The effects of three tillage systems on soil inhabiting Gamasina (Mesostigmata : Acarina) in arable soil

The effects of three tillage practices, using broadshare cultivator, rotary cultivator and reversible plough, on soil inhabiting Gamasina were investigated between 1979 and 1982. Fifty species of Gamasina and Uropodina were found in the experimental field. Compared with the plough both cultivators stimulated a significant increase in the population of the predatory mites, especially of the Rhodacaridae and Eviphididae. The maintenance of sub-soil layers in their normal position in the profile layers also favours the populations of soil inhabiting Collembola, such as Onychiuridae and Isotomidae. Since these spring-tails are prey of gamasid mites, it is concluded that a previous increase of prey animals may have resulted in the increased population density of the predators.