Factors affecting the on-host distribution of northern fowl mites, Ornithonyssus sylviarum

Northern fowl mites on hens tend to be restricted to the vent region. The distribution is likely to reflect variation in temperature, humidity, and light levels. Mites were placed onto gradients where they could settle on a continuous range of temperatures (20-50 C), in specific zones of humidity (31%, 65%, 85%, and 100%), or were given a choice of darker versus lighter areas to arrest. Preliminary results show the mites prefer a temperature between 31 and 34 C and that they tend to avoid light. Results of the off-host assays will be presented and compared with the mite positions on host feathers as a function of temperature.