In vitro evaluation of essential oils and saturated fatty acids for repellency against the old-world sandfly, Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae)

Authors: Temeyer, Kevin; Schlechte, Kristie; COATS, JOEL - Iowa State University; Cantrell, Charles; ROSARIO-CRUZ, RODRIGO - Universidad Autónoma De Guerrero; Lohmeyer, Kimberly - Kim; Perez De Leon, Adalberto - Beto; Li, Andrew

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/2024
Publication Date: 2/22/2024
Citation: Temeyer, K.B., Schlechte, K.G., Coats, J.R., Cantrell, C.L., Rosario-Cruz, R., Lohmeyer, K.H., Perez De Leon, A.A., Li, A.Y. 2024. In vitro evaluation of essential oils and saturated fatty acids for repellency against the old-world sandfly, Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae). Insects. https://doi.org/10.3390/insects15030155.
DOI: https://doi.org/10.3390/insects15030155

Interpretive Summary: Phlebotomus papatasi is an old-world blood-feeding insect species that transmit pathogens causing leishmaniasis. Sand flies pose a significant threat to U.S. military personnel when deployed to the Middle East and Africa where those disease insect vectors are endemic. With support from the Department of Defense’s Deployed Warfighter Protection (DWFP) Program, USDA ARS scientists led a team of investigators, including university collaborators, to evaluate the effects of two known insect repellent compounds and ten natural products, including six plant essential oil and four saturated fatty acids, against blood-feeding female sand flies through laboratory static air repellency bioassays. Study results indicated tested natural products demonstrated various levels of repellency against sand flies. Time- and concentration-repellency responses were established to allow comparisons among test materials. Essential oils of catnip, amyris and peppermint were identified as effective spatial repellents at reduced concentrations compared to DEET. The results are of interest to military entomologists, insect repellent and public health researchers concerned with sand fly bites of humans and leishmaniasis. Future studies will focus on elucidation of modes of action and potential synergism of repellents and essential oil components for development of more effective sand fly repellent products.

Technical Abstract: The sandfly, Phlebotomus papatasi (Scopoli, 1786), is a major vector for Leishmania major in the Middle East that impacted US Military operations and personnel and demonstrated the need to develop effective sand fly control and repellent options. Here, we report results of spatial repellency and avoidance experiments in a static air olfactometer with adult female P. papatasi testing essential oils of Lippia graveolens (Mexican oregano), Pimenta dioica (allspice), Amyris balsamifera (amyris), Nepeta cataria (catnip), Mentha piperita (peppermint), Melaleuca alternifolia (tea tree), the 9-12 carbon saturated fatty acids (nonanoic acid, decanoic acid, undecanoic acid, and dodecanoic acid), and the synthetic repellents DEET and IR3535. Materials applied at 1% exhibited varying activity levels but were not significantly different in mean repellency and avoidance than DEET and IR3535 except for nonanoic acid. Some materials produced sandfly mortality, particularly nonanoic and undecanoic acids. Observed trends in mean repellency over exposure time included: 1) P. dioica oil, M. alternifolia oil, decanoic acid, undecanoic acid, DEET and IR3535 exhibited increasing mean repellency over time; 2) oils of N. cataria, A. balsamifera, M. piperita and dodecanoic acid exhibited relatively constant mean repellency over time; and 3) L. graveolens oil and nonanoic acid exhibited a general decrease in mean repellent activity over time. These studies identified essential oils of N. cataria, A. balsamifera, and M. piperita as effective spatial repellents at reduced concentrations compared to DEET. Additional research is needed to elucidate modes of action and potential synergism of repellents and essential oil components contributing to repellent activity.