Artemisia arborescens "Powis Castle" extracts and α-thujone prevent fruit infestation by codling moth neonates

The codling moth, Cydia pomonella L. (Tortricidae), is a major cosmopolitan pest of the apple. The potential of plant-derived semiochemicals for codling moth control is poorly studied.

To evaluate the potential of crude extracts of five plants from the Asteraceae family: Artemisia absinthium L., Artemisia arborescens L. "Powis Castle", Artemisia annua L., and Artemisia ludoviciana Nutt. to prevent apple infestation by C. pomonella larvae and to identify the deterrent(s) in these plants.

Artemisia dried leaves were extracted in v/v mixture of 80% ethanol, 10% isopropanol, and 10% of methanol, and the extracts were analyzed using high-performance thin layer chromatography. Preference of fruit treated with test solutions (Artemisia extracts or α-thujone) versus fruit treated with solvent was studied using choice assays.

α-Thujone was detected in A. arborescens extract at a concentration of 77.4 ± 2.4 mg/g of dry tissue, localized between Rf 0.75 and 0.79 and was absent from crude extracts of remaining Artemisia species. Material from each extract in the zone between Rf 0.75 and 0.79 was removed from chromatographic plates and tested for feeding deterrence. Only the material from A. arborescens showed feeding deterrent properties. Minimum concentrations that prevented fruit infestation were 10 mg/ml for α-thujone and 1 mg/ml for A. arborescens crude extract.

Artemisia arborescens contains chemicals that prevent apple infestation by codling moth neonates. Thujone is one of these chemicals, but it is not the only constituent of A. arborescens crude extract that prevents fruit infestation by codling moth neonates.