Grapholita molesta (Busck) (Lepidoptera: Tortricidae) is an important pest of apple, peach, plum, etc. Growers use synthetic chemical insecticides to manage this pest, but G. molesta have developed an insecticide resistance. As botanical insecticides have been rarely studied against G. molesta, we assessed relative toxicity of azadirachtin (azatrol 10 mL/L) in comparison with λ-cyhalothtrin (6.7 mL/20L) in residual assays using both glass scintillation vial coated with the insecticides and apple fruits dipped in the insecticide solutions against first instar larvae (<5 h old) of G. molesta. Azadirachtin showed highest corrected morality of 96.7% at 8h followed by 63.3% in λ-cyhalothtrin in the scintillation vial. On apple dipped in the insecticide solutions, no significance in corrected mortality was found between azadirachtin and λ-cyhalothtrin. Thus azadirachtin can be used as a botanical insecticide for the management of G. molesta.

The toxicity of cypress (Cupressus sempervirens) and howood (Cinnamomum camphora) essential oils, and its constituents to adult western flower thrips, Frankliniella occidentalis using leaf-dipping bioassay and vapour-phase toxicity bioassays. Both cypress and howood essential oils were toxic to western flower thrips. The most active principles were determined to be linalool, linalool oxide, cis-linalool oxide, trans-linalool oxide, camphor, and 1,8-cineole from cypress and howood essential oils. Linalool (24h LC50, 0.030 µg/cm2), linalool oxide (24h LC50, 0.036 µg/cm2), cis-linalool oxide (24h LC50, 0.043 µg/cm2), trans-linalool oxide (24h LC50, 0.045 µg/cm2), and camphor (24h LC50, 0.10 µg/cm2) were the most toxic. Potent toxicity was also observed with 1,8-cineole, a-pinene, d-limonene, a-terpinene, cinnamaldehyde, b-pinene, 3-carene a-terpineol, camphene, and terpineol (24h LC50, 0.33–0.65 µg/cm2). The spray bioassy of cypress and howood oil formulation (500 ppm) resulted in > 80% mortality toward western flower thrips population. Global efforts to reduce the level of toxic synthetic insecticides in the agricultural environment justify further studies on cypress and howood essential oil-derived materials as potential contact-action fumigants for the control of western flower thrips populations.

The toxicity of materials derived from root of Asiasarum heterotropoides against early third instar larvae from susceptible Culex pipiens pallens, Aedes aegypti, and Ochlerotatus togoi was examined using direct contact mortality bioassays. Results were compared with those following the treatment with two currently used mosquito larvicides, temephos and fenthion. The bioactive principles of A. heterotropoides root were identified as asarinin, asarone, methyleugenol, pellitorine, and pentadecane by spectroscopic analysis. As judged by 24 h LC50 values, pellitorine (2.08-2.38 ppm) was the most toxic compound, followed by asarinin (10.49-16.49 ppm) and asarone (22.38-26.99 ppm). These compounds were less toxic than either temephos (0.16-0.20) or fenthion (LC50, 0.23-0.29). Weak activity was produced by methyleugenol (53.30-58.52 ppm) and pentadecane (96.71-99.19 ppm). A. heterotropoides root-derived materials, particularly pellitorine, merit further study as potential mosquito larvicides for protection from humans and domestic animals from vector-borne diseases and nuisance caused by mosquitoes.

The toxicity of melissa and savory essential oil constituents against adult Bemisia tabaci was examined using vapor-phase toxicity bioassay. Results were compared with those following the treatment with currently used insecticide dichlorvos. As judged by 24 h LC50 values, thymol (0.59×10-3 mg/cm3) was the most toxic constituent, followed by cavacrol (0.60×10-3 mg/cm3). These compounds were slightly less toxic than dichlorvos (LC50, 0.20×10-3 mg/cm3). Strong activity was also obtained from borneol (LC50, 1.06×10-3 mg/cm3), α-terpineol (1.22×10-3 mg/cm3), geraniol (1.23×10-3 mg/cm3), linalool (1.33×10-3 mg/cm3), lavendulol (1.44×10-3 mg/cm3), nerol (1.52×10-3 mg/cm3), β-citronellol (1.81×10-3 mg/cm3), terpinene-4-ol (1.87×10-3 mg/cm3), 1-octen-3-ol (2.06×10-3 mg/cm3), and citral (2.34×10-3 mg/cm3). The melissa and savory essential oil-derived compounds, particularly thymol and carvacrol, merit further study as potential insecticides for the control of B. tabaci.