Sex differences in cooperative silk-spinning by weaver ant larvae.

Final-instar larvae of weaver ants (Oecophylla longinoda) use their silk for nest construction rather than for cocoon spinning; this commitment represents a shift from entirely selfish to entirely cooperative behavior that occurred after the emergence of the phylogenetically advanced subfamily Formicinae. Male larvae were found to have smaller silk glands and to contribute substantially less silk to nest construction. The hypothesis of kin selection appears to be the most plausible and parsimonious explanation of this sex difference, but other, individual-level modes of selection have not been eliminated.