Short-Term Change in a Population of the Meat Ant Iridomyrmex Purpureus (Hymenoptera: Formicidae).

Abstract

A population of the mound-building meat ant, Iridomyrmex purpureus s. s., was studied from 1971 to 1974 near the cool, wet end of its South Australian range. Seasonal variation in the numbers of nest mounds, and in number of nest entrance holes used by the population, indicate that it is under climatic stress in winter and summer. It is also subject to human interference and many mounds have been damaged; the fate of such colonies suggests that the mounds affect nest temperatures and are important in reducing winter stress. Comparison of parts of the population from areas differing in aspect and drainage shows that colony size and structure are controlled by rates of growth and survival of nests, depending largely on summer and winter stress respectively. The latter appears to be the critical factor in this population.