Leaf-cutting ants in commercial forest plantations of Brazil: biological aspects and control methods

Abstract

Forest plantations represent the fourth largest crop by planted area in Brazil. However, leaf-cutting ants can compromise their establishment and development. Atta and Acromyrmex (Hymenoptera: Formicidae) ant genera are the main pests in Eucalyptus and Pinus plantations, and their management is fundamental to maintain the forestry sector. Here, we describe biological aspects of leaf-cutting ants in Brazilian commercial forest plantations and the feasibility of different methods to control these insects. Physical and biological control methods are not effective in suppressing leaf-cutting ants nests of any size. Chemical control is the most used method and is based mainly on ant baits with high efficiency, easy application, and low operational cost. Ant baits comprise a carrier, usually citrus pulp, and an active ingredient. Dodecachlor was the first active ingredient used on a large scale in ant baits in Brazil. The use of this chemical was suspended because of its toxicity and persistence and replaced by sulfluramid, which is currently the most used active ingredient in ant baits. Although this compound controls leaf-cutting ants effectively, the raw material used in the manufacture of sulfluramid (perfluorooctane sulfonyl fluoride) was listed at the Stockholm Convention in 2009 as a persistent organic pollutant. Diverse alternative control methods have been tested without success and for this reason, sulfluramid is still used to control leaf-cutting ants. Regardless of the effectiveness of sulfluramid-based baits, researchers should put more effort into developing control methods safer to the environment.