Studies on Host Resistance by Some Breeds of Cattle to Ticks (Ixodoidea, Ixodidae) with Special Reference to Hyalomma Anatolicum Anatolicum

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Date
2015-06-23
Authors
Abdullahi Abdel Latif Ibrahim, Ibrahim
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UOFK
Abstract
Hyalomma a. anatolicum in the field is considered to have a 3-host feeding cycle, but in one location (University Farm at Shambat) the larvae feeding on the back of calves, in the winter season, showed a 2-host feeding cycle. Immature of H. a. anatolicum, A. lepidum, A. variegatum and R. evertsi were found to feed on cattle. Whole body tick collection carried out at 6-day intervals for 2 months at Nisheishiba, indicated significant differences in tick counts between three breeds of cattle. The crossbred cows carried 4.5 times more ticks (mean tick count 70.5 ± 84.8) than Kenana (mean tick count 16.7 ± 24.4) or Butana cows (mean tick count 15.0 ± 18.4). In all cases standard deviations were larger than the means reflecting the normal variance in tick numbers between individuals. Thus, 20% of crossbred or Kenana cows carried 45-48% of total tick count for the breed but there was more uniformity in Butana cows (28% of cows carried 36% of ticks). When the whole herd was considered (22 cows) only 9% of cows (2 cows) carried 51% of the total tick infestation. Therefore, culling or regular spraying of only the 2 susceptible cows would eliminate half of the total number of ticks carried by that herd. Significant differences also existed in degree of engorgement achieved by H. a. anatolicum ticks on different breeds of cattle. Weight of detaching fully engorged females feeding on Kenana and crossbred cattle was 374.8 mg and 422.0 mg, respectively. This was reflected in the amount of eggs laid by the females which were 191.3 mg for the Kenana fed ticks and 261.1 mg for those fed on crossbred. The resulting larval challenge from the crossbred fed ticks was 27% greater than the ticks fed on Kenana cattle. A 100 nymphs test for evaluation of resistance of cattle to ticks was designed and found to have a good potential for assessing the resistance status of cross-bred cows. Thus, 10% of nymphs engorged on the resistant host with mean engorgement weight of 11.3 mg compared to 20% and 45% of engorged nymphs on the 2 susceptible hosts with 15.8 mg and 13.6 mg mean engorgement weights.
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Studies on Host Resistance by Some Breeds of Cattle to Ticks (Ixodoidea, Ixodidae) with Special Reference to Hyalomma Anatolicum Anatolicum
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