About This Project

Beneficial soil microorganisms can boost the plant immune system. We want to know if farming practices that boost the biological activity in soil can increase plant defenses against insects. We will collect soil from various farm fields, measure how well caterpillars develop on plants grown in these soils, and isolate key microbes. If farmers cultivate soil microorganisms that help plants fight off insects, they will be able to reduce insecticides use, improving health of farming ecosystems.

Ask the Scientists

What is the context of this research?

Modern farming practices like tilling and regular pesticide use can reduce diversity in agricultural soils. Regular attack by insects on modern farms drives farmers to use increasing amount of insecticides. Improving farming practices can increase soil biological activity and quality, boosting plant growth, but the effect on insect populations remains unclear. Plants themselves can defend against insects using protective chemicals. Soil microorganisms can defray costs associated with this defense by increasing the availability of nutrients and helping plants produce toxic compounds.

We are curious if farms with higher microbial activity in the soil will lead to plants that are better defended against insects, and if cultivating microbes in the soil can eventually decrease pesticide use.

What is the significance of this project?

Scientific understanding of the effects of soil bacteria, fungi and nematodes on plant defense is increasing concurrently with the adoption of ‘soil health’ practices on farms, aimed at increasing soil microbiota. However, microbial diversity due to 'soil health' has never been experimentally tied back to plant health and insect defense.

Over 83 million acres were planted with corn in the US in 2014; we will be using corn to study how soil microbes affect plant defenses because the most important crop in the US and because we understand defenses in corn very well.

If increasing microbial activity in soils helps protect plants against insects, then farmers will need less pesticides, making their crops healthier and their farms more sustainable.

What are the goals of the project?

(1) Measure microbial activity and diversity in soils that have been managed differently from farms in Pennsylvania.

We will collect soils at these farms and measure their respiration rates in an enclosed chamber. We will use 16S RNA sequencing to identify what types of bacteria are in the soil, and fungal primers to identify fungal symbionts in the soil.

(2) Measure defense activity of plants due to microorganisms in these soils.

We will grow corn seedlings in collected soils and feed them to black cutworm caterpillars (Agrotis ipsilon). We will measure the caterpillars weight gain as an indicator of plant defense. To make sure that changes in weight of these insects are due to microbes, we will compare plants grown in "living" soil and those grown in heat treated soil.