The toxicity of red pine needle hydrodistillate, its constituents, and 12 structurally related compounds to third instar larvae of insecticide-susceptible Aedes aegypti and wild Aedes albopictus was examined using a direct-contact bioassay. Results were compared with those of the currently used larvicides fenthion and temephos. The red pine needle hydrodistillate constituents were identified by GC-MS and co-elution of authenticated samples following co-injection. Based on 24 h LC50 values, 3-carene (8.60–9.33 mg/L), limonene (10.34–10.77 mg/L), and thymol (10.65–11.45 mg/L) were the most toxic constituents. The moderate toxicity was produced by (1S)-(–)-α-pinene, p-cymene, geranyl acetate, myrcene, and β -caryophyllene (LC50, 27.62–38.01 and 28.61–39.52 mg/L). Overall, these compounds were less effective than either fenthion (LC50, 0.012–0.022 mg/L) or temephos (LC50, 0.010–0.015 mg/L). In the light of global efforts to reduce the level of highly toxic synthetic insecticides in the agricultural environment, red pine needle hydrodistillate and the compounds described merit further study as potential larvicides for the control of mosquito populations.

• Seong Chun Chae(Interdisciplinary Program in Agricultural Biotechnology Major, Department of Agricultural Biotechnology, Seoul National University)
• Dong-Chan Lee(Hankuk Academy of Foreign Studies)
• Jun-RanKim(Research Institute for Agriculture and Life Science, Seoul National University, WCU Biomodulation Major, Department of Agricultural Biotechnology, Seoul National University)
• Haribalan Perumalsamy(Research Institute for Agriculture and Life Science, Seoul National University)
• Young-JoonAhn(WCU Biomodulation Major, Department of Agricultural Biotechnology, Seoul National University)