Toxicity of Hydramethylnon to Leaf-cutting Ant Atta sexdens rubropilosa Forel (Hymenoptera: Formicidae)

Since 2009, when sulfluramid was listed in annex B of the Stockholm Convention’s Persistent Organic Pollutants, effort has been made to search for other active ingredients to use in baits for controlling leaf-cutting ants in Brazil. Considering that active ingredients that inhibit insect cellular respiration have been shown to be effective in controlling ants, the current work aimed at assessing the toxicity of hydramethylnon to Atta sexdens rubropilosa workers. Hydramethylnon was dissolved in acetone and in a solution of acetone + soy oil then incorporated in artificial diet at concentrations of 1 µg/mL, 5 µg/mL, 10 µg/mL, 100 µg/mL, 200 µg/mL and 1000 µg/mL. The treatments where ants were daily fed on the diet containing hydramethylnon at 100 µg/mL, 200 µg/mL and 1000 µg/mL, especially those dissolved in soy oil, exhibited high mortality in comparison to the controls. The data presented here confirms the insecticidal activity of hydramethylnon and highlights the importance of employing soy oil in the formulation of baits to control leaf-cutting ants because it enhances hydramethylnon efficiency.