Plant Health Program, Doctor of


First Advisor

Gary L. Hein

Document Type

Doctoral Document

Date of this Version



Braley, Callie, "The Impact of Beneficial Organisms in Corn Agroecosystems" (2021). Doctoral Documents from Doctor of Plant Health Program. 19.


A Doctoral Document Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Plant Health, Major: Plant Health, Under the Supervision of Professor Gary L. Hein. Lincoln, Nebraska: December, 2021

Copyright © 2021 Callie Rosalind Braley


Corn is one of the world’s, and Nebraska’s, most important crops. Millions of acres are planted to corn each year in the Cornhusker State. However, each year there are a plethora of arthropod, weed, and microorganism pests that rob farmers of reaching their maximum yield potential. There are many options available to manage these pests in corn agroecosystems, but one option is often underutilized: beneficial organisms. For each pest, there are a variety of natural enemies that can assist in mitigating the damage caused by pests.

Many beneficial organisms exist, and they can be grouped by the type of pest they target: arthropods, weeds, or pathogens. Natural enemies in each of these groups range from large and conspicuous to microscopic. For example, lady beetles and nematodes can prey upon arthropod pests, ground beetles and certain fungi help control weeds, and some mites and bacteria target plant pathogens.

Beneficial organisms should be one tool used in Integrated Pest Management (IPM) programs. Taking advantage of natural enemies is more important than ever due to pesticide bans and resistance. Conservation biological control, which is readily available and relatively easy to implement, is one way farmers can maximize the impact of beneficial organisms. This method of conserving natural enemies can be achieved by reducing pesticide use or using selective pesticides, conserving and planting vegetation to supply resources to beneficials, using less-toxic pest management alternatives (e.g., planting Bt corn), and adopting reduced tillage practices such as no-till to preserve essential resources.

One important example that highlights the impact of beneficial organisms in corn agroecosystems is their role in the management of spider mites, which are often a problem in hotter and drier areas. While there are other methods available to manage spider mites, some of these, such as pesticides, can be harmful to beneficial organisms. Therefore, growers and agronomists must consider multiple factors when creating and implementing IPM programs.

Advisor: Gary L. Hein