Did alien ants initiate a population explosion of a coccoid plant pest on an islet in the Coral Sea?
The composition of the ant fauna of a Coral Sea islet, North East Herald Cay, is reported for several years from 1995 to 2007. A major change in composition was first noted in 2007 but probably occurred earlier. Tetramorium lanuginosum, present in 1997 and in previous years, was not found in 2007. Instead, Tetramorium bicarinatum, recorded for the first time in 2006, was abundant in 2007. This change, together with drier conditions, may have initiated a population explosion of a pest coccoid that caused serious damage to the tree, Pisonia grandis. Tetramorium bicarinatum also reduced the abundance of surface-active arthropods compared to their abundance when it was absent. Ants and other invertebrates on three other islets in the Coral Sea are also documented for 2007 and support the dominance effects of T. bicarinatums.