Asymmetrical competition and amensalism through soil dumping by the ant, Myrmicaria natalensis

ABSTRACT.

• 1 Myrmicaria natalensis (Smith) (Hym: Formicidae) is a large, predaceous ant that excavates large amounts of soil during nest construction.
• 2 During the winter, 25% of its nests went extinct through resistance and aggression from allospecific ants. The remaining 75% thrived, although one nest was forced to move, but did not go extinct, through intense competition.
• 3 The surviving fifteen M.natalensis nests obliterated forty-one allospecific nests by covering them with excavated soil.
• 4 During spring, M.natalensis nests expanded rapidly and none went extinct, so there was no longer asymmetrical competition but total amensalism in favour of M.natalensis.
• 5 Implications for ant management are that control by trunk banding of honeydew-seeking ants will increase asymmetry towards M.natalensis through positive feedback. This is desirable in that M.natalensis is a highly predaceous ant of pests such as lepidopteran larvae.