Effects of microwave and various combinations of ambient temperature and humidity exposures on off-host survival of northern fowl mites.

When northern fowl mites, Ornithonyssus sylviarum (Canestrini and Fanzago), were removed from their host and exposed to ambient temperatures ranging from -15 to 49 C with uncontrolled relative humidity (RH) or to temperatures ranging from .3 to 38 C with an RH of ca. 75%, mites lived longest at 4 C. However, temperatures between .3 and 26 C were also conducive to survival. Temperatures above 43 C killed the mites in less than 5 hr; mites exposed to -15 C lived up to 5 days. A constant humidity of ca. 75% was most beneficial to the mites when temperatures ranged from 33 to 38 C. Manipulation of ambient temperature and RH would be effective in exterminating the northern fowl mites on inanimate objects. Mites exposed for different periods to microwave energy at a net power ranging between 165 to 430 kw/m2 were not selectively heated to temperatures above the temperatures of the containers, nor did the irradiation have any other lethal effects on the mites.