Factors Affecting Sorghum and Corn Seed Predation by Foraging Red Imported Fire Ants (Hymenoptera: Formicidae)

Abstract

A description of red imported fire ant, Solenopsis invicta (Buren), damage to corn, Zea mays L., and sorghum, Sorghum bicolor (L.), seeds is presented with results of laboratory experiments. Worker ants damaged seeds by rasping through the pericarp at the germ portion of seed and removing the embryo (germ). Occasionally, the pericarp was removed and/or the leaflet and root tissue were damaged. Only rarely was the endosperm consumed. Ants damaged dry seeds, but water-soaked or germinating seeds were damaged at a higher rate. When ants were offered flour of ground embryo and ground endosperm, the embryo portion was consumed more quickly. In simulated plantings, seeds with the embryo portion inaccessible to foraging S. invicta were rarely damaged. Numbers of seeds damaged during a limited exposure period were correlated with colony size in laboratory colonies. Colonies initially unresponsive to sorghum seeds and deprived of food or water increased their consumption of sorghum seeds relative to colonies receiving a normal schedule of artificial diet. Results confirm observations of fire ant damage in field situations.