LESCANO Maria natalia
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The more the better? Predation efficiency of two Patagonian Dorymyrmex ant species varying in forager numbers
ELIZALDE, L.; LESCANO M.N; WERENKRAUT, V.; PIRK, G.
Simposio; I Simposio Iberoamericano de Mirmecología; 2020
Predation is an important force structuring communities. Although it isgenerally accepted that the larger the predator group the more efficient atexploiting abundant resources, some empirical evidence contradicts this idea. Weexplored the association between number of foragers and predation efficiency intwo generalist ant species that differ in their forager numbers. We conducted afield experiment of increasing lepidopteran larvae density around nests of twoabundant Dorymyrmex ant species insemiarid 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 betweenspecies, and (2) studied how they responded to increasing prey densities, by sequentiallyadding 3, 6 and 12 larvae in the same arena. Although D. tener discovered similar number of arenas than D. antarticus, it was more effective asit recruited more foragers and removed more larvae. This species was moreefficient than D. antarticus in all predationsubtasks, and the time used to remove one larva depended on the number oflarvae in the arena, being faster for the 12-larvae treatment and lower for the3-larvae treatment. Thus, predator group size (number of foragers) is key forpredation efficacy and efficiency, but other traits related to individualabilities of workers, such as walking speed and ability to catch preys, mightalso be important.