Brood arrangement and food distribution among larvae under different colony conditions in the pharaoh's ant, Monomorium pharaonis (Hymenoptera: Formicidae)

The Pharaoh's ant, Monomorium pharaonis (L.) is one of the most widely distributed and most successful tramp species in the Formicidae family. It is an important pest ant in many parts of the world. Therefore, it is essential to understand the feeding behavior of this species to further enhance the efficiency of baiting. In the first part of this study, we observed the trend in brood arrangement in an ant colony. This was accomplished by feeding them with dried tuna fish stained with blue food dye. 10 colonies consisting of 0.3 g of mixed-stages brood, 4 queens and 300-400 workers were set up. Digital still photographs were taken 1 day after they were given dyed tuna. The arrangement of brood in each colony was observed and discussed. In the second part of our study, we simulated 8 different colony conditions to observe the trend in food distribution among two larval stages (Instar 2 and 3). The two major groups were colonies with old larvae and colonies with mixed-stages of brood. These were further separated into queenless/queenright colonies and fed/unfed colonies. Each condition was replicated five times. Dried tuna fish (stained with blue food dye) was used to determine the number of larvae that were fed with it. Digital still photographs were taken at different time intervals (2H, 4H, 8H, 24H, & 72H). They were later used in counting the number of larvae fed by the workers. Data were subjected to one-way ANOVA followed by Tukey HSD (P < 0.05). Results indicated that both instars' feeding in all the colonies differed from one another only after 24 hours. The differences in all eight conditions are discussed.