Various effects of volatile constituents from Magnolia kobus flowers against Aedes albopictus (Diptera: Culicidae)

The insecticidal and repellent activities of the floral-derived constituents of Magnolia kobus, i.e., linalool, cinnamyl alcohol and famesene, were investigated against the Asian tiger mosquito Aedes albopictus (Skuse). The main constituents of M. kobus flowers in the early and full-bloom floral stages were obtained using solid phase microextraction (SPME) and analyzed by gas chromatography-mass spectroscopy (GC-MS). The main compounds were the same at both floral stages, though their content ratios differed significantly. The larvicidal activity of the chemical constituents of the full-bloom floral stage caused higher mortality than did constituents of the early floral stage (48 h LC50 = 20.17 ppm and 36.68 ppm, respectively). Adulticidal activity was determined by a topical application method, but there was no significant difference between the materials. The fumigant activity against adult female Ae. albopictus was high in the early floral stage (48 h LD50 = 0.14 mg/cm(3)), which appeared to be due to the high linalool content (32.9 %) at this time, and the chemical constituents of this stage showed high repellency. All materials exhibited concentration-dependent activity after 2 h of treatment with N,N-diethyl-meta-toluamide (DEET) as a positive control. In conclusion, application of all M. kobus floral-derived materials described herein either as a mixture or as individual compounds may be useful for managing Asian tiger mosquito, Ae. albopictus, populations.