TRAIL COMMUNICATION IN THE ANT MEGAPONERA FOETENS (FABR) (FORMICIDAE,PONERINAE)

The African ponerine ant Megaponera foetens conducts well organized gr oup raids on termites. Observations of raids in western Africa, togeth er with laboratory experiments, confirm previous reports that recruitm ent is based on a scout system and trail pheromones. One component of the trail signal derives from the poison gland. We discovered a second trail pheromone which originates from the pygidial gland. The latter secretions have a more powerful recruitment effect whereas poison glan d secretions contain a much longer-lasting orientation cue. The secret ions of the sternal gland, Dufour's gland and hind gut contents do not elicit trait-following. The long bristles surrounding the tip of the gaster are innervated and probably serve as mechano-receptors during t rail-laying. No evidence could be found that the conspicuous stridulat ory sounds produced by the ant columns serve intraspecific communicati on. In the field, stridulation by raiding ants was observed exclusivel y as a response to disturbance. In the laboratory, strong vibrations o f the ground as well as air currents elicit stridulation. Air/CO2 mixt ures are significantly more efficient in releasing stridulation compar ed to pure air. We suggest that these sounds are aposematic warning si gnals aimed at potential vertebrate predators,