How many queens are there in mature colonies of the green ant, Oecophylla smaragdina (Fabricius)?

Abstract

In an ongoing study of the green ant, Oecophylla smaragdina (Fabricius), to control insect pests, we surveyed newly established ant colonies in a 3-year-old mango block in March 1997 at Howard Springs Northern Territory. We also surveyed 12 established ant colonies from May to July 1997 in Darwin and six of them were surveyed again in February 1998. The aims were to determine patterns of initial colonisation by dealate queens of O. smaragdina and to locate the queen ant nest in established colonies of the ant. The number of dealate queens in new communal nests varied from one to 15. In a total of 73 nests, 71% of nests contained more than one dealate queen and 12% of nests contained segments or corpses of dealate queens, which were either parasitised by a fungus or killed by predators This confirms that pleometrosis during the initial establishment of a colony is very common in O. smaragdina, and suggests that natural enemies affect the success of initial colonisation. Of 12 established green ant colonies, 10 colonies with two to six queens were all in one nest, and only two colonies had one queen. In those colonies with multiple queens, we found that each queen was almost equally attractive to the major workers. Contrary to previous reports, these data suggest that pleometrosis in O. smaragdina during the initial period of colony establishment can lead to polygyny in mature colonies. This is the first time that polygyny has been documented in mature colonies of O. smaragdina.