Topical mosquito repellency of a Litsea cubeba essential oil spray against Aedes aegypti, Anopheles dirus, and Culex quinquefasciatus.

Mosquito-borne diseases remain an important global public health concern, and increasing insecticide resistance has strengthened interest in complementary personal protection tools. This study evaluated the short-term dermal tolerability and laboratory repellency of MosShield, a ready-to-use topical spray formulated with 6% w/w Litsea cubeba essential oil. Non-confidential formulation quality-control parameters, including appearance, homogeneity, pH, density, and apparent viscosity, were recorded to support formulation consistency before testing. Short-term dermal tolerability was assessed using a human skin-patch test in 48 healthy volunteers, with no visible skin reactions observed up to 96 h after application. Repellency assays were conducted following the World Health Organization arm-in-cage protocol against three medically important mosquito species: Aedes aegypti, Anopheles dirus, and Culex quinquefasciatus. The formulation showed species-dependent repellency, achieving median complete protection times of 225 min against Cx. quinquefasciatus and 120 min against both Ae. aegypti and An. dirus. These findings provide product-relevant laboratory evidence supporting further evaluation of the 6% L. cubeba essential oil spray as a plant-based topical mosquito repellent under semi-field and field conditions.