Soil legacy of cover crops on corn leaf aphid (Rhopalosiphum maidis) performance and host preference

Research Poster Health & Life Sciences 2025 Graduate Exhibition

Presentation by Anju Poudel

Copresented by Anju Poudel

Exhibition Number 39

Abstract

The dynamic interactions between soils, plants, and microorganisms underpins ecosystem vitality, influencing both plant growth and resilience to pest insects. Plant-soil feedback can influence plant chemistry and plant-herbivore interactions. Cover cropping, a common agricultural practice, leaves a legacy effect that alters soil carbon (C) to nitrogen (N) ratio, impacts herbivory resistance in maize, and can influence soil microbiomes. However, research on cover crops’ soil legacy effects on corn leaf aphid (CLA), Rhopalosiphum maidis, is limited. To address this gap, we tested maize grown in soils from legume-Austrian winter pea (Pisum sativum L.), non-legume broadleaf- forage radish (Raphanus sativus L.), grass- triticale (x Triticosecale), and potting mix as a control. Two corn varieties, MC4050 and B73, were grown on these soils evaluate responses to these soil legacies. We hypothesized that cover crops impart soil legacy effect conferring subsequent crop plant defense, thereby influencing defense against aphids. Eight treatments, using autoclaved and non-autoclaved soils, were used to tease apart the role of soil microbes from soil nutrients in aphid responses to different cover crop soils. Ten adult aphids were introduced on the corn plant and the aphid population was monitored. Plant volatile organic compounds were collected from each plant to understand the effect of cover crops on corn direct and indirect defenses against aphids. Our findings suggest that irrespective of sterilization, field soil, regardless of which cover crop was present, reduced CLA populations. Future approaches will focus on investigating microbial shifts in cover crop soil that contribute to maize defense against corn leaf aphids.

Importance

This study highlights how farming practices, like cover cropping, can strengthen corn plants' natural defenses against pests like aphids. By exploring how different cover crops affect soil health and plant resistance, this research uncovers ways to reduce pest damage without relying heavily on chemical pesticides. It shows that soils influenced by previous crops can improve plant resilience, even without soil sterilization. These findings have practical implications for sustainable agriculture, helping farmers improve pest management through natural soil-plant interactions. Understanding how soil microbes and nutrients contribute to plant defense can lead to healthier crops, lower pest risks, and reduced chemical use, promoting both productivity and environmental stewardship in farming systems.

DEI Statement

My research explores the impact of cover cropping on soil health and plant resistance, focusing on how these practices benefit farmers with limited access to chemical pest control. This work addresses economic and environmental inequalities in agriculture by promoting sustainable pest management solutions that are accessible to small-scale and underserved farming communities. By investigating natural plant defenses and the role of soil microbiomes, my study supports equitable farming practices that reduce dependency on costly inputs. Additionally, it recognizes the importance of diverse, culturally relevant agricultural knowledge systems, particularly for marginalized communities who rely on traditional methods. This research aligns with DEI by advancing inclusive, sustainable strategies that improve food security and promote environmental justice across diverse agricultural landscapes.