Long‐term quantification of leaf‐cutting ant damage in willow forestations in the lower delta of the Paraná River, Argentina

Abstract

Leaf‐cutting ants are major pests of Neotropics forest plantations. The lower delta of the Paraná River contains the main Argentine Salicaceae production, strongly attacked by Acromyrmex lundii and Acromyrmex ambiguus. Nevertheless, there is no damage quantification in willow plantations attributed to leaf‐cutting ant species. In an area without leaf‐cutting ant control, we installed 15 blocks with eight willow stakes each: four clones × two treatments; with and without leaf‐cutting ant exclusion. We used two traditional (Americano, Nigra 4) and two new (Géminis, Yaguareté) commercial clones. During 2014–2018, we measured the damaged foliage, height and diameter of each tree. Foliage was damaged intensely during the first 2 years. After 1537 days, the loss in height and diameter was greater in Americano (70%), followed by Géminis (50%–60%), Yaguareté (40%–50%) and Nigra 4 (45%–40%). Stake survival with exclusion was greater (>80%) than stakes without exclusion (<50%). Total loss of wood volume was 93% for Americano, followed by Géminis (77%), Yaguareté (66%) and Nigra 4 (51%). Although the new clones were heavily attacked, they produced two to three times more wood volume than Americano; replacing Americano with the new clones would help to reduce leaf‐cutting ants impact on plantations and pesticides released into the environment.

Landscape configuration modulates the presence of leaf-cutting ants in eucalypt plantations

“…The impact of LCAs on forestry is unquestionable (Montoya-Lerma et al 2012). For example, damage quanti cations carried out on plantation forests of pines (Buratto et al 2012;Cantarelli et al 2019;Nuñez et al 2020;Scherf et al 2022), eucalypts (Zanetti et al 2003;Souza et al 2011) and willows (Jiménez et al 2021(Jiménez et al , 2022 in the Southern Cone of America have shown that LCAs generate signi cant losses (i.e. by reduce tree growth or survival rates) and that, in some cases, they can severely compromise economic viability.…”