Context-dependent influence of path integration on nest plume following in desert ants.

The desert ant Cataglyphis fortis forages individually for dead arthropods in the Tunisian saltpans. Homing ants return to their nest by following a path integration (PI) derived home vector and finally pinpoint the nest entrance by tracking the nest's carbon dioxide plume. However, as long as PI tells the homing ant that it has not reached its nest's vicinity yet, plume following is inhibited. This avoids an ant entering foreign nests en route. If homing ants cannot find their nest, they begin a systematic search that results in the formation of a search-derived PI vector pointing toward the nest's location. Here, we show that foraging-derived but not search-derived PI vectors inhibit plume following. Interestingly, although searching ants experience increased heat stress, heat stress alone cannot explain the observed effects. We conclude that PI vectors can inhibit plume following in homing but not in nest-searching ants.