Predation efficiency of two Patagonian Dorymyrmex ant species varying in forager numbers

LESCANO, N.; WERENKRAUT, V.; ELIZALDE, L.; PIRK, G. I.

VIRTUAL

Simposio; Primer Simposion Iberoamericano de Mirmecología; 2020

Predation efficiency of two Patagonian Dorymyrmex ant species varying in forager numbersElizalde L., Lescano M.N., Werenkraut V. Pirk G.I.LIHo, Laboratorio Ecotono, INIBIOMA-CONICETPredation is an important force structuring communities. Although it is generally accepted that the larger the predator group the more efficient at exploiting abundant resources, some empirical evidence contradicts this idea. We explored the association between number of foragers and predation efficiency in two generalist ant species that differ in their forager numbers. We conducted a field experiment of increasing lepidopteran larvae density around nests of two abundant Dorymyrmex ant species in semiarid Patagonia: D. tener and D. antarticus, where D. tener presents higher forager numbers (mean forager number before recruitment in a trail was 8.6 and 1.7 ants/min, respectively). We (1) compared the effectiveness (ability to complete a task) and efficiency (speed of task performance) in the predation process between species, and (2) studied how they responded to increasing prey densities, by sequentially adding 3, 6 and 12 larvae in the same arena. Although D. tener discovered similar number of arenas than D. antarticus, it was more effective as it recruited more foragers and removed more larvae. This species was more efficient than D. antarticus in all predation subtasks, and the time used to remove one larva depended on the number of larvae in the arena, being faster for the 12-larvae treatment and lower for the 3-larvae treatment. Thus, predator group size (number of foragers) is key for predation efficacy and efficiency, but other traits related to individual abilities of workers, such as walking speed and ability to catch preys, might also be important.