Bioactivity of plant extracts against Atta sexdens (Hymenoptera: Formicidae) workers by ingestion

Abstract

The leaf-cutting ant Atta sexdens stands out as a pest of several crops of economic importance. The main control method for this species is the application of ant baits. However, one of the most used active ingredients in the ant baits, sulfluramid, was classified as an organic pollutant, highlighting the urgent need to seek new active ingredients with greater ecological and environmental safety. The present goal is to evaluate the bioactivity of botanical extracts in workers of the leaf-cutting ant A. sexdens by ingestion, aiming to select extracts with essential characteristics for use in toxic baits for the subsequent isolation of substances and prospection of insecticides. Insect survival in the first evaluation (24 h) was high in all treatments with extracts. Survival time varied between treatments, with mortality reaching maximum values between 10 and 20 days for most of the treatments. At 21 days, live ants were observed only in treatments T3 (M. maracasana-stem) and T4 (C. mastigophorus-bark), with survival of 10% and 3.3%, respectively, not significantly differing between them. The extracts of Metrodorea maracasana, Conchocarpus mastigophorus, Erythoxylum macrocalyx, and Erythoxylum plowmanii showed insecticidal activity against A. sexdens workers. The insecticidal activity of the species Erythoxylum macrocalyx, E. plowmanii, Metrodorea maracasana, and Conchocarpus mastigophorus against A. sexdens workers is shown for the first time. The studied extracts have potential for the fractionation and selection of substances responsible for insecticidal activity, allowing for the prospection of toxic baits.