Forage communication, nest moving recruitment, and prey specialization in the oriental ponerine Leptogenys chinensis

Summary

In North Central Sri Lanka the ant Leptogenys chinensis specialises in feeding on fungus-growing Macrotermitinae (Odontotermes, Hypotermes), which are the commonest termites in this area. They are captured at their feeding sites. The ants recognize the termites by the scent that they emit. Workers and sexuals are the preferred prey. Termites of other taxa (Nasutitermitinae, Rhinotermitidae) are sometimes accepted and sometimes rejected. Refusal and acceptance are not correlated with the systematic position of the termites. Usually the nests of L. chinensis comprise 200–300 workers. Externally the female ergatoids do not differ from the workers. The ants live in naturally available cavities and move nests frequently. We investigated the communication of this species in relation to foraging and nest-moving. While foraging, single workers lay a light and nest-moving. While foraging, single workers lay a light exploration trail with venom. Successful scouts return to the nest and perform recruiting runs. Experiments with various blocked pheromone glands and decoys showed that the secretions of the poison gland and the Janet gland have to be applied to the ground. By this means groups of workers are recruited and led to a feeding place by a scout. When the scout was removed such groups would still, although slightly disturbed, find their way to the prey. Workers running alone are also observed. The secretion of the Janet gland has a recruiting effect, whereas the venom consists of two compounds: a compound of low volatility responsible for orientation, and a highly volatile compound which we interpret as being a way of estimating the age of the trail. In most cases, the recruited workers return singly to the nest. Retrieval of prey in groups is primarily observed with captured termite sexuals. Males use the trails to find and enter alien nests.

In addition to the three chemical signals, stridulation with the gastral stridulatory organ is used as a mechanical signal in the frequent event of nest-moving. This induces general stridulation in the nest and initiates nest-moving, which is accomplished within a few minutes.