Arbuscular Mycorrhizal Fungi Enhance the Insecticidal Activity of Annona muricata L. Leaves.

Annona muricata (soursop) produces secondary metabolites with antimicrobial and insecticidal properties. Arbuscular mycorrhizal fungi (AMF) are known to enhance the production of secondary metabolites in medicinal plants. In this study, we aimed to evaluate the insecticidal activity of ethanolic leaf extracts from AMF-colonized soursop trees against the fall armyworm (Spodoptera frugiperda) and the triatomine bug Triatoma pallidipennis, a vector of Chagas disease. Ethanolic leaf extracts were obtained from trees inoculated with two AMF consortia (Cerro del Metate and Agua Dulce), with the species Rhizophagus intraradices and Funneliformis mosseae, and from non-mycorrhizal plants (SM). Extracts were tested in bioassays specific to each insect, including chemical and negative controls, and survival was analyzed using Kaplan-Meier curves. Extracts from plants colonized by F. mosseae exhibited insecticidal activity against S. frugiperda, causing 72% larval mortality, comparable to that of the commercial insecticide. In contrast, extracts from plants inoculated with the Agua Dulce consortium caused 65% mortality in T. pallidipennis adults. These extracts showed significantly higher annonacin content (µg·g-1 DW). Overall, the results demonstrate that AMF colonization can enhance the synthesis of metabolites such as annonacins and contribute to increased insecticidal activity in A. muricata. Our findings suggest AMF-assisted cultivation has the potential to enhance botanical insecticides.