Field Application of Tea Volatiles Mediating the Selectivity of Aleurocanthus spiniferus on Four Tea Cultivars

Orange spiny whitefly (Aleurocanthus spiniferus Quaintance) is a major pest with economic significance to tea plants, as both nymphs and adults suck plant sap and contribute to the development of tea sooty mold. The occurrence of this pest varies considerably among different tea cultivars, even within the same plantation. This study aims to characterize the bioactive constituents of tea volatiles mediating A. spiniferus host selection, and leverage these semiochemicals to develop effective field trapping systems. Through field investigations and Y-tube olfactometer tests, we identified two highly preferred tea cultivars ('Huangjinya' and 'Fuding white tea') and two cultivars ('Baiye No. 1' and 'Longjing 43') that were not preferred. Behavioral assays and gas chromatography-mass spectrometry (GC-MS) analysis revealed four attractive compounds [hexanol, (E)-2-hexenal, linalool, and (E,E)-α-farnesene] and two repellent compounds [nonanal and (Z)-3-hexenol] in the volatile emissions of the four cultivars. A hexane solution (10 µL) of nonanol, (Z)-3-hexenol, linalool, and (E,E)-α-farnesene at a concentration of 100 µg/µL was able to elicit an obvious electrophysiological (EAG) response. In field trials, the synergistic bait trap equipped with two types of attractants, 500 µL of hexane solution of the mixture of linalool and (E,E)-α-farnesene (3:1, v/v), and the mixture of linalool and (Z)-3-hexenol (3:1, v/v) at the concentration of 100 μg/μL, showed significantly higher attractant efficacy and selectivity. Overall, this study indicates that tea volatiles play a crucial role in the host selection of A. spiniferus, and the synthetic mixtures of tea volatiles have the potential to be developed as commercial plant-based attractants for adult A. spiniferus. This study contributes to the development of sustainable, environmentally friendly management strategies for a pest that is challenging to prevent and control.