Natural arsenal of <i>Magnolia</i> sarcotesta: insecticidal activity against the leaf-cutting ant <i>Atta mexicana</i> (Hymenoptera: Formicidae)

Abstract Atta mexicana (F. Smith) (Hymenoptera: Formicidae) is a significant agricultural pest in Mexico. This study tested the insecticidal activity of ethanol extracts from the sarcotesta of three Magnolia (Magnoliaceae) species endemic to Mexico against A. mexicana . Contact and ingestion bioassays were performed using various ethanol extract concentrations. After 72 h of exposure, Magnolia pugana (Iltis &amp; A.Vazquez) A.Vazquez &amp; Carvajal showed the highest contact toxicity at 2.0 mg/mL, 0.2 mg/mL, and 0.02 mg/mL, with a lethal concentration to 90 % mortality (LC 90 ) of 0.02 mg/mL. Magnolia perezfarrerae A.Vázquez &amp; Gómez-Domínguez exhibited toxicity at 2.0 mg/mL and 0.2 mg/mL, with LC 90 = 0.1 mg/mL, while Magnolia vovidesii A.Vázquez, Domínguez-Yescas &amp; L.Carvajal showed toxicity at 4.0 mg/mL and 0.04 mg/mL, with LC 90 = 0.4 mg/mL. The ethanol extracts also demonstrated significant toxicity by ingestion. The most effective concentrations for M. pugana was 2.0 mg/mL with LC 90 = 0.24 mg/mL, while for M. perezfarrerae , they were 2.0 mg/mL, 0.2 mg/mL, and 0.02 mg/mL (LC 90 = 0.06 mg/mL). For M. vovidesii , the most effective concentrations were 4.0 mg/mL, 0.4 mg/mL, and 0.04 mg/mL (LC 90 = 0.07 mg/mL). Chemical analysis revealed the presence of alkaloids, terpenes, and phenols in the extracts. This study suggests that the tested Magnolia sarcotesta extracts have great potential as effective botanical pesticides against A. mexicana , implying promising insights for developing agricultural pest management strategies.