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The horn fly Haematobia irritans is a cosmopolitan hematophagous ectoparasite of great importance in livestock. In Mexico, H. irritans is distributed across the country, and is found during the whole year. The fluctuation of H. irritans population is related with climate conditions. Despite its wide distribution, the effects on animal health, and its negative impact on meat and milk production, little data exists on its infestation and epidemiology is limited. This paper is a review on the current situation of H. irritans in cattle in Mexico, its economic impact, control methods, perspectives, and research opportunities. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the efficacy of the entomopathogenic fungus, Metarhizium anisopliae strain 134 (Ma134), for dairy cattle naturally infested with Haematobia irritans (L.) An aqueous formulation of 1 x 108 conidia/ml was applied by aspersion on a group of eight cows every seven days for a total of four applications, while a control group was sprayed with the same solution without conidial content. The degree of horn fly infestation was estimated daily in both groups by the direct count of adult flies found resting or feeding on the animals, and Abbott's formula was used to calculate the effectiveness of the formulation. The Ma134 formulation resulted in a 68.6 % reduction of the fly infestation during the study period, and a significant reduction was observed from the first week post-application (p < 0.05). The results show that the Ma134 formulation is effective in reducing infestations of horn fly, H. irritans, on dairy cattle under natural conditions. Thus, the fungus, Ma134, can be considered a candidate for biological control for the integrated management of H. irritans. [ABSTRACT FROM AUTHOR]

The objective of the work was to study H. irritans population fluctuation in a cattle herd in Tecoman, Colima, Mexico. The cattle herd was visited weekly from March 2003 to May 2004; on each occasion, ten animals were randomly selected to estimate infestation by direct visualization method. Temperature and relative humidity (RH) were recorded daily. Population fluctuation was described and periods and population peaks were identified. Pearson's correlation analysis was calculated (P < 0.05) between temperature and RH, with fly average number per animal for each population period. H. irritans infestation had fluctuations, but with presence of flies all the year; the highest infestation was observed in summer, where two population peaks were present, with 236 and 120 flies per animal, respectively; the activity in autumn and winter also showed fluctuations and the population had an increment in spring, where a population peak could be observed, as well as at the beginning of the study (156 flies/animal) and at the end (323 flies/animal). In the first population period, a significant correlation coefficient (0.93) was found with temperature, similar situation was observed in the fourth period (-0.57); no significant coefficients were found in other population periods for the climatic factors in study. [ABSTRACT FROM AUTHOR]

El objetivo del trabajo fue estudiar la fluctuación poblacional de H. irritans en un hato de ganado bovino en el municipio de Tecomán, Colima, México. El hato fue visitado semanalmente de marzo de 2003 a mayo de 2004; en cada ocasión se seleccionaron al azar diez animales para estimar la infestación mediante el método de visualización directa. Se registró la temperatura y la humedad relativa (HR) diariamente. Se describió la fluctuación poblacional presentada y se identificaron los periodos y picos poblacionales. Se realizó un análisis de correlación de Pearson (P < 0.05) entre la temperatura y la HR, con los valores promedio del número de moscas por animal para cada uno de los periodos poblacionales. La infestación por H. irritans fue fluctuante, pero con presencia de moscas durante todo el año; los momentos de mayor infestación se observaron en verano, al presentarse dos picos poblacionales, con 236 y 120 moscas/animal; la actividad en otoño e invierno también fluctuó; se incrementó en primavera, durante la cual se observó un pico poblacional, tanto al inicio del estudio (156 moscas/animal) como al final (323 moscas/animal). Para el primer periodo poblacional se encontró un coeficiente de correlación significativo (0.93) con la temperatura, algo similar ocurrió para el cuarto periodo (-0.57); no fue posible detectar coeficientes significativos en otros periodos poblacionales para los factores climáticos en estudio. [ABSTRACT FROM AUTHOR]

Se visitó semanalmente de marzo de 1999 a marzo de 2001 un establo que contaba con 510 vacas Holstein en producción y que no aplicó insecticidas durante el estudio. En cada ocasión se seleccionó 10% de las vacas en lactancia y se realizó un conteo directo del número de moscas Haematobia irritans observadas. Se calculó el número promedio semanal de moscas por vaca para identificar los periodos correspondientes al primer incremento poblacional, fluctuación, segundo incremento y decremento. Se realizó un análisis de correlación de Pearson (P < 0.01) entre el promedio semanal de moscas por vaca y temperatura, humedad relativa y precipitación pluvial, en cada uno de los periodos poblacionales. El nivel de infestación fue más alto cerca de los dos picos poblacionales, en verano-otoño, y nunca fue superior a 120 moscas por vaca. Durante el periodo de enero a marzo no se observaron moscas. En el primer incremento poblacional se encontraron altos índices de correlación, 0.80 y 0.85, para temperatura y 0.68 y 0.71 para humedad relativa, en cada año de estudio. En el decremento se observaron altos índices de correlación con la temperatura, 0.79 y 0.80. No se detectó correlación significativa con la precipitación pluvial. La temperatura influyó considerablemente en la distribución anual de la infestación por H. irritans, promoviendo o limitando los periodos poblacionales identificados. [ABSTRACT FROM AUTHOR]

A dairy farm with 510 Holstein cows in milk production, in which insecticide was not applied throughout the study, was visited weekly from march 1999 to march 2001, selecting on each occasion ten percent of the dairy cows for adult horn fly counts on direct observation. Weekly average fly numbers per cow were calculated so as to identify periods corresponding to the first population increment, fluctuation, second increment and decrement. Pearson's correlation analysis was calculated (P < 0.01) between climatic factors and temperature, relative humidity and rainfall, as well as fly counts for each of the population periods. The highest number of flies per cow was observed near the population peaks, in summer -- fall, but this was never greater than 120 flies per cow. Adult flies were not observed from january to march. High correlation indices, 0.80 and 0.85, were found in the first temperature increase, and 0.68 and 0.71 for relative humidity, in each year studied. In the decrease, high correlation indices, 0.79 and 0.80, for temperature, were found. There was not a significant correlation with rainfall. The annual distribution of H. irritans infestation was most influenced by temperature, limiting or promoting the population periods identified. [ABSTRACT FROM AUTHOR]