Rice seeds in the United States are susceptible to damage from an insect called the rice water weevil, but Mississippi State University researchers have found that crops suffer less damage when pre-treated with neonicotinoid pesticides.
"There was no observed yield or economic benefit from the use of an insecticidal seed treatment in areas of low pressure," the study authors said. However, "all seed treatments showed an economic advantage in areas of high weevil pressure."
The study, published in the Journal of Economic Entomology, confirms that economic threshold – the pest density when action should be taken to prevent more pest from destroying crops – is key to Integrated Pest Management.
"The problem with rice water weevil is that it does not infest the field until it is flooded, about three to five weeks after planting," Jeff Gore, co-author of the study, said. "Based on most of our research, we see an economic benefit of neonicotinoid seed treatments on 70-80 percent of the rice grown in the state annually. Unfortunately, we are not able to accurately predict which fields will have a significant infestation because of when infestations occur relative to when the crop is planted. As a result, we recommend a seed treatment on all of our rice in Mississippi."