Life Cycle of Hyalomma dromedarii Ticks (Acari: Ixodidae) on Sheep under Experimental Conditions

Abstract

Aims: This experiment aimed to study the life cycle of Hyalomma dromedarii fed on sheep under experimental conditions. Place and Duration of Study: The study was conducted between June and October 2018 at Atbara Veterinary Research Laboratory, Atbara, River Nile state, Sudan. Methodology: Nine sheep were purchased from the local market and used as hosts for feeding H. dromedarii (larvae, nymphs and adults) using the ear bags method. After feeding, detached engorged larvae, nymphs and adults were maintained under laboratory conditions at 25°C and relative humidity (R.H) 75%. All information including feeding periods, the number of engorged and detached ticks (larvae, nymphs and adults), pre-moulting and moulting periods, preoviposition and preeclosion periods were recorded daily. Results: 93.3% of larvae (1400/1500) successfully complete their feeding during a period between 3-17 days at 34.5°C and (R.H) 47%. The pre-moulting and moulting periods of larvae were between 12 -13 days and 2-3 days, respectively. Regarding the nymph stage, 96% of nymphs (288/300) completed their feeding between 3-10 days at 27.4°C and (R.H) 56%. The nymph took between 13-15 days as pre-moulting period, while the moulting period was 3-4 days. All adult ticks, 100% (30/30) completed their feeding successfully on sheep during a period between 4-10 days at temperatures ranging between 33-35°C and (R.H) ranging between 36-41%. The preoviposition and preeclosion period varied between 4-6 days and 16-21 days, respectively. The average of engorged ticks' weight, number of eggs produced and the weight of mass eggs were 396.6 mg, 3530 eggs and 217.84 mg, respectively. Regarding hatchability, the results revealed that more than 97.3% of eggs were able to hatch and produce larvae. Conclusion: This study showed that H. dromedarii behaved as a three-host tick and completed its life cycle between 94- 140 days. The results confirmed the positive relationship between the weight of the engorged female and the number of egg laid, as increases in the females’ weight were associated with an increase in the number of eggs.