Chemical control of Acromyrmex lundi (Hymenoptera: Formicidae) in anthropic ecosystems

Abstract

Background: Leaf-cutting ants are pests in agriculture, forests and pasture and, usually, controlled with toxic baits. The management and control of leaf-cutting ants is complex as a consequence of its sociability and behavior. We tested three toxic baits with abamectin, fipronil and sulfluramid to control colonies of Acromyrmex lundi Mayr, 1865 (Hymenoptera: Formicidae), in two seasons: ‘Spring 2020’ and ‘Summer 2020/21’, in Argentina. Results: The percentage of effective bait carried in the spring was similar between treatments with 80%, 80% and 90% for those with abamectin, fipronil and sulfluramid. The ant flow of A. lundi decreased after toxic bait applications compared to the control through time in all treatments. This activity was higher in the spring than in the summer. The baits reduced the foraging activity of A. lundi from 5 to 96 days after application (DAA). Abamectin and fipronil baits controlled 50% and 67% of the nests in the spring, and 20% and 43% at 96 DAA in the summer. Sulfluramid was the best treatment, killing 90% of A. lundi nests. Conclusion: The baits decrease the foraging activity of A. lundi until 96 DAA, with total or partial death of its colonies varying between treatments. The ant symptoms with the sulfluramid bait appeared faster than with fipronil and may be a result of the low level of carry-over or differences in the chemical quality of the active ingredients.