ORIGIN OF OLEIC-ACID, CORPSE RECOGNITION SIGNAL IN THE ANT, FORMICA-JAPONICA MOTSCHLSKY (HYMENOPTERA, FORMICIDAE)

Oleic acid levels on the body surface of ant corpses of Formica japoni ca increase 48 h after death. Live workers also carry the ant corpses 48 h after death. In contrast, triglycerides in the hemolymph decrease drastically during the 48 h after death. The constituent fatty acids of the triglycerides are linoleic acid, oleic acid, stearic acid, palm itoleic acid, and palmitic acid, which are also found in the free fatt y acids in the hemolymph of the ant corpse. The mass spectrum suggests that the major compounds of the triglycerides are triolein and dioley lpalmitin. Large amounts of the oleic acid are stored in the triglycer ides. When a worker ant was irradiated with microwaves soon after deat h, the free fatty acids on the cuticle did not increase much and the t riglycerides in the hemolymph did not decrease. However, the amount of triglycerides on the cuticle was more than that on a corpse that was not irradiated. These results suggest that the oleic acid serves as a corose recognition signal and is generated by enzymatic hydrolysis of triglyceride, with the enzyme activated after death.