Chimpanzee-Inspired Chemical Ecology: GC–MS Analysis of Tree Essential Oils with Anti-Mosquito Activity

Vector-borne diseases such as malaria are the cause of death for one million people worldwide every year, especially in African countries. Efforts to overcome this worldwide burden, including strategies to control vectors, are currently under investigation. Among these efforts is the study of the behavior of chimpanzees, our closest relatives, living in African forests. In Kibale National Park in Uganda, chimpanzees were found to eat plants that are biologically active against the mosquito Plasmodium falciparum (which is responsible for malaria) but also select tree species to build their nests. The essential oils extracted from their leaves have repellent effects on the mosquito Anopheles gambiae, which are vectors of P. falciparum. Researchers investigated the chemical composition and repellent properties of essential oils (EOs) from four tree species in the chimpanzee habitat, three of which are used by chimpanzees for nest construction, using gas chromatography‒mass spectrometry. While these plants are known in traditional African medicine, the essential oil compositions of several species had not been previously characterized. After identifying the oils’ components, the authors evaluated known and tested repellent, irritant, and toxic effects of major compounds against An. gambiae, aiming to develop mosquito control strategies inspired by chimpanzee behavior that avoid environmental overharvesting.A paper based on this research was published in Malaria Journal. (1)

Terrestrial and marine organisms—including plants, animals, and microbes—have long served as rich and enduring sources of chemically diverse, biologically active compounds, while also providing continual inspiration for humankind in the battle against disease. (2,3). With the recent development of advanced analytical chemistry tools, the isolation of natural products (NPs) has been made easier, which allows for the development of other applications that range from cosmetics and perfumery sectors to agriculture through the development of biocontrol agents (4). Tropical forests have become hopeful sources of new compounds, with native plant species there presenting a larger amount of defense metabolites than plants inhabiting temperate forests. There have been authors who proposed that these differences might be explained by the fact that tropical plants are more susceptible to attack by pathogens, herbivorous mammals, and especially insects than are plants in temperate forests (5).

To investigate the chemodiversity of trees used by chimpanzees, EOs from the leaves of Vepris nobilis, Lepisanthes senegalensis, Turraeanthus africanus, and volatile extracts from the leaves of Celtis africana, which are not used for nesting by chimpanzees, were studied, as previously mentioned, via GC–MS. The repellent, irritant, and toxic activities of the compounds selected based on their abundance, availability, and previously studied properties were subsequently tested under laboratory conditions alone and in mixtures on female An. gambiae. (1)

The researchers found that volatile compounds were abundant at concentrations greater than 0.1% in the four plants analyzed. In addition, they discovered different chemical profiles between the three EOs and the volatile extract, with molecules present in the essential oils such as β-elemene, δ-elemene, caryophyllene, α-humulene, or germacrene D. Chemical families specific to Celtis africana include aldehydes, ketones, carboxylic acids, furans, and vinylphenols. Only linalool was present in all four extracts. The researchers then prepared and tested a mixture on mosquitoes that contained α-humulene, caryophyllene, linalool, and citral, and found that the mixture was toxic and an irritant to An. gambiae. (1)

“This study,” write the authors of the study, “describes volatile compounds present at more than 0.1% in the leaves of four species of Ugandan trees. Certain molecules present only in species used by chimpanzees in their nests can be combined to prepare solutions with anti-mosquito properties.” The researchers believe that the outcome of this work could lead to the formulation of a repellent spray against An. gambiae to add a means of malaria prevention. (1)

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References

1. Peti-Jean, E.; Lacroux, C.; Rugonge, H. et al. Draw Inspiration from Research on the Insecticidal, Irritant and Mosquito-Repellent Properties of Plants Used by Chimpanzees to Build Their Nests. Malar J. 2026.DOI: 10.1186/s12936-026-05805-3
2. Benyus J. M. Biomimicry: Innovation Inspired by Nature. Morrow, 1997.
3. Winters A. J.; Adams, M. A.; Bleby, T. M. et al. Emissions of Isoprene, Monoterpene and Short-Chained Carbonyl Compounds from Eucalyptus Spp. in Southern Australia. Atmos. Environ. 2009, 43 (19), 3035–3043. DOI: 10.1016/j.atmosenv.2009.03.026
4. Cantrell, C. L.; Dayan, F. E.; Duke, S. O. Natural Products as Sources for New Pesticides. J. Nat. Prod. 2012, 75 (6), 1231–1242. DOI: 10.1021/np300024u
5. Coley, P. D.; Aide, T. M. Comparison of Herbivory and Plant Defenses in Temperate and Tropical Broad-Leaf Forests; in Plant-Animal Interactions: Evolutionary Ecology in Tropical and Temperate Regions; Price P., Lewinsohn, T. M., Wilson Fernandes, G., Benson, W.W. Editors; Wiley, 1991, 25–49.