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Friesian cattle were immunized with two inoculations of anti-tick Bm86 (Tick-GARD) vaccine and were challenged 30 or 90 d later with Boophilus annulatus larvae derived from 1.2 g of eggs. No nymphs or adult ticks were found on the immunized cattle during four weeks after challenge. Repeated infestations (2 to 4) with larvae on three other calves during a period of 160 and 390 d after the immunization did not result in development of nymphal and adult stages. In control, non-immunized cattle infested with corresponding batches of larvae 1380 to 4653 replete adult female ticks were collected. Larvae issued from Babesia bovis-infected female ticks transmitted the infection to Bm86-immunized cattle, but the progeny of B. bigemina-infected females did not. Since B. bigemina is transmitted exclusively by nymphal stages of Bo. annulatus these results support the observation that immunity induced by Bm86 affects the larval stage of this tick.

A 2 year survey of ixodid ticks in the Judean area of Israel between 1983 and 1985 showed that sheep were parasitized by the following species: Rhipicephalus sanguineus group (30.6%), Rhipicephalus bursa (25.3%), Haemaphysalis cretica (20.5%), Haemaphysalis otophila (20.1%) and Hyalomma anatolicum excavatum (3.1%). Three other species, Hyalomma marginatum rufipes, Boophilus annulatus and Amblyomma lepidum were also present but in very low numbers. A total of 50,816 specimens (78.1% adult ticks) were collected from the sheep. In the field, a total of 4780 ticks (8.7% adults) were collected and 64.3% consisted of R. bursa. Other species found were H. cretica (14.5%), H. a. excavatum (13.7%), H. otophila (3.4%), R. sanguineus group (1.9%) and 1.7% was Ixodes eldaricus. The number of ticks collected varied from year to year and seasonal activity was observed in all species except for H. a. excavatum. In all species, males outnumbered females, with the exception of H. cretica. The seasonal occurrence, tick ecology and disease relationship is discussed for each species.

The seasonal distribution of the tick Rhipicephalus bursa in sheep has been studied during one year in two neighbouring flocks of Awassi sheep in an enzootic focus of sheep babesiosis. Rates of tick infestation on the two flocks were very different. Pre-imaginal stages were found on the sheep during the winter months of November-March while adult ticks appeared in the middle of April and persisted until the end of July. First clinical cases of babesiosis in sheep were diagnosed 2 weeks after finding the first adult ticks. The pre-imaginal stages were found mainly in the pinnas while adult ticks preferred in decreasing order the tail, body and head. Few adult ticks were found on the legs.