Damage to Dry Crop Seed by Red Imported Fire Ant (Hymenoptera: Formicidae)

Abstract
Red imported fire ants. Solenopsis invicta Buren, have been documented as damaging to planted field crop seed. The seeds are damaged before completion of germination. Five types of field crop seeds [wheat, Triticum aestivum L.; corn, Zea mays L.; grain sorghum, Sorghum bicolor (L.) Moench; cotton, Gossypium hirsutum L.; and soybean, Glycine max L.] were exposed to red imported fire ants under laboratory conditions to measure damage caused by feeding. The seeds were at an air-dry moisture condition, as typically sown by farmers. Corn, sorghum, and cotton seeds were tested with and without commercial insecticide treatments used on bagged retail-market seeds. Wheat was tested only as untreated seeds and soybean were tested as both inoculated and noninoculated seeds. Our results show that red imported fire ants feed on dry wheat, corn, and sorghum seeds and to a lesser degree on cotton and soybean seeds. Seed treated with an insecticide sustained less damage; however, if dry soil conditions allowed enough time for damage to exceeded 20-30%, as observed for sorghum, then there would still be a substantial risk to seed germination. Untreated wheat seed was the most heavily damaged and yet farmers in the red imported fire ant-infested region of the United States routinely plant untreated wheat seed. Red imported fire ant damage to the seeds of wheat, corn, sorghum, cotton, and soybean may vary from insignificant to severe, depending on exposure time to red imported fire ants, seed type, and whether or not a seed treatment was used.