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.

This study was conducted to determine the toxicity to adult Myzus persicae (Sulzer) and Aphis gossypii Glover of 88 plant essential oils and six experimental spray formulations containing bitter orange or marjoram oil was examined using the vapor-phase mortality and spray bioassays. Results were compared with those of two conventional insecticides deltamethrin and dichlorvos. As judged by 24 h LC50 values, bitter orange oil (0.0212 and 0.0192 mg/cm3) was the most active material, followed by marjoram, celeryseed, and cypress oils (0.0239-0.0508 and 0.0209-0.0542 mg/cm3). These essential oils were significantly less toxic than dichlorvos, respectively. These essential oils were consistently more toxic to adult M. persicae in closed versus open containers, indicating that toxicity was achieved mainly through the action of vapor. Bitter orange oil and marjoram oil applied as 1% spray provided complete mortality toward two aphid species adults. Reasonable aphid control in greenhouses can be achieved by a spray formulation containing the 1% oil as potential contact-action fumigant.

This study was aimed at assessing the fumigant toxicity to adult Thrips palmi and Orius strigicollis of basil (Ocimum basilicum) essential oil compounds and structurally related compounds using vapour-phase toxicity bioassays. Results were compared with those for dichlorvos. Against adult T. palmi, linalool (LD50, 0.0055 mg cm–3) was the most toxic fumigant and was 15.2–fold more effective than dichlorvos (0.0837 mg cm–3). Strong fumigant toxicity was also observed in pulegone (0.0095 mg cm–3), (±)-camphor (0.0097 mg cm–3) and 1,8-cineole (0.0167 mg cm–3). Moderate toxicity was produced by camphene, 3-carene, (–)-menthone, (+)-α-pinene, (+)-β-pinene, α-terpineol and (–)-α-thujone (0.0215–0.0388 mg cm–3). Against adult O. strigicollis, dichlorvos (LD50, 9.0 ×10–10 mg cm–3) was the most toxic fumigant, whereas the LD50 values of these compounds ranged from 0.0127 to >0.23 mg cm–3. Based upon selective toxicity ratio (STR, O. strigicollis LD50/T. palmi LD50), the compounds described (STR, 0.7–>10.7) are more selective than dichlorvos (STR, 10.8×10–9 mg cm–3). Basil oil compounds described merit further study as potential insecticides for control of T. palmi in greenhouses because of their generally lower toxicity to O. strigicollis and their greater activity as a fumigant than dichlorvos.

The toxicity of methanol extract from 28 plants toward four agricultural insect pests were examined using contact toxicity bioassay with spray methods. At a concentration of 1,000 ppm Achyranthes japonica whole body was observed strong activity against Myzus persicae. Paeonia lactiflora root and Corydalis turtschaninovii rhizome methanol extract were observed strong activity toward Tetranychus urticae. Catalpa ovata leaf and Ginkgo biloba leaf and stem methanol extracts were revealed high activity toward Nilaparvata lugens. Actium lap root methanol extract was observed moderate activity against Plutella xylostella. High or moderate insecticidal activity of plant extracts were listed in Fig.1. These plant resource, particularly plant methanol extract or insecticidal constituents, merit further as potential insect pest control agents or leads because of their great activity as a insecticide.