The best of heavy queens: influence of post-flight weight on queens’ survival and productivity in Acromyrmex subterraneus (Forel, 1893) (Hymenoptera: Formicidae)

Abstract

The weight of post-flight ant queens reflects how much stored resources are available to overpass the new colony foundation phase. Acromyrmex queens must dig the nest and forage during this period to cultivate the symbiotic fungus for larvae feeding, implying even higher energetic costs. But if the activities of foraging and excavating were excluded from this phase, would it be possible to mitigate the effect of the queen’s post-flight weight on its survival and productivity? In this context, we tracked the survival of 1128 queens already classified into Featherweight, Lightweight, Welterweight and Heavyweight until the emergence of the first workers. Also, for 476 queens we registered the productivity, the proportion of queens that regurgitated the symbiotic fungus, of those that transported it to leaf surface, as well as the proportion that presented some pathogenic fungus on their body surface after death. After the 2nd week, 45% of queens had died and the post-flight weight influenced survival chances, with featherweight queens presenting the highest mortality rate but not the lowest productivity. Here we add the queen’s post-flight weight, the absence of symbiotic fungus and, less remarkably, the contamination by pathogenic fungus as other variables that should likewise be considered as factors that reduce the success rate of colony foundation. We highlight that the post-flight weight did not influence the productivity, so when the queen survives, the offspring production is not affected, giving queens of different weights the same chance to become successful at colony foundation.