Empire of the undergrowth leaf cutter
Biotropica 39:211–215įarji-Brener AG, Chinchilla F, Umaña MN et al (2014) Branching angles reflect a tradeoff between reducing trail maintenance costs or travel distances in leaf-cutting ants. doi: 10.1016/j.anbehav.2007.07.013įarji-Brener AG, Barrantes G, Laverde O, Fierro-Calderón K, Bascopé F, López A (2007) Fallen branches as part of leaf-cutting ant trails: their role on resource discovery and on leaf transport rates in Atta cephalotes. doi: 10.1242/bio.2012703Įvison SEF, Hart AG, Jackson DE (2008) Minor workers have a major role in the maintenance of leafcutter ant pheromone trails. doi: 10.2307/3200ĭa-Silva AC, Navas CA, Ribeiro PL (2012) Dealing with water deficit in Atta ant colonies: large ants scout for water while small ants transport it. doi: 10.2307/2955Ĭherrett JM (1972) Some factors involved in the selection of vegetable substrate by Atta cephalotes (L.) (Hymenoptera: Formicidae) in tropical rain forest. doi: 10.1086/285942Ĭherrett JM (1968) The foraging behaviour of Atta cephalotes L. doi: 10.1098/rspb.2011.2583īurd M (1996) Foraging performance by Atta colombica, a leaf-cutting ant. Dissertation, Université Paul Sabatierīruce AI, Burd M (2012) Allometric scaling of foraging rate with trail dimensions in leaf-cutting ants. doi: 10.1371/journal.pone.0017667īouchebti S (2015) Comportement d’approvisionnement des fourmis coupeuses de feuilles : de la piste chimique à la piste physique. doi: 10.1006/jtbi.1993.1020īollazzi M, Roces F (2011) Information needs at the beginning of foraging: grass-cutting ants trade off load size for a faster return to the nest. This prediction offers a new perspective on the occurrence of uncleared trails in the field.Īcosta FJ, López F, Serrano JM (1993) Branching angles of ant trunk trails as an optimization cue. Contrary to previous results, we find that trail clearing is not always profitable, but profitability depends on the foraging conditions. We construct a full, scalable cost-benefit model from our own empirical measurements and literature. While this case study concludes that trail clearing is “relatively inexpensive,” we argue that it failed to include a deciding factor in the cost/benefit analysis: the cost of providing a standby clearing workforce, which is distinct from the foraging workers. No research exists on the benefits of their use, and only a single case study investigated parts of the construction costs. Construction of such trails appears costly, yet little is known about the energetics of cleared trails. Leaf-cutter ants build prominent, cleared trails of up to 200 m length through rainforest undergrowth. We explore possible mechanisms and make testable predictions for future research. This suggests that Atta colonies must have a mechanism to regulate the intensity of their trail clearing behavior. Under some conditions, however, amortization can take weeks or months, or trail clearing can become unprofitable altogether. If the patrolling workforce is not too large, the energetic savings from foraging over cleared trails offset the investment and maintenance costs within a few days. Such maintenance patrols have not previously been recognized as a cost of trail building. Profitability depends on the workforce composition, specifically, on how many ants in a traffic stream act as maintenance workforce to respond to sudden and unpredictable obstructions, such as leaf fall. Contrary to assumptions in previous work, we find that trail clearing needs not always be energetically profitable for leaf-cutting ants. We make such an account using a scalable, integrative model of trail investment and foraging energetics.
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EMPIRE OF THE UNDERGROWTH LEAF CUTTER FULL
The ecological basis of trail clearing remains uncertain, however, because no full account has been made of benefits and costs in common units that allow comparison. Workers on cleared paths move at higher speed than they do over uncleared litter, and one measurement of the time and energetic costs of trail clearance suggests that benefits of trail usage far outweigh the investment costs of trail clearing. Among those that do, leaf-cutting Atta ants build the most prominent networks, with single colonies clearing debris and obstructions from hundreds of meters of trails annually. Few ant species construct cleared trails.