THE SUSCEPTIBILITY OF DIFFERENT STRAINS OF CHEYLETUS-ERUDITUS (ACARINA, CHEYLETIDAE) TO ORGANOPHOSPHATE ACARICIDES

The acaricide susceptibility of seven strains of Cheyletus eruditus, o riginating from field populations of different sources, such as grain stores, a chaff pile end pheasant fodders, was compared with that of t wo laboratory ;trains. The strain least susceptible to all the organop hosphates tested was the one that survived fumigation by PH3. The labo ratory strains and a strain from Denmark were the most susceptible. Th e 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 m ites.