Foraging for the fungus: why do Acromyrmex subterraneus (Formicidae) queens need to forage during the nest foundation phase?

Abstract

1. Semiclaustral ant queens must pay the price of foraging to guarantee their survival and also that of their brood through the nest foundation phase. For leaf-cutting ant species, the challenge is even greater, as they also need to cultivate their symbiont fungus.2. We hypothesised that suppressing foraging activity could reflect in larger offspring and higher survival, as queens would be entirely dedicated to rearing the brood and initial fungus.3. By providing easy access to leaves or completely denying it, we evaluated how foraging runs interfere in Acromyrmex subterraneus queens' survival, productivity, and variation of body mass components.4. Three foraging conditions were simulated: Starved -no leaves, Spoiled -leaves inside the nest chamber, and Walker -leaves 3 m away from the nest chamber. We registered the number of dead queens, offspring, weight of the fungus garden, fresh and lean dry mass of the queens, as well as their lipid and water contents.5. Survival of Starved queens, which did not oviposit, was lower than that of Spoiled and Walker queens, although weight loss, water content, and lean dry mass were similar. While lipid content reduction was similar for Spoiled and Walker queens, the former had more larvae and pupae, and a heavier fungus garden than the latter, suggesting a greater rearing effort of Spoiled queens toward them both.6. The simulated foraging conditions provided novel data for a semiclaustral leaf-cutting ant species that evidences that fungus garden cultivation is definitively the main driving force for the colony founding success.

Life history, nest longevity, sex ratio, and nest architecture of the fungus-growing ant Mycetosoritis hartmanni (Formicidae: Attina)

“…We found no large larvae or pupae in the incipient garden, but small brood may have been present hidden in the garden matrix. The observation of foraging behavior by a foundress queen suggests semi-claustral nest founding, as occurs in other fungus-farming ant genera but not in the genus Atta [ 16 , 18 , 49 – 51 ].…”

Study on leaf-cutting ants: from laboratory maintenance to applied personality studies with behavioral and molecular approaches

“…These leaf-cutting ants are also considered agricultural pests in particular regions of America, and have recently attracted more interest in early stages colony development 33 and toxic baits interaction 34 focused research. Although this work focuses on leaf-cutting ants, especially for highlighting fungus garden care, the maintenance protocol and the different types of nests described are also applicable to other groups of ants.…”