Study summary
Topical mosquito repellency of a Litsea cubeba essential oil spray against Aedes aegypti, Anopheles dirus, and Culex quinquefasciatus
Sutthanont N, Leanpolchareanchai J, Sriwichai P, Ruangsittichai J, Phanpoowong T, Sumruayphol S, Phanitchat T, Sakai T, Eshita Y, Srisawat R
Read the original paper- Study type
- Lab
- Year
- 2026
- Sample size
- 48 subjects
- Species tested
- Aedes aegypti; Anopheles dirus; Culex quinquefasciatus
- Published in
- Scientific Reports (2026), DOI 10.1038/s41598-026-61769-z
- Evidence strength
- Limited evidence
How it was tested
WHO arm-in-cage tests of a ready-to-use 6% w/w Litsea cubeba spray (MosShield) against three mosquito species, benchmarked against an 11% citronella comparator (Soffell Spray Natural), plus a skin-patch tolerability test in 48 volunteers scored to 96 hours. Note: this study defined protection failure as the second confirmed landing or probing event, a more lenient endpoint than the first-bite definition used by studies such as Fradin and Day (2002).
What it measured
Measured complete protection time, by arm
Commercial comparator; significantly beat MosShield (p < 0.001). 360 min was the observation ceiling.
Commercial comparator; significantly beat MosShield (p < 0.001).
Median CPT (IQR 150 to 307.5); may chang spray with a vanillin fixative.
Commercial comparator; significantly beat MosShield (p < 0.001).
Median CPT (IQR 120 to 180); only just met the Thai FDA 120-minute minimum.
Median CPT (IQR 90 to 120); only just met the Thai FDA 120-minute minimum.
Complete protection time = minutes until the second confirmed landing or probing event (a more lenient endpoint than the first-bite definition used by most studies here).
Summary
Laboratory efficacy and short-term skin-tolerability study of a ready-to-use topical spray (MosShield) containing 6% w/w Litsea cubeba essential oil, the citral-rich oil pressed from may chang fruit. Repellency was measured with the WHO arm-in-cage complete-protection-time protocol against three medically important mosquito species, and dermal tolerability was checked with a human skin-patch test in 48 healthy volunteers.
Key findings
The tested product (MosShield) is a formulated spray, not neat oil: alongside 6% Litsea cubeba essential oil it uses vanillin as a fixative to slow evaporation, plus an alcohol carrier, a PEG-40 solubilizer, and a dipropylene glycol stabilizer. It gave a median complete protection time of 225 minutes (about 3.75 hours) against Culex quinquefasciatus and 120 minutes (2 hours) against both Aedes aegypti and Anopheles dirus, so protection was real but species-dependent and strongest against Culex. In the 48-volunteer patch test, no visible skin reactions were observed up to 96 hours after application. Litsea cubeba oil is one of the richest natural sources of citral (geranial plus neral), the constituent generally credited with its repellent activity, but because citral is volatile the multi-hour protection here reflects the vanillin fixative as much as the oil, so neat Litsea cubeba oil would be expected to fade faster.
Limitations
Single laboratory arm-in-cage study of one proprietary formulation against caged, colony-reared mosquitoes rather than free-flying wild populations, and the authors frame it as justification for later field testing rather than a finished field result. Protection failure here was defined as the second confirmed landing or probing event, a more lenient endpoint than the first-bite standard used by studies such as Fradin and Day (2002), which lengthens the reported times and makes them hard to compare across studies. In the study's own paired comparison an ordinary 11% citronella spray (Soffell Spray Natural) significantly outperformed the may chang product on all three species (median 360, 300 and 150 minutes versus 225, 120 and 120; p < 0.001), and MosShield only just met the Thai FDA 120-minute minimum against Aedes and Anopheles. Two to nearly four hours of complete protection is useful for an evening outdoors but is shorter than high-concentration DEET or picaridin, so reapplication is needed for longer exposure. The patch test covers only short-term tolerability (96 hours), not repeated or long-term use, and citral is a known dermal sensitizer, so tolerance can differ across skin types. Exact excipient concentrations are protected as trade secrets, and the results have not been independently replicated or confirmed in the field.