Preliminary Evaluation of the Toxic Effects of Essential Oils as Natural Pesticides Against Maize Weevil (Sitophilus zeamais) and Its Fungal Pathogens

To control maize weevils (<i>Sitophilus zeamais</i>), a major pest of stored grains, this study explores the use of essential oils from <i>Eucalyptus globulus</i> and <i>Lantana camara</i> as natural biopesticides. Given the risks of synthetic pesticides, these oils offer a sustainable alternative. The research first identified ten fungal pathogens associated with the weevils, including the dominant species, <i>Fusarium solani</i>. Preliminary results showed that both oils were then tested for their ability to kill the fungi and the weevils. <i>Eucalyptus globulus</i> oil proved to be a superior antifungal agent, inhibiting fungal growth by up to 93%, significantly outperforming <i>Lantana camara</i> oil. Both oils demonstrated potent insecticidal properties, achieving 100% weevil mortality at a 10% concentration within 24 hrs. However, <i>Eucalyptus</i> oil was more effective, maintaining 100% mortality even at a lower 5% concentration, unlike <i>Lantana</i> oil. Chemical analysis showed that <i>Eucalyptus</i> oil's high effectiveness may be associated with its main component, eucalyptol (52.8%). <i>Lantana</i> oil had a more varied composition, with caryophyllene (31%) as its primary constituent. The findings suggest that <i>Eucalyptus globulus</i> essential oil is a promising, two-in-one biopesticide capable of controlling both maize weevils and their associated fungal pathogens.