| Summary: | 碩士 === 靜宜大學 === 生態人文學系 === 102 === The tropical fire ant (Solenopsis geminata) has been introduced into Taiwan for many years, and was widely distributed in Central and Southern Taiwan. S. geminata tends to invade open and disturbed areas. Because of their granivorous habit (dyszoochory), S. geminata workers were observed to attempt collecting seeds from numerous plant species. The study was conducted in Taichung, Yunlin, Chiayi and Tainan. We excavate fire ant nests to find seeds which collected by ants. All collected seeds were sorted and identified to species. A total of 37 seed species in 12 plant families were collected by fire ants from the four areas in Taiwan. Most of these seeds are herb seeds, especially the Poaceae including 16 species. Three species of seeds from tree and shrub were found in the nests. They are Broussonetia papyrifera, Flueggea virosa and Solanum torvum. A large quantity of seeds collected by fire ants was Panicum maximum in Taichung; Chamaesyce hirta, Eleusine indica and Paspalum conjugatum in Yunlin; Pouzolzia zeylanica, Chamaesyce hirta and Dichanthium annulatum in Chiayi; Amaranthus patulus, Dactyloctenium aegyptium and Digitaria sanguinalis in Tainan. In seed preference experiments, grass seeds, such as Dichanthium annulatum, Panicum maximum, and Paspalum orbiculare were readily removed by fire ants. In contrast, fire ants appear to less prefer seeds from forbs, such as Chamaesyce hirta. Moreover, larger seeds were removed by ants more often than smaller ones. In seed germination experiments, the germination rates of seeds from Pouzolzia zeylanica, Dactyloctenium aegyptium, Panicum maximum and Paspalum conjugatum collected by fire ants were significantly higher than that from the mature seeds on the plants. The germination rates of seeds from Chamaesyce hirta, Dichanthium annulatum and Digitaria sanguinalis revealed no significant difference between nest and plant. The germination rates of seeds from Amaranthus patulus was significantly lower than that from the mature seeds on the plant. The results in this study show that seed removal by workers of S. geminata may has impacts on the plant community, especially grasses in fields infested with S. geminata in Taiwan.
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