Resistance of Purebred Brahman, Hereford, and Brahman x Hereford Crossbred Cattle to the Lone Star Tick, <i>Amblyomma Americanum</i> (Acarina: Ixodidae)

Abstract

Abstract Differences in resistance to the lone star tick, Amblyomim americanum, between Brahman and European breed cattle were compared. Purebred Hereford, purebred Brahman, and Brahman X Eereford crossbred steers were infested 3 times with 300 male and 300 female ticks per animal. Number and weight of replete female ticks dropped from each animal, as well as the percentage of eggs hatched were used as criteria of resistance. The number of female ticks feeding to repletion on an animal was found to be positively correlated with the weight of the replete ticks. All test cattle acquired a high level of resistance to the lone star tick by the 3rd cycle of infestation as indicated by significant reduction in numbers and weights of replete female ticks. The average number and weight of engorged female tioks per animal suggest that the purebred Hereford steers were considerably less resistant than both the Brahman X Hereford crossbred steers and purebred Brahman steers. Hatchability of eggs from female ticks fed on purebred Brahman steers was significantly lower than that of eggs from females fed on purebred Hereford and Brahman X Hereford crossbred steers.