Chemical Composition and Potential Control Three Disease‐Transmitting Mosquitoes of <i>Harrisonia perforata</i> (Blanco) Merr. Essential Oils

ABSTRACT The leaf essential oils of Harrisonia perforata , collected at three different times in Vietnam (HP1, HP2 and HP3), were chemically analysed and evaluated for their insecticidal activities against three medically important mosquito species: Aedes aegypti , Aedes albopictus and Culex quinquefasciatus . HP1 was rich in sesquiterpenoids such as caryophyllene oxide (26.3%), ( E )‐β‐caryophyllene (16.9%) and spathulenol (9.7%). HP2 shared similar major constituents with HP1 but contained an unidentified compound (8.2%) and palmitic acid (5.1%). In contrast, HP3 had a lower caryophyllene oxide content (13.5%) and was dominated by α‐santalene (20.5%). Larvicidal assays against Ae. aegypti , Ae. albopictus and Cx. quinquefasciatus revealed that HP3 exhibited the highest toxicity, with 24‐h LC 50 values between 46.13 and 75.83 μg/mL. HP1 and HP3 also demonstrated superior repellent activity at both 10% and 50% concentrations, with HP3 outperforming DEET 10%. Although the knockdown effect was slow, noticeable fumigant toxicity was observed after 60 min for HP1 and HP3, and after 120 min for HP2. All samples exhibited significant fumigant action, with 1440‐min LC 50 values ranging from 0.20% to 0.46% for A. aegypti and 0.03%–0.60% for Cx. quinquefasciatus .