Comparative effect of the venoms of ants of the genus Pachycondyla (Hymenoptera : Ponerinae)

The venoms of 12 Pachycondyla ant species, ail generalist predators, were c ompared for their paralytic and lethal effects during prey capture of the c ricket. Acheta domesticus. The observed values covered a wide range that se ems surprising when considering the close phylogenetic relatedness of the s pecies. Although employed for different purposes, these venoms had the same type of physiological effect. They caused a rapid, dose-dependent and reve rsible paralysis, followed by a second slow-acting paralysis which was perm anent when complete and led to death in less than 4 days. This finding sugg ests the existence of similar toxins and of both neurotoxins and histolytic compounds as necrosis were often observed in dead animals. Comparisons bas ed on the nesting habitats of the species highlighted significant differenc es in paralysis after 2 h and lethality with arboreal species' venoms more efficacious than those of ground-dwelling species, thanks to their higher p otency and their rather fast-acting effect. Such a tendency may be consider ed as an adaptation to arboreal life as the possibilities of escape for the prey are more numerous than on the ground or in the leaf litter. (C) 2000 Elsevier Science Ltd. All rights reserved.