The aims of this study were to evaluate the seasonal variation and frequency distribution of Rhipicephalus (Boophilus) microplus , Haematobia irritans , and Dermatobia hominis on crossbred heifers under field conditions in the northeast of Minas Gerais state, southeastern Brazil. From November 2007 to September 2009 (23 months), 40 heifers aged 16.6±2.4 months were divided into groups A ( 1/4 Holstein × 3/4 Gir) and B ( 1/2 Holstein × 1/2 Gir) and had the monthly infestation estimated along with the climatic conditions. The mean maximum and minimum temperatures were 28.5 and 19°C, respectively. The ectoparasites were present on animals in all months of the year. The levels of ticks on the animals were low ( 3.0±0.2 ticks/animal), with the highest density in midwinter. The temperature was the climatic factor that most influenced the tick levels. The population of H. irritans ( 13.9±0.3 flies/animal) and D. hominis ( 1.5±0.2 larvae/animal) on heifers was more influenced by rainfall and exhibited two population peaks during the year. 1/2 Holstein heifers harbored significantly more H. irritans and D. hominis than 1/4 Holstein heifers. The results are discussed considering the most appropriate periods to apply ectoparasiticides and the genetic make-up of the animals.
Ferraz da Costa, M. do S., Guimarães, M. P., Lima, W. dos S., Ferraz da Costa, A. J., Facury Filho, E. J., & Araujo, R. N. (2014). Seasonal Variation and Frequency Distribution of Ectoparasites in Crossbreed Cattle in Southeastern Brazil. Journal of Veterinary Medicine, 2014, 1–8. https://doi.org/10.1155/2014/759854