Red Harvester Ant

Behavior

Mating is perennial and species-specific between subspecies of the red harvester ant. Males distinguish reproductive females of their species from females of other species using pheromones. This occurs as a result of sexually stimulating pheromones secreted from the poison glands of reproductive "P. barbatus" females. These pheromones are perfectly detected by males of the species upon physical contact, resulting in the stimulation of sexual behavior.

Mating occurs at reproductive aggregation sites. Secretions from the mandibular glands of males initially mark these sites. The secretions attract females, as well as additional males, resulting in strong male competition for mates. The system of mating within "P. barbatus" is comparable to lek behavior performed by many vertebrate species. The male ants congregate and collectively give off a pheromone that attracts reproductive females. The more males present to give off the pheromone, the stronger the attraction for the females. Although this practice strongly favors certain males and leaves many others without mates, the congregation of males attracts more females on the whole as opposed to pheromone release on behalf of a solitary male. Consequently, it is more desirable for the less attractive males to remain in the lek than to attempt to attract females on their own.

Reproduction

Within nonreproductive "P. barbatus" worker ants, five major tasks are performed: foraging, maintenance of the nest, defense, midden work, and convening. Roles are not constant and chemical interactions determine when certain ants engage in certain activities. As such, these tasks are relatively fluid and cannot be understood as separate processes. The transition in behavior on behalf of one group triggers behavioral transitions in other groups of worker ants.The reproductive "P. barbatus" caste is responsible for the formation of new colonies. A single queen ant establishes every colony. Large numbers of winged male ants and virgin queen ants fly to mating aggregation sites following midsummer monsoon rains. To found a successful colony, "P. barbatus" queens must mate with males from two separate lineages. One lineage results in ants that become the workers of the colony. These are the ants responsible for the nonreproductive tasks of the colony. The other lineage produces reproductive female ants. After mating with the male ants at the aggregation site, the queen flies away to establish a new colony. Upon arriving at her new nest site, the queen loses her wings and builds a nest in the soil. The entrance into the nest is then sealed off to lay her eggs in safety. With this, the colony is born. Over the course of the following six to eight weeks, the primary brood of nonreproductive worker ants emerges and begins to forage and build the colony.

Food

The main food source for red harvester ants usually consists of seeds, which they hoard in great numbers. The food is first ground to a bread-like consistency using the ants' large mandibles, and is then stored in a granary, assuring the colony access to food year-round. Seed collection on behalf of the red harvester ants benefits their ecosystem through the process of myrmecochory, in which ants aid in the dispersal of seeds while foraging for food. Both plants and ants benefit from this relationship: the plants increase their dispersal range and density, while the ants benefit from acquiring nutrients and ensuring a more secure food supply in future harvests. This is typically understood as a mutualistic interaction. Dead insects are also collected during foraging.