By Andi Anderson
A student research project at Iowa State University has brought new attention to the destructive impact of maize weevils on stored grain. Graduate student Keith Urmie first began studying the insect during his undergraduate years, where he completed an Honors capstone project in agricultural engineering focused on measuring how much damage the pest can cause.
Reflecting on the study, Urmie said, “The big thing that I discovered through this research was how destructive maize weevils are.”
Maize weevils are tiny insects that pose major threats to stored maize, particularly in warm regions such as Africa, Haiti, and Honduras. Adult weevils lay their eggs inside maize kernels, and the larvae feed on the endosperm, often leaving behind only the hulls.
Under the guidance of Carl Bern, emeritus university professor of agricultural and biosystems engineering, Urmie set out to determine how much maize a single weevil can consume each day under ideal conditions.
Working with 48 maize samples kept in a controlled environment, Urmie monitored weevil activity over two storage periods. After 50 days, he opened half the samples to record weevil numbers and maize mass.
After 30 more days, he examined the remaining jars to calculate consumption rates. He also studied moisture generated by weevils and the resulting mold growth. The goal was to support better storage methods for small-holder farmers and to contribute to Bern’s long-term grain storage research.
One striking result showed that an initial infestation of 25 weevils could grow dramatically. Under ideal conditions, this population could reach 193 million weevils in one year and consume 20 tons of maize stored at 15% moisture.
Urmie appreciated the trust placed in him throughout the project, noting, “The biggest thing for me was being able to own my own study as an undergraduate student.”
Bern also values giving students ownership of projects, saying, “We’re unique here in the Department of Agricultural and Biosystems Engineering in how we treat our students. They’re going to have their own project and they’re going to be responsible for it.”
Urmie hopes future students will continue exploring how weevil density and environmental factors affect storage outcomes. As he said, “I worked with other undergraduates on this study, so teaching-wise, it was a very good experience to be able to pass this on to someone else and show them what this research is all about.”
Photo Credit: iowa-state-university
Categories: Iowa, Education