Source of the Post-Pharyngeal Gland Contents in the Red Imported Fire Ant, Solenopsis invicta12

Abstract

The lumina of the post-pharyngeal glands of all castes of the red imported fire ant, Solenopsis invicta Buren, appeared empty at the time of emergence. After 7 days exposure of newly emerged ants to sugar water, the gland lumina remained empty even though the crop was filled with sugar water. Only foods containing lipids caused the lumina to enlarge and acquire the characteristic yellow color typical of glands from older workers and reproductives. The post-pharyngeal glands selectively acquired lipids from ingested foods and the lipids remained in the gland lumina for long periods of time. The post-pharyngeal glands of queens did not sequester radiolabeled triglycerides or fatty acids injected into the haemolymph. The results suggest that these 2 major lipid components of the post-pharyngeal glands are acquired from the food of the adult ant.