Economic Injury Level and Economic Threshold as required by Forest Stewardship Council for management of leaf‐cutting ants in forest plantations

Abstract

The most commonly used method to control insect pests, such as leaf-cutting ants (LCA) in forest plantations, is the application of chemical insecticides, but their use was forbidden in plantations certified by the Forest Stewardship Council because of their negative effect on the environment. 2 A 5-year derogation of their prohibition was obtained in 2016 in Argentina, on the condition that forestry companies reduce pesticide doses by 5% per year and inform the Economic Injury Level (EIL). 3 The EIL and the Economic Threshold (ET) were estimated for the first time for the Acromyrmex genus in a Salicaceae forestation. As a model, we used the damage caused by the most detrimental LCA species of Argentina (Acromyrmex lundii) in the first, most critical year of a willow plantation (Salix nigra) in the lower basin of the Paraná River. 4 The EIL (8-15 nest/ha) was useful to demonstrate the real magnitude of the damage caused by A. lundii, which justified the need for its control. The ET for profitable production (∼3 nests/ha) would not be operatively applicable in a long-term management program in our study site. This methodology could be extrapolated to other Neotropical forest plantations attacked by Acromyrmex species.

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

“…or more holes at ground level (Jiménez, 2019). Moreover, a mean density of 18.7 nests/ha of A. lundii damaged more than 60% of 70-cmhigh stakes of Nigra 4 clone, 50 days after their implantation in six experimental plots in the south of Entre Ríos province (Jiménez et al, 2021).…”

“…Nevertheless, barriers cannot be used effectively on 70-cm stakes, the most commonly used to start a plantation. In this system, stakes are buried 40 cm, leaving only 30 cm above the soil surface in which to place the barrier (Jiménez et al, 2021). This is not high enough to avoid LCA Tall stakes and guides are commonly used in the silvopastoral system (forest grazing), usually combined with apiculture, where livestock already in the second year of the plantation can graze the spontaneous vegetation growing freely around the guides/trees (Araújo et al, 2003;Casaub on et al, 2018;Montoya-Lerma et al, 2012;Pérez, 2009;Zanetti et al, 2000).…”

“…In forestry systems, Eucalyptus, Pinus, Populus and Salix plantations are the most affected by LCA (Jiménez et al, 2021;Montoya-Lerma et al, 2012;Sánchez-Restrepo et al, 2019). Damage is intense in the first years of planting, when their control can represent between 30% and 75% of the total budget dedicated to pest management (Della Lucia et al, 2014;Vilela, 1986).…”

“…LCA are considered pests because they defoliate a large number of crops of economic importance, such as coffee, cocoa, citrus, sorghum, sunflower, sugar cane, vineyards and managed forest (Anglada et al, 2013; Cantarelli et al, 2008; Cantarelli et al, 2019; Montoya‐Lerma et al, 2012; Pérez et al, 2011; Sánchez‐Restrepo et al, 2019). In forestry systems, Eucalyptus , Pinus , Populus and Salix plantations are the most affected by LCA (Jiménez et al, 2021; Montoya‐Lerma et al, 2012; Sánchez‐Restrepo et al, 2019). Damage is intense in the first years of planting, when their control can represent between 30% and 75% of the total budget dedicated to pest management (Della Lucia et al, 2014; Vilela, 1986).…”

Leaf-cutting ant (Atta laevigata Smith) in an African mahogany plantation in Minas Gerais state, Brazil

“…Leaf-cutting ants are the most important group of insects for forest crops in the Neotropical region, as they can cause intense and frequent leaf area reduction at any stage of tree development, thereby reducing growth, and often leading to its death (Zanetti et al 2014;JiméneZ et al 2020). The glass-head leaf-cutting ant can use the leaves of both monocotyledon and dicotyledon species in their foraging activity.…”