Biological control of hard ticks, Hyalomma dromedarii (Acari: Ixodidae) using entomopathogenic nematode of two families; Heterorhabditidae and Steinernematidae was studied. The protective effect of controlled ticks including haemolymph and haemocytes against these biological agents were also investigated. It was found that heterorhabditid strains cause a higher effect in biological control of engorged female H. dromedarii than those of stienernematid strains. It induced mortality rates ranged from 12-92% versus 4-88% for stienernematid strains. It was also found that these entomopathogenic nematodes can not reproduce within the exposed ticks. SDS-PAGE of proteins extracted from midguts and salivary glands infected with 4000 IJs tick(-1) separated 21 and 25 protein bands versus 13 and 19 protein bands from non-infected ones, respectively. It was concluded that entomopathogenic nematodes of family Heterorhabditidae proved to have a potential acaricidal effect in the control of hard ticks. Moreover, the controlled ticks released unknown proteins in their haemolymph that may promote the haemocytes to phagocyte the nematodes as a type of defense mechanism.

Salivary gland (SgAg) and midgut (MgAg) antigens derived from partially fed female H. dromedarii were used to vaccinate rabbits at a dose of 100 µg/kg protein. The immunized hosts were challenged with unfed female ticks. Data revealed a significantly decreased feeding percent and duration, engorged tick and egg mass weights, number of eggs laid, hatching percent and fertility compared to control groups. Overall vaccine efficacy was evaluated as 67% and 43.79% for SgAg and MgAg, respectively, that means tick Ags used induced best protection against H. dromedarii population. Immunogenicity of experimental vaccine homogenates revealed a strong and specific immune response against both antigens. Western blot analysis revealed that 7 polypeptide bands ranging in their molecular weights from 95.8 to 32.3 kDa were recognized in SgAg, whereas 10 polypeptide bands ranging from 93.7 to 8.6 kDa were identified in MgAg.

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