Overview of Risk Factors and Strategies for Management of Insect-Derived Ear Injury and Aflatoxin Accumulation for Maize Grown in Subtropical Areas of North America

Abstract

Pest and disease risk factors causing maize yield and kernel quality issues in subtropical areas of North America (between 35°N and 23.5°N latitude) are reviewed: preharvest Aspergillus flavus (Link) (Deuteromycetes: Moniliales) infection and propagation in maize ears and ear injury principally caused by Helicoverpa zea (Boddie) and Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae). Risk is affected by potentially interacting factors of maize genetics, ear feeding with insects, fungal inoculum and growth, and weather (rainfall, temperature, and humidity). This review gives special attention to integration of the most efficient pest and disease management strategy combinations and the potential interaction of insect ear feeding and A. flavus occurrence. Management strategies reviewed include maximizing partial genetic resistance to A. flavus and selection of appropriate hybrids for the area, biological control of A. flavus using non-aflatoxigenic strains, avoiding pests and diseases using cultural practices like early planting, and reducing H. zea and S. frugiperda ear injury using Bt transgenes. Understanding the combined influences and identifying combined management approaches may lead to reduced aflatoxin risk and maintaining yield. This review focuses on subtropical areas of North America because the amount of maize produced in warm environments within or similar to subtropical maize production areas is likely to increase due to projected increases in demand for maize and predicted increases in temperature may increase pest and disease risk.