Essential oils from two aromatic plants repel the tobacco whitefly Bemisia tabaci

Characterizing the olfactory responses of insect pests is critical for developing biological control options and pest management strategies in the field. Such responses form the basis for evaluating interactions between plants and insects, as well as providing evidence to support the use of non-crop plant types in pest suppression tactics. To evaluate the potential aversion or attraction of Bemisia tabaci MED/Q to volatiles from various plants, behavioral responses of adult whitefly were observed in Y-type olfactometer tests (n = 30 individuals per trial, with 3 replicate trials per treatment combination; n = 4230 individuals in total). We quantified the potential repellent effects of the essential oils of Thymus pulegioides (‘thyme’) and Artemisia absinthium (‘wormwood’) on B. tabaci MED/Q. The essential oil of T. pulegioides as well as three of the four major subcomponents tested (thymol 36.18%, p-Cymene 10.85% and thymol methyl ether 7.45%, but not Carvacrol 13.43%) had significant repellent effects on B. tabaci MED/Q. Similarly, the essential oil of A. absinthium, as well as the two major subcomponents tested (Linalool 23.41% and (−)-β-Pinene 27.88%), had marginally significant repellent effects on B. tabaci MED/Q. In tests across increasing concentrations of these volatile compounds, repellent effects were typically only significant at the two highest concentrations tested. Overall, these results demonstrate that major constituents of certain aromatic plant oils have a strong repellent effect and contact toxicity on B. tabaci MED/Q. These findings have important implications for more environmentally friendly biological control options using aromatic plants to repel target pests in production crops.