K-State professor helps find a natural alternative to chemicals
Stored-product pests are millers' worst nightmares. But one Kansas State University researcher is working to show there are ways to get rid of these pests without harming the environment or the budget.
Since the late 1940s, methyl bromide fumigation had been the method of choice for controlling insects in mills, according to Subramanyam Bhadriraju, professor of grain science and industry at K-State. However, this gas was shown to deplete the ozone and was phased out in the U.S. in 2005--although it is still available for certain exempted uses, such as for preshipment and quarantine and for certain user groups.
Bhadriraju has turned back in time to a technique that has been around for the past 100 years but was abandoned when methyl bromide came on the scene. The "new" method is heat treatment and Bhadriraju has been working since 1999 to re-examine it as an alternative to the use of methyl bromide.
Heat treatment involves raising the ambient temperature of an entire mill or a portion of it to 122 degrees to 140 degrees Fahrenheit, and holding these high temperatures for 24 hours or less. The treatment can be done with electric, steam or gas heat, Bhadriraju said.
Although he had literature to look back on to find out more about the high-temperature treatment, Bhadriraju said there was limited quantitative information on how the process works and its effectiveness on insects. He has performed research on and taught the process to different audiences through six heat treatment workshops. Some of the aspects Bhadriraju has looked at are the amount of energy needed to heat a mill and minimum temperature and exposure time needed to kill life stages of various mill insects. He is also looking at how to get uniform heat distribution within a mill, and methods to remotely monitor temperatures so that corrective action can be taken in "real time" to make heat treatment effective.
Bhadriraju has found heat treatment for killing insects does not harm the environment and is great to use in small areas instead of shutting down an entire mill. However, it does take a certain finesse to figure out how to use it, since each mill treated is structurally different.
"Heat treatment is mostly art," Bhadriraju said. He encourages millers to try the process at least once.
"Every time you do it you'll learn something more," he said. "Lots of people are embracing it, such as organic food companies. I have a feeling it will get a second life."
The only barrier to wider use, Bhadriraju said, is a lack of economic analysis on the process--some think it is too expensive.
In addition to mills, heat treatment can also be used for empty warehouses and empty concrete or round metal bins. The process could also potentially be used in pet stores, pasta plants, bakeries and kitchens, he said.