foi coletado sangue para avaliar a resposta imume. A infestação por mosca-dos-chifres não foi influenciada por nenhum dos tratamentos (P>0,05). Nos dois ciclos o número médio de carrapatos foi baixo e apenas no primeiro foi menor (P>0.05) no tratamento CP em relação aos demais. A média de OPG no tratamento CP foi mais baixa que nos demais tratamentos nos dois ciclos experimentais (P<0,05). Não houve efeito de tratamentos na resposta imune. Os animais do tratamento CP ganharam entre 22 a 30 kg de peso vivo a mais (P<0,05) que os não tratados ou tratados com medicamentos alternativos.

Assuntos

RESUMO

Background: The horn fly, Haematobia irritans, is an obligate bloodsucking ectoparasite of pastured cattle and is a major pest of livestock production in North and South America and Europe. In this study, we investigated the potential to use cattle pastures, infected with non-toxic, "friendly" fungal-endophyte-infected (E+) tall fescue, Festuca arundinacea Schreb., as a strategy for reducing horn fly loads in cattle, and to evaluate the possible bioinsecticide effect on horn fly larvae. Results: When cattle grazed in E+ tall fescue, a decrease in fly-load was observed, compared with other pastures (endophyte-free (E-) pastures). The infestation of horn fly load decreased according to an increase in the percentage of endophyte present in the different pastures (0 to 100%). Moreover, two groups of animals with significant differences in the fly-load (high and low fly-load) in the same herd were observed (P < 0.05). Additionally, it was possible to determine a bioinsecticide effect of cattle dung, upon horn fly larvae (80%), from animals fed E+ tall fescue. Conclusions: These results constitute the first report on the potential for exploiting pasture management for controlling 1) horn fly-loads on cattle and 2) the normal development of horn fly larvae. In conclusion, this information provides preliminary understanding of the role of cattle pasture diet management for controlling horn fliesas part of an integrated pest management strategy for this major pest of farmed livestock.

Assuntos

RESUMO

Horn fly resistance to pyrethroid insecticides occurs throughout Brazil, but knowledge about the involved mechanisms is still in an incipient stage. This survey was aimed to identify the mechanisms of horn fly resistance to cypermethrin in Mato Grosso do Sul state, Brazil. Impregnated filter paper bioassays using cypermethrin, synergized or not with piperonyl butoxide (PBO) and triphenyl phosphate (TPP), were conducted from March 2004 to June 2005 in horn fly populations (n = 33) from all over the state. All populations were highly resistant to cypermethrin, with resistance factors (RF) ranging from 89.4 to 1,020.6. Polymerase chain reaction (PCR) assays to detect the knockdown resistance (kdr) mutation also were performed in 16 samples. The kdr mutation was found in 75% of the tested populations, mostly with relatively low frequencies (<20%), and was absent in some highly resistant populations. Addition of TPP did not significantly reduce the LC50 in any population. However, PBO reduced LC50s above 40-fold in all tested populations, resulting in RFs ≤ 10 in most cases. Horn fly resistance to cypermethrin is widespread in the state, being primarily caused by an enhanced activity of P450 mono-oxygenases and secondarily by reduced target site sensitivity.

Resistência da mosca-dos-chifres a inseticidas piretróides ocorre em todo o país, entretanto, o conhecimento sobre os mecanismos envolvidos é ainda incipiente. Este estudo objetivou identificar os mecanismos de resistência desta mosca à cipermetrina em Mato Grosso do Sul. Bioensaios utilizando papéis impregnados com cipermetrina, isoladamente ou sinergizada por butóxido de piperonila (PBO) ou trifenil fosfato (TPP), foram realizados de março∕2004 a junho∕2005 em 33 populações. Todas as populações apresentaram elevada resistência à cipermetrina, com fatores de resistência (FR) variando de 89,4 a 1.020,6. Ensaios de reação em cadeia da polimerase (PCR) visando a detecção de kdr ("knockdown resistance") foram realizados em 16 amostras. A mutação kdr foi detectada em 75% das populações, geralmente em baixas frequências (<20%) e ausente em algumas populações resistentes. A adição de TPP não reduziu significativamente a CL50 em nenhuma população. Entretanto, o PBO reduziu em mais de 40 vezes a CL50 de todas as populações testadas, resultando em FR ≤ 10 na maioria dos casos. Resistência da mosca-dos-chifres à cipermetrina encontra-se disseminada no estado, sendo causada primariamente por um aumento da atividade de P450 mono-oxigenases e secundariamente pela redução da sensibilidade do sítio de ação do inseticida.

Assuntos

RESUMO

The aim of this study was to evaluate the efficacy of herbal, homeopathic and allopathic treatments for parasites in beef heifers during two experimental cycles of 318 and 313 days. Treatments: NC - negative control (untreated); HH - treated with homeopathic preparation Homeo bovis Parasitário®; PC - (positive control) - treated with 10% moxidectina® and an acaricide formulation of cypermethrin, chlorpyrifos and piperonyl butoxide®; HF treated with homeopathic preparation Fator C&MC®; and FN - treated with neem cake (torta de neem®) and with neem oil (óleo de neem®). Parasite egg count (EPG), horn fly (Haematobia irritans) and tick (Rhipicephalus (Boophilus) microplus) assessment and animal weighting were performed at 28-day intervals. Blood samples were collected at the first cycle to assess the immune response. Horn fly infestation was not affected by any treatment (P>0.05). The mean number of ticks, which was low in both cycles, was lower (P 0.05) in the first cycle in animals that received PC treatment. In both experimental cycles, the mean EPG of the PC-treated animals was lower (P 0.05) than the animals receiving other treatments. Treatments had no effect on the immune response (P>0.05). The animals treated with allopathic drugs were 22 to 30 kg heavier (P 0.05) than untreated animals or animals treated with alternative drugs.

O objetivo do trabalho foi avaliar a eficácia de tratamentos fitoterápicos, homeopáticos e alopáticos contra ecto e endoparasitas na recria de novilhas, em dois ciclos experimentais subsequentes de 318 e 313 dias. Tratamentos: CN - controle negativo - não tratado; tratamento HH - tratado com homeopático Homeo bovis Parasitário®; tratamento CP controle positivo tratado com moxidectina 10%® e uma formulação acaricida contendo cypermetrina, clorpirifós e butóxido de piperonila®; tratamento HF - tratado com homeopático Fator C&MC® e tratamento FN - tratados com torta de neem® e com óleo de neem®. A contagem de ovos nas fezes (OPG), a infestação por Haematobia irritans, Rhipicephalus (Boophilus) microplus e pesagem dos animais foram realizadas em intervalos de 28 dias. No primeiro ciclo foi coletado sangue para avaliar a resposta imume. A infestação por mosca-dos-chifres não foi influenciada por nenhum dos tratamentos (P>0,05). Nos dois ciclos o número médio de carrapatos foi baixo e apenas no primeiro foi menor (P>0.05) no tratamento CP em relação aos demais. A média de OPG no tratamento CP foi mais baixa que nos demais tratamentos nos dois ciclos experimentais (P 0,05). Não houve efeito de tratamentos na resposta imune. Os animais do tratamento CP ganharam entre 22 a 30 kg de peso vivo a mais (P 0,05) que os não tratados ou tratados com medicamentos alternativos.

RESUMO

Horn fly resistance to pyrethroid insecticides occurs throughout Brazil, but knowledge about the involved mechanisms is still in an incipient stage. This survey was aimed to identify the mechanisms of horn fly resistance to cypermethrin in Mato Grosso do Sul state, Brazil. Impregnated filter paper bioassays using cypermethrin, synergized or not with piperonyl butoxide (PBO) and triphenyl phosphate (TPP), were conducted from March 2004 to June 2005 in horn fly populations (n = 33) from all over the state. All populations were highly resistant to cypermethrin, with resistance factors (RF) ranging from 89.4 to 1,020.6. Polymerase chain reaction (PCR) assays to detect the knockdown resistance (kdr) mutation also were performed in 16 samples. The kdr mutation was found in 75% of the tested populations, mostly with relatively low frequencies ( 20%), and was absent in some highly resistant populations. Addition of TPP did not significantly reduce the LC50 in any population. However, PBO reduced LC50s above 40-fold in all tested populations, resulting in RFs 10 in most cases. Horn fly resistance to cypermethrin is widespread in the state, being primarily caused by an enhanced activity of P450 mono-oxygenases and secondarily by reduced target site sensitivity.

Resistência da mosca-dos-chifres a inseticidas piretróides ocorre em todo o país, entretanto, o conhecimento sobre os mecanismos envolvidos é ainda incipiente. Este estudo objetivou identificar os mecanismos de resistência desta mosca à cipermetrina em Mato Grosso do Sul. Bioensaios utilizando papéis impregnados com cipermetrina, isoladamente ou sinergizada por butóxido de piperonila (PBO) ou trifenil fosfato (TPP), foram realizados de março2004 a junho2005 em 33 populações. Todas as populações apresentaram elevada resistência à cipermetrina, com fatores de resistência (FR) variando de 89,4 a 1.020,6. Ensaios de reação em cadeia da polimerase (PCR) visando a detecção de kdr(knockdown resistance) foram realizados em 16 amostras. A mutação kdr foi detectada em 75% das populações, geralmente em baixas frequências ( 20%) e ausente em algumas populações resistentes. A adição de TPP não reduziu significativamente a CL50 em nenhuma população. Entretanto, o PBO reduziu em mais de 40 vezes a CL50 de todas as populações testadas, resultando em FR 10 na maioria dos casos. Resistência da mosca-dos-chifres à cipermetrina encontra-se disseminada no estado, sendo causada primariamente por um aumento da atividade de P450 mono-oxigenases e secundariamente pela redução da sensibilidade do sítio de ação do inseticida.

RESUMO

O controle eficaz de Haematobia irritans (mosca-dos-chifres) e Rhipicephalus (Boophilus) microplus (carrapato-do-boi) é um fator crucial à maior rentabilidade da pecuária brasileira, porém ainda constitui-se um desafio. Um maior conhecimento das práticas adotadas no combate destes parasitos faz-se necessário para que se possam estruturar estratégias de controle mais próximas da realidade do produtor rural e mais fáceis de serem executadas. Este estudo caracterizou, através de entrevistas, as práticas adotadas no controle desses ectoparasitos em 23 propriedades da mesorregião do Triângulo Mineiro e Alto Paranaíba, Minas Gerais. A maioria dos entrevistados reconheceu a importância desses parasitos para a atividade pecuária, entretanto, diversos problemas relativos ao controle parasitário foram observados. O controle da mosca-dos-chifres e do carrapato-do-boi era uma prática rotineira em, respectivamente, 17,4% e 95,7% das propriedades, geralmente realizado em função de elevado grau de infestação dos animais. Mais de seis aplicações de ectoparasiticidas eram realizadas por ano em todas as propriedades que empregavam tratamentos para o controle da mosca e em 76,5% daquelas que combatiam o carrapato. Os produtos eram aplicados principalmente com bombas costais manuais (63,6%) e sem a contenção dos animais em 45,5% das propriedades. A diluição dos produtos segundo recomendações dos fabricantes era realizada por 45,4% dos entrevistados, porém, 63,6% aplicavam um volume de solução por animal menor do que o tecnicamente recomendado. Utilizava-se principalmente a associação de piretróides e organofosforados para o controle de ambos os parasitos. Apesar de utilizar rotineiramente ectoparasiticidas, o uso de equipamento de proteção individual (EPI) não era comum entre os entrevistados. A maioria dos entrevistados conhecia algumas características epidemiológicas dos parasitos, entretanto, o controle parasitário adotado na maior parte das propriedades tende a comprometer não apenas a eficácia dos tratamentos, mas a suscetibilidade dos parasitos e a sustentabilidade do controle.(AU)

The effective control of Haematobia irritans (horn fly) and Rhipicephalus (Boophilus) microplus (cattle tick) is crucial for increasing the productivity of livestock industry in Brazil, but still remains a challenge. A greater knowledge about parasite control in the field is necessary to establish control strategies closer to farmer's reality and easier to be performed. This study characterized the practices adopted for controlling such ectoparasites on 23 cattle ranches from the Triângulo Mineiro and Alto Paranaíba region in the state of Minas Gerais, through interviews. Most interviewees recognized the importance of these parasites to livestock, however, many problems related to parasite control were observed. Control of horn flies and cattle tick was a routine in 17.4% and 95.7% of the ranches, respectively, triggered by high infestations on animals. More than six insecticide/acaricide treatments were applied yearly in all cattle ranches controlling horn flies and in 76.5% of the ranches controlling the cattle tick. Pesticide products were applied mostly by manual backpack sprayers (63.6%) without restraining the animals in 45.5% of ranches. Product dilution following manufacturer's recommendations was performed by 45.5% of interviewees, but 63.6% of them used lower doses per animal than technically recommended. Associations of organophosphates and pyrethroids were the main products used to control both parasites. Although pesticide use was a routine practice, the use of personal protective equipment (PPE) was not common among surveyed people. Most interviewees were able to recognize epidemiological characteristics of the parasites; however, parasite control measures adopted at most cattle ranches tend to jeopardize the efficacy of products, susceptibility of parasites and sustainability of control programs.(AU)

Assuntos

RESUMO

O controle eficaz de Haematobia irritans (mosca-dos-chifres) e Rhipicephalus (Boophilus) microplus (carrapato-do-boi) é um fator crucial à maior rentabilidade da pecuária brasileira, porém ainda constitui-se um desafio. Um maior conhecimento das práticas adotadas no combate destes parasitos faz-se necessário para que se possam estruturar estratégias de controle mais próximas da realidade do produtor rural e mais fáceis de serem executadas. Este estudo caracterizou, através de entrevistas, as práticas adotadas no controle desses ectoparasitos em 23 propriedades da mesorregião do Triângulo Mineiro e Alto Paranaíba, Minas Gerais. A maioria dos entrevistados reconheceu a importância desses parasitos para a atividade pecuária, entretanto, diversos problemas relativos ao controle parasitário foram observados. O controle da mosca-dos-chifres e do carrapato-do-boi era uma prática rotineira em, respectivamente, 17,4% e 95,7% das propriedades, geralmente realizado em função de elevado grau de infestação dos animais. Mais de seis aplicações de ectoparasiticidas eram realizadas por ano em todas as propriedades que empregavam tratamentos para o controle da mosca e em 76,5% daquelas que combatiam o carrapato. Os produtos eram aplicados principalmente com bombas costais manuais (63,6%) e sem a contenção dos animais em 45,5% das propriedades. A diluição dos produtos segundo recomendações dos fabricantes era realizada por 45,4% dos entrevistados, porém, 63,6% aplicavam um volume de solução por animal menor do que o tecnicamente recomendado. Utilizava-se principalmente a associação de piretróides e organofosforados para o controle de ambos os parasitos. Apesar de utilizar rotineiramente ectoparasiticidas, o uso de equipamento de proteção individual (EPI) não era comum entre os entrevistados. A maioria dos entrevistados conhecia algumas características epidemiológicas dos parasitos, entretanto, o controle parasitário adotado na maior parte das propriedades tende a comprometer não apenas a eficácia dos tratamentos, mas a suscetibilidade dos parasitos e a sustentabilidade do controle.

The effective control of Haematobia irritans (horn fly) and Rhipicephalus (Boophilus) microplus (cattle tick) is crucial for increasing the productivity of livestock industry in Brazil, but still remains a challenge. A greater knowledge about parasite control in the field is necessary to establish control strategies closer to farmer's reality and easier to be performed. This study characterized the practices adopted for controlling such ectoparasites on 23 cattle ranches from the Triângulo Mineiro and Alto Paranaíba region in the state of Minas Gerais, through interviews. Most interviewees recognized the importance of these parasites to livestock, however, many problems related to parasite control were observed. Control of horn flies and cattle tick was a routine in 17.4% and 95.7% of the ranches, respectively, triggered by high infestations on animals. More than six insecticide/acaricide treatments were applied yearly in all cattle ranches controlling horn flies and in 76.5% of the ranches controlling the cattle tick. Pesticide products were applied mostly by manual backpack sprayers (63.6%) without restraining the animals in 45.5% of ranches. Product dilution following manufacturer's recommendations was performed by 45.5% of interviewees, but 63.6% of them used lower doses per animal than technically recommended. Associations of organophosphates and pyrethroids were the main products used to control both parasites. Although pesticide use was a routine practice, the use of personal protective equipment (PPE) was not common among surveyed people. Most interviewees were able to recognize epidemiological characteristics of the parasites; however, parasite control measures adopted at most cattle ranches tend to jeopardize the efficacy of products, susceptibility of parasites and sustainability of control programs.

Assuntos

RESUMO

Much attention has been given to the development of botanical insecticides to provide effective natural control of cattle ectoparasites without harming animals, consumers, and environment. This study evaluated the efficacy of a commercial neem cake in controlling Haematobia irritans infestation on cattle. The study was conducted at the Embrapa Southeast Cattle Research Center (CPPSE), in São Carlos, SP, Brazil, from April to July 2008. The neem cake mixed in mineral salt in a 2 percent concentration was provided to 20 Nelore cows during nine weeks and had its efficacy evaluated by comparison of the infestation level against a control group. Fly infestations were recorded weekly by digital photographs of each animal from both groups and the number of flies was later counted in a computer-assisted image analyzer. Quantification of neem cake components by high-performance liquid chromatography revealed the presence of azadirachtin (421 mg.kg-1) and 3-tigloyl-azadirachtol (151 mg.kg-1) in the tested neem cake. Addition of the 2 percent neem cake reduced mineral salt intake in about 22 percent. The 2 percent neem cake treatment failed to reduce horn fly infestations on cattle during the 9-week study period.

Muita atenção tem sido dada ao desenvolvimento de inseticidas vegetais buscando-se um efetivo controle de ectoparasitas de bovinos, sem prejudicar animais, consumidores e meio ambiente. Este estudo, realizado de abril a julho de 2008, na Embrapa Pecuária Sudeste, em São Carlos, SP, Brasil, avaliou a eficácia de uma torta comercial de nim (Azadirachta indica) no controle da mosca-dos-chifres (Haematobia irritans) em bovinos. A torta de nim, misturada ao sal mineral na concentração de 2 por cento, foi fornecida a 20 vacas Nelore, durante nove semanas, e sua eficácia foi monitorada através de contagens semanais nos grupos tratado e controle. Infestações individuais foram registradas por meio de fotos digitais em todos os animais de ambos os grupos, e o número de moscas foi, posteriormente, quantificado com o auxílio de um sistema de análise de imagem computadorizado. A quantificação dos componentes da torta de nim, por cromatografia líquida, revelou a presença de azadiractina (421 mg.kg-1) e 3-tigloyl-azadirachtol (151 mg.kg-1). A adição da torta de nim a 2 por cento reduziu o consumo de sal mineral em cerca de 22 por cento. O tratamento com torta de nim a 2 por cento não reduziu as infestações por mosca-dos-chifres em bovinos durante as nove semanas do estudo.

Assuntos

RESUMO

Aiming to know the population dynamics of horn fly on cattle in the municipality of Selvíria, MS, Brazil, a study was conducted from March 2004 to June 2005 in the Education, Research and Extension Farm, from Unesp Campus de Ilha Solteira, located in the municipality of Selvíria, MS. It was used 15 cows of the Guzera breed and 15 crossbred (Guzera X Holstein-Friesian), respectively 3 and 4 years old, naturally infested. During the experimental period these animals did not receive any insecticide treatment. Visual fly counting by on back region of the animals was carried out at 14 day interval. The horn fly showed two peaks of infestation during the year, one in April and another in October. In the months of highest infestation, the average number of flies did not exceed a 104. The months in which was significant difference between crossbred and Guzera breed was in April, May, August and September 2004 and February, March and April 2005, always with crossbred with higher infestation. In the region studied Haematobia irritans was present throughout the year.

Objetivando conhecer a dinâmica populacional da mosca-dos-chifres em bovinos no município de Selvíria, MS, foi conduzido um experimento no período de março de 2004 a junho de 2005 na Fazenda de Ensino, Pesquisa e Extensão (FEPE), Unesp - Campus de Ilha Solteira, localizada no município de Selvíria, MS. Foram utilizadas 15 vacas da raça Guzerá e 15 mestiças (Guzerá x Holandesa), de 3 a 4 anos, naturalmente infestadas. Durante o período experimental estes animais não receberam tratamento inseticida e a cada 14 dias foi realizada a contagem visual de moscas sobre a região cervico-dorso-lombar. Os resultados obtidos permitiram verificar que a mosca-dos-chifres apresentou dois picos de infestação durante o ano, um no mês de abril e o outro no mês de outubro. Nos meses de maior infestação, o número médio de moscas não ultrapassou a 104. Na comparação entre as raças, os meses em que houve diferença significativa foram abril, maio, agosto e setembro de 2004, e fevereiro, março e abril de 2005, com a raça mestiça sempre apresentando maior infestação. Na região estudada Haematobia irritans estava presente durante todo o ano.

Assuntos

RESUMO

Aiming to know the population dynamics of horn fly on cattle in the municipality of Selvíria, MS, Brazil, a study was conducted from March 2004 to June 2005 in the Education, Research and Extension Farm, from Unesp Campus de Ilha Solteira, located in the municipality of Selvíria, MS. It was used 15 cows of the Guzera breed and 15 crossbred (Guzera X Holstein-Friesian), respectively 3 and 4 years old, naturally infested. During the experimental period these animals did not receive any insecticide treatment. Visual fly counting by on back region of the animals was carried out at 14 day interval. The horn fly showed two peaks of infestation during the year, one in April and another in October. In the months of highest infestation, the average number of flies did not exceed a 104. The months in which was significant difference between crossbred and Guzera breed was in April, May, August and September 2004 and February, March and April 2005, always with crossbred with higher infestation. In the region studied Haematobia irritans was present throughout the year.

Objetivando conhecer a dinâmica populacional da mosca-dos-chifres em bovinos no município de Selvíria, MS, foi conduzido um experimento no período de março de 2004 a junho de 2005 na Fazenda de Ensino, Pesquisa e Extensão (FEPE), Unesp - Campus de Ilha Solteira, localizada no município de Selvíria, MS. Foram utilizadas 15 vacas da raça Guzerá e 15 mestiças (Guzerá x Holandesa), de 3 a 4 anos, naturalmente infestadas. Durante o período experimental estes animais não receberam tratamento inseticida e a cada 14 dias foi realizada a contagem visual de moscas sobre a região cervico-dorso-lombar. Os resultados obtidos permitiram verificar que a mosca-dos-chifres apresentou dois picos de infestação durante o ano, um no mês de abril e o outro no mês de outubro. Nos meses de maior infestação, o número médio de moscas não ultrapassou a 104. Na comparação entre as raças, os meses em que houve diferença significativa foram abril, maio, agosto e setembro de 2004, e fevereiro, março e abril de 2005, com a raça mestiça sempre apresentando maior infestação. Na região estudada Haematobia irritans estava presente durante todo o ano.