Plant probiotics? Understanding how soil health practices influence plant-insect interactions

View the project final report

• 2016 annual report

Commodities

• Agronomic: corn

Practices

• Crop Production: cover crops, no-till
• Education and Training: extension
• Natural Resources/Environment: soil stabilization
• Pest Management: biological control, cultural control, integrated pest management
• Soil Management: organic matter, soil analysis, soil microbiology

Soil health practices, such as cover cropping and reducing tillage, improve physical characteristics of soil, but also appear to increase microbial community diversity. Importantly, by changing the nutritional quality or anti- herbivore defenses of host plants, some soil microbiota can influence the damage that insect herbivores cause to plants. However, research in this area has typically focused on particular microbial inoculants. We propose to take a community approach encompassing microbes (bacteria and fungi) and natural enemies of insect herbivores to examine how agronomic practices influence beneficial organisms that can modulate levels of damage by plant-feeding insects. We will first determine if indigenous microbial communities in no-till and cover-cropped fields influence insect damage, and compare their effects to that of microbes in conventionally- managed soils. We will conduct a greenhouse study in which we will grow corn plants in soil collected from farms with different degrees of “soil health.” To isolate the influence of microbes, we will pasteurize half of these soils and assess how corn plants grown these soils resist herbivory. Second, in a field experiment with corn we will examine how herbivore damage and predator abundance are influenced by inorganic fertilizers (NPK) and a mixture of manure and compost. This work is fundamental for understanding how insect crop damage may be affected by soil health practices, and will provide insight for farmers about how management practices meant to improve soil quality can also decrease risks from plant-feeding insects.