Hydrocarbons on Harvester Ant (Pogonomyrmex barbatus) Middens Guide Foragers to the Nest

Abstract

Colony-specific cuticular hydrocarbons are used by social insects in nestmate recognition. Here, we showed that hydrocarbons found on the mound of Pogonomyrmex barbatus nests facilitate the return of foragers to the nest. Colony-specific hydrocarbons, which ants use to distinguish nestmates from non-nestmates, are found on the midden pebbles placed on the nest mound. Midden hydrocarbons occur in a concentration gradient, growing stronger near the nest entrance, which is in the center of a 1-2 m diameter nest mound. Foraging behavior was disrupted when the gradient of hydrocarbons was altered experimentally. When midden material was diluted with artificial pebbles lacking the colony-specific hydrocarbons, the speed of returning foragers decreased significantly. The chemical environment of the nest mound contributes to the regulation of foraging behavior in harvester ants.

Interactions with Combined Chemical Cues Inform Harvester Ant Foragers' Decisions to Leave the Nest in Search of Food

“…First, foragers require a rapid rate of return of patrollers [16], about 1 per 10 sec, to leave the nest for the first time in the morning, indicating there is a short window during which foragers react to encounters with returning ants. Second, foraging activity responds very quickly, within minutes, in response to a change in forager return rate [23]–[24]; [35]–[36].…”

Analysis of Insect Cuticular Compounds by Non-lethal Solid Phase Micro Extraction with Styrene-Divinylbenzene Copolymers

“…In some cases, SPME fibers can be saturated by a disproportionate concentration of one or more compounds from a specific body segment (Ferreira-Caliman, personal observation), but we did not observe such saturation with the Chromosorb®. Furthermore, it may be possible to mix Chromosorb® with nest materials in experiments on orientation of ants (Sturgis et al, 2011) or in analyses of bee comb waxes (stingless bees: Pianaro et al, 2007;honeybees: D'Ettorre et al, 2006).…”

The Sensory Ecology of Ant Navigation: From Natural Environments to Neural Mechanisms

“…Cuticular hydrocarbons [i.e., molecules that are usually responsible for nestmate recognition in hymenopterans (9)] were found to occur in a concentration gradient surrounding the nest entrance. An experiment in which the natural gradient was changed resulted in decreased homing speeds, suggesting that homing ants use this gradient (102). In consideration of both results, it seems reasonable that ants generally use whatever olfactory cue helps pinpoint the nest.…”

“…Indeed, displaced homing ants exposed to an artificial CO 2 plume will follow it as though it originated from a real nest (14). Another study found that P. barbatus pinpoints the nest by following olfactory cues (102). Cuticular hydrocarbons [i.e., molecules that are usually responsible for nestmate recognition in hymenopterans (9)] were found to occur in a concentration gradient surrounding the nest entrance.…”