FEEDING PERFORMANCE AND SURVIVAL OF AMBLYOMMA-AMERICANUM (ACARI, IXODIDAE) ON RESISTANT BOS-TAURUS AND BOS-TAURUS X BOS-INDICUS CROSSBRED HEIFERS

Host resistance to lone star ticks, Amblyomma americanum (L.), was developed in Hereford (Bos taurus) and Braford (F1, 1/2 B. taurus X B. indicus) crossbred heifers through artificial infestation of adult ticks. The feeding success of known numbers of larvae, nymphs and adults was determined. Significantly fewer larval, nymphal or female ticks successfully attached or fed on resistant Braford than successfully attached or fed on resistant Hereford. A cumulative estimate of the effect of host resistance on tick feeding performance and survival was calculated by multiplying the proportion of each stage successfully feeding and surviving to the next stage. The estimated cumulative survival of lone star ticks ranged from 0.01 to 0.44% for ticks fed on Braford, and from 0.5 to 4.3% for ticks fed on Hereford. Resistant Braford had a greater cumulative effect on the feeding performance and survival of lone star ticks than did resistant Hereford.