Evaluation of Medicinal Plant Extracts as Safe Alternatives to Chemical Insecticides for Enhancing Food Safety and Public Health

Introduction and purpose: Chemical insecticides, such as aluminum phosphide, pose significant health, environmental, and food safety challenges. To reduce reliance on these harmful compounds and promote sustainable alternatives, this study evaluated the efficacy of medicinal plant extracts as eco-friendly substitutes for stored-product pest control. In total, four medicinal plants, namely Tobacco, Eucalyptus, Wormwood, and Asafoetida, known for their antimicrobial properties in Iranian traditional medicine, were investigated in this study. Methods: Hydroalcoholic extracts of Tobacco (Nicotiana tabacum L.), Eucalyptus (Eucalyptus globulus Labill.), Asafoetida (Ferula assa-foetida L.), and Wormwood (Artemisia absinthium L.) were prepared via percolation (70% ethanol) from 500-1500 g of dried plant powder and concentrated by vacuum distillation (40°C). Phytochemicals were identified using standard reagents. Rice weevils (Sitophilus oryzae) were reared in an insectary and used as a bioindicator. Contact toxicity and repellency tests (McDonald et al., 1970) were conducted with 20 adult weevils in three replicates. Results: The LC50 values of extracts of Absinthium, Eucalyptus, Tobacco, and Asafoetida plants were estimated to be 453.05, 470.59, 716.55, and 850.73 mg/ml, respectively. The results of the tests showed that eucalyptus extracts with 98.33% had the highest mortality effect against S. oryzae, compared to Asafoetida, Tobacco, and Absinthium extracts with 96.66%, 93.33%, and 91.66%, respectively. Moreover, in the repellent test, the extract of Asafoetida showed the highest repellent effect with 86.66%, compared to the extracts of Tobacco, Eucalyptus, and Absinthium with 73.33%, 63.33%, and 43.33%, respectively. Conclusion: The evaluated plant extracts, particularly Eucalyptus and Asafoetida, demonstrate high efficacy and reduced environmental and health risks, making them promising alternatives to chemical insecticides for stored-product pest control. These findings support safer pest management strategies to enhance food safety and public health.