Effect of Artemisia dracunculus L. Water Extracts on Aphis fabae Scop. and Its Predators in Field Conditions

Use of plant-based aqueous extracts offers a potentially simple and low-cost approach to pest control. However, their effectiveness under field conditions remains poorly recognised. The aim of the study was to evaluate the effectiveness of aqueous extracts prepared from dried and fresh Artemisia dracunculus L. plant material (D-Es and F-Es, respectively) in controlling Aphis fabae Scop. in field conditions. D-Es were applied in concentrations of 2% (D2), 5% (D5) and 10% (D10) and F-Es in concentrations of 10% (F10), 20% (F20) and 30% (F30). A reduction in the A. fabae population was observed with the use of both D-Es and F-Es (although not as strong as with chemical control (Ch)), with the greatest effect observed after using D-E at a concentration of 10% (D10-E). In the case of D-Es, the aphid-suppressing effect increased as the extract concentration rose. No similar result was observed for F-Es. Regardless of the concentration used, the individual F-Es did not differ significantly from one another. The strength of the limiting effect on A. fabae was arranged in the following order of treatments: Ch > D10 > F10 > D5 > F20 > D2 > F30. Analysis of the volatile compounds contained in D10-E revealed that the main constituents were methyleugenol (27.7%), elemicine (15.6%), (E)-isoelemicine (12.5%), terpinen-4-ol (9.3%) and linalool (4.3%). The extract exhibited the highest antioxidant activity and the highest concentration of polyphenolic compounds. Reduced numbers of the main aphid predators (syrphids and ladybirds) in the treatments with extracts went along with lower prey availability; however, the predator–prey ratio in these treatments was more favourable than in the control. This suggests that the use of F-Es and D-Es does not adversely affect predator abundance. The ease of preparation and availability of the material make D10-E suitable for use on organic farms or as part of integrated pest management.