Passera et al. (1996) have shown that intraspecific competition may affect the ratio of castes among social insects. Colonies of the ant Pheidole pallidula increase their relative investment in soldiers when exposed to other colonies of the same species. The worker force is divided into two basic castes: small-headed minors (workers) who do most of the labor, and large-headed majors (soldiers) specialized for defense. In a laboratory experiment, when colonies were exposed to odors from a conspecific colony, they increased the number of soldier pupae. After seven weeks, those colonies exposed to conspecific odors averaged 40.1 soldiers as compared with an average of 22.6 soldiers in the control colonies.
Was this article helpful?