EFFECTS of STARVATION on NUTRIENT DISTRIBUTION IN THE PHARAOH ANT, MONOMORIUM PHARAONIS (HYMENOPTERA: FORMICIDAE) WORKERS and VARIOUS LARVAL STAGES

Abstract:
The Pharaoh ant, Monomorium pharaonis (L.) is an important pest ant species in many parts of the world. Knowledge and understanding of feeding behavior of this species are essential to the success of baiting. Transfer of a toxicant in a bait to kill a targeted colony depends on the ability of the nutrient to move within various castes and stages of a colony. Here we report the effects of nutrient distribution in workers and larvae of laboratory colonies of the Pharaoh ant. Three types of baits: 10% sucrose solution (representing carbohydrate), corn oil (representing lipid), and boiled egg yolk (representing protein) were stained with an artificial food-coloring agent and offered to colonies undergoing 1, 3, and 6 days of starvation. Larvae were divided into three stages: stage I (1 – 5 days after hatching), stage II (5 – 10 days after hatching), and stage III (10 – 15 days after hatching). The number of larvae fed by their workers at 1, 8, and 24 hours after introduction of baits were counted. Results indicated that workers actively donate carbohydrate and protein-based food to all larval stages, irrespective of their starvation period; however, oil was transferred only upon a lengthened period of starvation. Larval stage III also showed the highest percentage of individuals oil-fed by the workers. We also observed that starved colonies showed a higher number of larvae receiving food from their workers. Food was more actively transferred to the latter two stages when compared to the youngest one. The function of each nutrient for colony development, role of larval stages as storage and digestion component of an ant colony, and the implication of our findings towards baiting strategies for Pharaoh ant control are discussed.