Mechanisms of host-tick contact with special reference to Amblyomma americanum (Acari: Ixodidae) in beef cattle forage areas.

At least five groups of parameters regulate contact between ticks and host animals. Group 1 (seasonal effects) and group 2 (daily effects) comprise abiotic parameters and include daylength, temperature, relative humidity, and interactions thereof. Groups 3, 4, and 5 consist of biotic parameters. These pertain to biological processes in ticks (group 3), such as hunger responses and spatial patterns in aphagous tick populations; biological processes in host animals (group 4), such as patterns of habitat use by host animals; and interactions between host animals and ticks (group 5). Host-tick contact is possible when ticks are hungry, when ticks exhibit a positive appetence response, and when ticks and host animals are together in time and space. A descriptive model is proposed to correlate these processes and interactions with the observed behavior of the host-tick contact system in nature. Emphasis in the model is placed on host activity and differences among host types.