Ticks are obligate blood feeders. All active stages require blood as a source of nutrition and, in the case of adults, for sperm or egg production. Because of the mechanical processes and salivary secretions associated with blood feeding, the tick-host parasitic interaction is complex.
Some tick species only feed on specific hosts; these are called host-specific ticks like the cattle tick Boophilus microplus, a one host tick. They are specialists.
The second category represents the opportunistic ticks, which are considered as generalists. For example, Amblyomma americanum attacks mammals, birds and reptiles (Sonenshine, 1991). Furthermore Ixodes ricinus is known to have a wide host-spectrum. This forms the reservoir for tick-borne diseases, including the risk to transmit new pathogens to a host, that has not been reported before. The most relevant ticks for companion animals are three-host-ticks. The prevalence of ticks with tick-transmitted pathogens and the prevalence of reservoir animals increases the risk of companion animal to become infected (Hartig, 1991).
A contact between ticks and hosts is regulated by at least 5 conditions. They consist of seasonal and daily effects (abiotic parameters) like day length, temperature, humidity. The rest includes biotic parameters as biological processes within the tick, the biological processes within the host and interactions between these two groups.
- Sonenshine DE: Biology of Ticks. Part 1, 1991, Oxford UniversityPress, New York
- Hartig AJ: [About the epidemiology of Ixodes borreliosis in southwest France.] 1991, Dissertation, University of Munich, [in German]