The susceptibility of different strains of Cheyletus eruditus (Acarina: Cheyletidae) to organophosphate acaricides

The acaricide susceptibility of seven strains of Cheyletus eruditus, originating from field populations of different sources, such as grain stores, a chaff pile and pheasant fodders, was compared with that of two laboratory strains. The strain least susceptible to all the organophosphates tested was the one that survived fumigation by PH3. The laboratory strains and a strain from Denmark were the most susceptible. The use of the population of C. eruditus with the lowest susceptibility to organophosphates is desired in the management of acaroid mites. It is intended that mites of this strain will be mass reared and used for dissemination in grain stores for the biological control of acaroid mites.