MECHANISMS OF MICROARTHROPOD MICROBIAL INTERACTIONS IN SOIL

This chapter provides an overview of the mechanisms of microarthropod by focusing on the microbial interactions in soil. Microarthropods control the distribution and abundance of fungi in soil, and they stimulate microbial metabolic activity, thereby amplifying microbial immobilization or mineralization of nutrients. Microarthropods are important as vectors of entomopathogenic fungi to holometabolous insects. In soils where fungi dominate, there are six mechanisms of interaction with microarthropods. Two control fungal distribution and abundance––namely, selective grazing of fungi by microarthropods and dispersal of fungal inoculum by microarthropods. Four additional mechanisms stimulate microbial activity: (1) direct supply of mineral nutrients in urine and feces, (2) stimulation of bacterial activity by microarthropod activity, (3) compensatory fungal growth due to periodic microarthropod grazing, and (4) release of fungi from competitive stasis due to microarthropod disruption of competing mycelial networks. Microarthropods carry fungal propagules, including those of root pathogens, to root surfaces. They also graze fungi on root surfaces, and selectively consume saprophytic fungi. In the rhizosphere, the mechanisms of interaction are dispersal and selective grazing. Simulation models of soil food webs might include responses to microarthropods. © 1992, Academic Press Limited