Bioactivity of ethanolic and hexanic extracts of Annona montana Macfad. in the control of Aphis craccivora Koch (Hemiptera: Aphididae)

Abstract

The use of synthetic insecticides to control pests in agriculture may negatively affect the environment, human health, and contribute to the emergence of resistant pest populations. This study aimed to investigate the chemical composition and evaluate the bioactivity of ethanolic leaf extracts and hexanic seed extracts of Annona montana Macfad. against Aphis craccivora Koch. Bioassays were conducted to assess toxicity, feeding repellency and translaminar activity. For the chemical characterization of the hexanic seed extract, 97.2 % of the constituents were identified, with the linoleic (37 %), oleic (36.7 %), palmitic (16.9 %) and stearic (5.2 %) acids as the major compounds. For the ethanolic leaf extract, 83.31 % of the constituents were identified, mainly α-tocopherol (19.97 %), β-sitosterol (10.16 %), cyclohexanecarboxylic acid, heptadecyl ester (6.26 %), methyl linolenate (5.35 %) and phytol (4.43 %). Both extracts showed toxic effects on A. craccivora, with the ethanolic extract exhibiting a higher toxicity against nymphs and adults of the cowpea aphid. Repellent and translaminar effects were also observed, with the hexanic seed extract showing a more pronounced activity in both cases.

KEYWORDS: Bioinsecticide, cowpea aphid, insecticide plant.