Insecticidal activity and phytochemical profiling of Annona squamosa (L.) leaf extract against the fall armyworm, Spodoptera frugiperda (J.E. Smith)

To identify an effective botanical extract for pest control, six locally available plant species were screened for their toxic effects against Spodoptera frugiperda (J.E. Smith) larvae. These species included Annona squamosa (L.), Calotropis gigantea (L.) W.T. Aiton, Carica papaya (L.), Datura metel (L.), Ricinus communis (L.) and Rottboellia cochinchinensis (Lour.) Clayton. Among these, A. squamosa demonstrated the highest larval mortality at both 5% and 10% concentrations. Based on these promising results, subsequent bioassays were conducted using a range of concentrations (4%, 6%, 8%, 10%, 12%, 14% and 16%) of A. squamosa to evaluate its larvicidal, antifeedant and ovicidal activities. The median lethal concentration (LC50) for second instar larvae, observed 72 hours after treatment (HAT), was determined to be 8.65% (w/v). The antifeedant assay revealed a dose-dependent response, with 99.38% antifeedancy at the highest concentration tested (16%). Moreover, A. squamosa exhibited 100% ovicidal activity across all concentrations. Gas Chromatography-Mass Spectrometry (GC-MS) analysis of the extract identified 39 compounds, with 16-hentriacontanone, neophytadiene, caryophyllene and phytol showing the most significant peak areas. These findings suggest that A. squamosa leaf extract possesses substantial larvicidal, antifeedant and ovicidal properties against S. frugiperda, highlighting its potential as an eco-friendly, non-toxic alternative to synthetic insecticides. This botanical extract may offer valuable contributions to integrated pest management (IPM) strategies, promoting sustainable agricultural practices.