%0 Journal Article
%T Seasonal Variation and Frequency Distribution of Ectoparasites in Crossbreed Cattle in Southeastern Brazil
%A Maria do Socorro Ferraz da Costa
%A Marcos Pezzi Guimar£¿es
%A Walter dos Santos Lima
%A Ana Julia Ferraz da Costa
%A Elias Jorge Facury Filho
%A Ricardo Nascimento Araujo
%J Journal of Veterinary Medicine
%D 2014
%R 10.1155/2014/759854
%X 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 months were divided into groups A ( Holstein ¡Á 3/4 Gir) and B ( Holstein ¡Á Gir) and had the monthly infestation estimated along with the climatic conditions. The mean maximum and minimum temperatures were 28.5 and 19¡ãC, respectively. The ectoparasites were present on animals in all months of the year. The levels of ticks on the animals were low ( 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 ( flies/animal) and D. hominis ( larvae/animal) on heifers was more influenced by rainfall and exhibited two population peaks during the year. Holstein heifers harbored significantly more H. irritans and D. hominis than Holstein heifers. The results are discussed considering the most appropriate periods to apply ectoparasiticides and the genetic make-up of the animals. 1. Introduction The ectoparasites of cattle in Brazil are a significant hindrance to national livestock. Among the primary ectoparasites are the tick Rhipicephalus (Boophilus) microplus and the flies Haematobia irritans and Dermatobia hominis. Together, the losses caused by these parasites are estimated at more than US$ 2.5 billion per year [1, 2]. Cattle kept under field conditions tend to be parasitized simultaneously by different species of ectoparasites. Proposals to combat more than one parasite at once are more economical and more operationally feasible and may have greater acceptance by farmers [3]. Most control programs are based primarily on the application of ectoparasiticides. The application of these compounds in a strategic manner reduces the amount of ectoparasiticides used and prevents population peaks, keeping the parasite burdens below the levels that cause economic losses. However, for satisfactory results, the number and timing of applications must take into account the biological and ecological characteristics of each ectoparasite in the region in which the program will be implemented. Another very attractive strategy is the insertion of genes from parasite-resistant breeds to use the animals¡¯ immune systems to help fight off the parasites [4]. Several studies have shown that Bos indicus is more resistant to ectoparasites than
%U http://www.hindawi.com/journals/jvm/2014/759854/