Chemical Characterization, Insecticidal and Antimicrobial Activity of Pelargonium, Lemongrass, Eucalyptus and Castor Bean Essential Oils against Culex pipiens

Aboelela, Heba M.; Mady, Heba Y.; Baz, Mohamed M.; Basuony, Gehad A.; Ali, Amira T.

doi:10.21608/eajbse.2025.451071

Chemical Characterization, Insecticidal and Antimicrobial Activity of Pelargonium, Lemongrass, Eucalyptus and Castor Bean Essential Oils against Culex pipiens

Document Type : Original Article

Authors

¹ Medical Parasitology Department, Faculty of Medicine, Benha University, Egypt.

² Zoology Department, Women College, Ain Shams University, Cairo, Egypt.

³ Entomology Department, Faculty of Science, Benha University, Benha 13518, Egypt.

⁴ Department of Medical Parasitology, Faculty of Medicine, Cairo University, Egypt.

10.21608/eajbse.2025.451071

Abstract

Mosquitoes, among the most lethal creatures on Earth, are responsible for millions of deaths annually through the transmission of various human diseases. The widespread application of pesticides resulted in significant health issues for humans, environmental degradation, and mosquito resistance to synthetic insecticides. This study sought to evaluate four essential oils and their phytochemical profiles against larvae and adult Culex pipiens. The oils were tested at different concentrations ranging from 25 to 1000 ppm for larvae. Mortality was evaluated after 24 and 48 h, while concentrations from 0.1% to 1% were tested against female mosquito adults after 60 min of exposure. All the tested essential oils demonstrated larvicidal activity, with mortality rates after 24 hours ranging from 90% to 100% at a concentration of 1000 ppm. Eucalyptus camaldulensis oil showed the highest efficacy, achieving 100% larval mortality at 1000 ppm (LC₅₀ = 305.3 ppm), followed by castor bean (Ricinus communis) oil (LC₅₀ = 388.3 ppm) and pelargonium (Pelargonium graveolens) oil that induced 98% mortality (LC₅₀ = 446.2 ppm). Lemongrass (Cymbopogon citratus) oil exhibited the lowest larvicidal activity at 1000 ppm with 90% mortality (LC₅₀ = 491.5 ppm). Pelargonium, lemongrass, and eucalyptus oils showed high adulticidal activity against female Cx. pipiens, achieving 100% mortality at 1% concentration after 60 min. Eucalyptus and pelargonium oils also demonstrated significant antibacterial efficacy among which eucalyptus oil demonstrated the highest overall activity, with inhibition zones reaching 25 mm against Bacillus subtilis and Candida albicans while Klebsiella pneumoniae and Salmonella typhi showed moderate sensitivity, with inhibition zones reaching up to 14 mm and 19 mm. GC-MS analysis of oils revealed various bioactive phytochemicals, including sesquiterpenes, aliphatic alcohols, and fatty acids, which may account for the reported effects.

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