Biomass consumption, foraging activity and harvesting patterns in two sympatric leaf‐cutting ant species in a Salicaceae plantation in Argentina

Leaf‐cutting ants (LCA) are one of the most important pests in the Neotropics region. To estimate the potential biomass consumption by LCA on Salicaceae plantations in the lower delta of the Paraná River, we studied the foraging activity and harvesting patterns of Acromyrmex lundii (Guérin‐Méneville, 1838) and Acromyrmex ambiguus (Emery, 1888) (Hymenoptera: Formicidae) in a 14‐year‐old poplar plantation in Argentina. Foraging activity (workers/time), harvested vegetal biomass (dry weight/time) and climatic conditions (temperature and relative humidity) were monitored daily and seasonally in nests from autumn 2016 to summer 2017. The two sympatric species harvested a similar quantity of dry biomass throughout the year (4.9–6.0 kg/colony). Although both species were active in all seasons, their foraging activity was higher in spring and summer, but they avoided extreme temperatures. The accumulated biomass harvested for both species was higher in summer (28.8 and 25.7 g/colony/day, for Ac. ambiguus and Ac. lundii , respectively). However, Ac. lundii harvested three times more biomass than Ac. ambiguus in spring (30.3 and 13.1 g/colony/day, respectively). Although the highest consumption on the vegetation occurred in summer, control tasks should be started during spring (sprouting phase), the most vulnerable period for Salicaceaes. The consumption of new leaves in spring is critical for tree growth, survival and wood production, especially by Ac. lundii , the most detrimental species during this season.