Fungal Feeding or Oribatid Mites (Acari: Cryptostigmata) in an Aspen Woodland Soil

Abstract

The feeding ecology of five oribatid mite taxa from an aspen woodland soil was examined. Ceratozetes kananaskis, Ceratozetes gracilis, and Scheloribates spp. were predominant in the fermentation (F) and humus (H) horizons while Eremaeus spp. and Eupterotegaeus rostratus were restricted to the litter (L) horizon. In laboratory studies the five mite taxa were fed and reared upon the seven most common fungal species which had been isolated from the aspen soil. The mite inhabitants of the F and H—horizons showed variation in amount of feeding and reproductive success among the fungi tested. There was no direct relationship between the amount of mite feeding and reproductive success on any given fungus. The L inhabitants fed very little on fungus in culture and showed no reproduction. Gut content analyses from field specimens showed that all taxa fed on fungi and demonstrated that laboratory feeding studies were a poor indication of feeding type. All taxa fed predominately on the pigmented fungi with the F and H inhabitants showing a higher proportion of hyaline fungi than the L inhabitants; this difference was probably related to the fungal distribution in the soil. Seasonal variation in amount of gut contents was directly related to a postulated level of microbial activity in the soil. Only 2% of the fungal standing crop would be consumed in 1 yr by the total oribatid mite community emphasizing the importance of assessing the effect of the oribatid mites in conjunction with the other mycophagous members of the soil fauna. Possible interactions between oribatid mites and the fungal community were given and the consequences of the interactions related to organic matter decomposition.