Original Article

The roles of the queen, brood, and worker castes in the colony growth dynamics of the pharaoh ant Monomorium pharaonis (Hymenoptera: Formicidae)

Tay, J.-W., Neoh, K.-B. & Lee, C.-Y.

Abstract: Known for its high reproductive rate, sociotomy, and unique nesting habits, the Pharaoh ant Monomorium pharaonis (Linnaeus, 1758) is one of the most successful tramp ant species. In this study, combinations of different caste groups were used to examine the effects of each caste on queen and worker population growth dynamics over time. The initial number of queens in an incipient colony significantly affected queen population growth and accounted for 42.2% of the overall variability over a six-month period. Queen population growth significantly decreased as the initial number of queens increased in the incipient colonies, and in most cases, each colony retained its original number of queens (eight). The brood quantity had little effect on queen population growth and was responsible for an increase of only 2.5% in the overall variability, and the worker number had no effect on queen population growth. Worker population growth was primarily affected by the initial queen number of the incipient colony, although the effects of queen, brood, and worker number on worker population growth were all significant. Overall, our results showed that the number of caste components required for colony success was much lower than expected: A mere 50 workers and one queen were sufficient for colony survival and productivity irrespective of the presence of brood.