Essential oil of garlic, Allium sativum L.: A promising alternative for the management of Sitophilus oryzae (L.)

The study evaluates the effectiveness of garlic essential oil as a fumigant and contact toxicant against adult rice weevils (Sitophilus oryzae L.) (Curculionidae: Coleoptera). Garlic essential oil demonstrated significant fumigant toxicity, causing 56.67% adult mortality at a concentration of 3 µl/96 cm³ air on the first day, which increased to 99.13% by the fifth day after treatment (DAT). In addition, garlic essential oil exhibited contact toxicity, achieving up to 100% mortality at doses of 4 and 5 µl/40 g seeds. Even at lower concentrations (1 µl), mortality rates were as high as 78.33%. The calculated LC50 value was 2.58 µl/40 g of seeds. Garlic essential oil also had a considerable effect on reproduction, as no adults emergence was observed from seeds treated with 4 µl/40 g. GC-EAD analysis identified 39 compounds in garlic essential oil, with male and female S. oryzae exhibiting different antennal responses. Females displayed stronger reactions to alcohols and esters, while males were more responsive to alkenes and alkanes. The presence of chemical constituents in garlic essential oil that influence insect behaviour underscores its potential as a viable pest management solution against stored-product pests and identified a set of compounds responsible for its insecticidal toxicity. Further exploration of these compounds for their insecticidal properties using GC-EAD studies and their development into the formulations could provide significant benefits to farmers and contribute to sustainable pest management practices.