COMPARISON OF EFFECTS OF LOW AND HIGH TICK INFESTATIONS ON ACQUIRED CATTLE TICK RESISTANCE - HYALOMMA MARGINATUM MARGINATUM

Three Holstein calves were infested with low numbers of ticks, two or three pairs al adults Hyalomma marginatum marginatum in cloth bag dail y for 21 days. infestation was carried cut during tick proliferation p eriods. Two months later, cattle leads were challenged with 100 pairs of ticks. Another group of three Holstein calves were infested five ti mes with 100 pairs oi adult ricks of the same species. The five infest ations were performed two weeks from the previous infestation. Three t ick characteristics were recorded for each experiment: survival to det achment, females weight at detachment and egg mass weight. Light conti nuous infestations did not cause a significant change in this paramete r, but every parameter declined gradually in the heavy infestations. F emale and egg mass weight reached a significant difference from the fi rst infestation by the fourth infestation. The circulating antibodies anti-salivary glands of Hyalomma m. marginatum showed that light infes tation may induce like immune-suppression. However, there is an invers e relationship between these antibodies and manifestation of resistanc e when calves were heavily infested. This is discussed in relation to a fraction of produced antibodies against protective antigens, and par ticipation of another effector mechanism.