Bioactivity of Wild Carrot (Daucus carota, Apiaceae) Essential Oil Against Mosquito Larvae.

Invasive alien plants wreak havoc on native ecosystems and using them as a source of biopesticides could improve their management. We examined the toxicity of essential oil of wild carrot (also known as 'Queen Anne's Lace', Daucus carota Linnaeus), an aggressive invader throughout the United States, against Aedes aegypti L., Culex pipiens L., and Culex restuans Theobald larvae. Comparisons were made between essential oil extracted from umbels of local populations of wild carrot versus a commercial brand. Methyl isoeugenol (60.7%) was by far the most abundant constituent in commercial brand oil, whereas α-pinene (33.0%) and β-pinene (25.8%) were the dominant constituents in essential oil extracted from local wild carrot populations. The commercial brand essential oil was significantly more toxic to Cx. restuans larvae (LC50 = 44.4 ppm) compared with Cx. pipiens (LC50 = 51.0 ppm) and Ae. aegypti (LC50 = 54.5 ppm). Essential oil from local populations of wild carrot was significantly more toxic to both Cx. pipiens (LC50 = 42.9) and Cx. restuans (LC50 = 40.3) larvae compared with Ae. aegypti (LC50 = 64.6 ppm) larvae. Three of the nine tested chemical constituents of wild carrot essential oil (terpinolene, para cymene, and γ-terpinene) were consistently more toxic to larvae of the three mosquito species than the whole essential oil. These findings suggest that exploiting wild carrot essential oil and its chemical constituents as a biopesticide for mosquito control could be used as part of multifaceted approaches for controlling this invasive alien plant species.