Soil abiotic factors impact Metarhizium spore movement and biological control capacity

Entomopathogenic fungi such as Metarhizium spp. are ubiquitous soil organisms that are well known for their ability to infect and kill insects. Because the soil is the main habitat and reservoir of Metarhizium, it is expected that soil abiotic and biotic factors will impact the vertical movement of spores as well as their biological control capacity. Although studies have reported varying effects of soil texture, porosity, and organic matter (OM) on the occurrence and abundance of EPF in native soils, there have been few attempts to quantify the effects of these edaphic factors in controlled laboratory settings. In this experiment, we used soil columns constructed of varying degrees of sand, native soil, and OM to manipulate the soil texture, porosity, and percentage of OM within each column. We quantified the number of spores, spore viability, and Metarhizium biological control capacity using Galleria mellonella bioassays at three different depth sections within each column. Additionally, we quantified spores that drained through each column, as well as a variety of soil physical and chemical properties. The results of this study will allow us to gain insight into the interactions between Metarhizium spores and specific abiotic soil properties.