Attractant and Repellent Effect of Syzygium aromaticum, Cinnamomum verum and Allium cepa Extracts in Controlling the Ant Solenopsis invicta

Abstract

Introduction: Ants are insect pests that can cause economic and environmental damage, as well as transmit pollutants and microorganisms, necessitating the search for safe alternatives to traditional chemical pesticides. Medicinal and aromatic plants are an important source of active compounds that influence insect behavior, with their effectiveness varying depending on the plant species, extraction method, and solvent, concentration, and exposure duration. The current study aimed to evaluate the repellent efficacy of extracts from several aromatic and medicinal plants, including Syzygium aromaticum, Cinnamomum verum and Allium cepa, against the ant Solenopsis invicta, while also investigating the effect of extract type, concentration, and exposure duration on ant behavior. Methods: Worker ants were collected from three areas in the Karbala Governorate. The study extended from December 2025 to March 2026. Plants were collected from local markets in the province, and the experiment was conducted at the Core Laboratory in the Saif Saad area of Karbala, Department of Biology, and College of Education for Pure Sciences, University of Karbala. The study adopted an experimental approach to evaluate three types of plant extracts: alcoholic, boiled aqueous, and cold aqueous, at four concentrations: 5%, 10%, 15%, and 20%. The ants’ response was monitored after 10 minutes, 30 minutes, one hour, and 24 hours. The repellency and attraction rates were measured, and the differences were statistically analyzed at a probability level of 0.05. Results: The results showed significant differences in the effectiveness of the extracts depending on the plant species, extract type, concentration, and exposure time. The alcoholic extract was generally the most effective. Repellent efficacy increased with increasing concentration and gradually decreased with increasing exposure time. S. aromaticum exhibited the highest ant-repelling efficacy, averaging 94.25%, followed by C. verum at 87.08%, and A. cepa at 72.50%. The highest overall repellent rate, 84.46%, was recorded after 10 minutes, with a clear inverse relationship between repellent and attractant rates. Conclusion: The study concluded that plant extracts, particularly the 20% alcoholic extract of S. aromaticum, possess promising ant-repellent efficacy and could represent a suitable plant-based alternative to traditional chemical pesticides.