My Thi Pham

Resistance to synthetic insecticides has intensified the search for plant-derived biopesticides. Pilea plataniflora C.H.Wright (Urticaceae), a medicinal plant native to Vietnam and China, has a high essential oil yield; however, its essential oil composition and biological activities remain unreported. This study characterized the chemical composition and evaluated the pesticidal and antimicrobial activities of P. plataniflora essential oil collected across three successive years. Chemical composition was determined by GC-MS. Pesticidal activities (larvicidal, repellent, fumigant adulticidal, and molluscicidal) were evaluated following modified WHO guidelines, and antimicrobial activity was assessed by broth microdilution. Three oil samples from the same population showed considerable chemical variation. The 2018 sample (PP18) was dominated by δ-3-carene (44.1%), α-thujene (20.1%), and sabinene (7.2%). The 2019 sample (PP19) comprised δ-3-carene (15.9%), (E)-β-caryophyllene (12.2%), and β-pinene (10.6%). The 2020 sample (PP20) was dominated by δ-3-carene (26.8%), sabinene (11.6%), and terpinen-4-ol (5.5%). All samples exhibited larvicidal activity against mosquito species tested. PP19 and PP20 showed repellent effects against Aedes aegypti (Linnaeus, 1762), with protection times of 133.3±18.8 and 264.8±72.5 min at 50% concentration, respectively. PP19 showed the greatest fumigant adulticidal potency (60-min LC₅₀ = 2.98%). PP18 exhibited antimicrobial activity against Enterococcus faecalis, Staphylococcus aureus, and Candida albicans (MIC: 32-128 µg/mL). This first report on P. plataniflora essential oil demonstrates that this species is a promising source of bioactive compounds with larvicidal, repellent, fumigant, and antimicrobial properties relevant to sustainable vector management and infection control.