Drawing battlelines
a tree-dwelling African ant prunes branches of host trees to prevent stronger neighbours from invading their tree and ousting them. Crematogaster nigriceps is one of the four ant species that dwell in the Whistling Thorn Tree ( Acacia drepanolobium) in East Africa. However, competition for trees is fierce and Crematogaster nigriceps is a poor fighter. Maureen Stanton of the University of California at Davis and her colleagues have found that the ants prune branches and leaves of its host tree to prevent them from acting as bridges to neighbouring trees that house potential invaders. The ants trim branches growing towards trees with enemy colonies, leaving trees that host colonies of their own species untouched ( Nature , Vol 401, p578).