1Department of Zoology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat Aviv 69978, Israel.
2LEEC, University of Paris 13, Villetaneuse, France.
Worker cuticular chemistry of Pachycondyla apicalis constitutes a blend of hydrocarbons including alkanes, alkenes, and alkadienes, with 9-heptacosene and 5,9-heptacosadiene as the major products. There is a large congruency between PPG and cuticular hydrocarbons. These ants have a well-developed cuticular brush the front legs that they frequently pass through the bucal cavity while grooming. Since these brushes have higher amounts of hydrocarbons than either the middle or hind legs, we hypothesized that they are involved in hydrocarbon circulation. When the front legs of workers were restrained for 24 hrs to prevent contact with the bucal cavity, the amount of hydrocarbons in the PPG decreased considerably with a parallel increase in the brushes. If the ants are kept alive for an additional 24 hrs after their legs were freed, hydrocarbon amounts both in the PPG and the front legs returned to normal. Similar results were obtained with ants that had their mouth blocked. Analyses of crop content revealed the same hydrocarbons profile as in the PPG, but there were no differences in amounts between the treatment and the control. We assume that part of the PPG hydrocarbons are cleared via the alimentary canal. Grooming behavior of restrained then freed ants was followed for four days. There was a significant increase in total grooming during the first three days that declined in the fourth day. Especially intensive were grooming involving the front legs - mouth, and front legs - antennae. Grooming involving the hind legs - body were not different between the control and the treatment. We conclude that the front leg brush is a site of hydrocarbon accumulation and that the PPG is charged frequently during selfgrooming.