History and complexity in tick-host dynamics: Discrepancies between 'real' and 'visible' tick populations

Background: numerical responses of ticks to changes in densities of their hosts can be complex and apparently unpredictable. manipulations even of deterministic models can produce counter-intuitive results,including tick populations that either rise or fall under increasing host densities,depending on initial conditions. methods. in this paper i use an established simulation model to demonstrate a wide range of numerical responses to different scenarios of host changes,and to examine the basic mechanisms that drive them. results: the rate and direction of change of host densities affects the extent to which questing tick numbers reflect those of their hosts. numerical responses differ profoundly between dynamic tick-host systems and those allowed to reach equilibrium. conclusions: the key to understanding tick-host dynamics is to understand the difference between 'real' and 'visible' tick populations. an appreciation of the implications of this difference - and of the conditions that influence it - will benefit the effective interpretation of field data. © 2014 dobson; licensee biomed central ltd.