In Vivo Bioassay of the Repellent Activity of Caraway Essential Oil against Green Peach Aphid

SIMPLE SUMMARY: The green peach aphid (Myzus persicae (Sulzer)) is considered one of the main pests of economically valuable crops. In the last decades, it has developed resistance to several chemical pesticides. More effective and environmentally friendly solutions for green peach aphid management, including plant essential oils, are being tested as alternatives to chemical pesticides. Repellents have gained interest because lower doses can be used against agricultural pests, with a reduced risk of developing insect resistance. In this study, three different types of caraway (Carum carvi L.) seed essential oils against green peach aphids were tested. Repellent activity testing was carried out using a bridge method and host plants of white cabbage. The aphids were placed on the bridge, and their choice was recorded depending on whether they went to the treatment side (containing the selected essential oil) or the control side (no essential oil). All the selected caraway essential oils showed that they repel aphids to various degrees. The optimal essential oil dose was determined in the same way. In addition, the essential oil was mixed with different surfactants to create a formulation basis for ready-to-use products, but the testing showed decreased repellent activity of such mixtures. ABSTRACT: An in vivo dual choice bioassay with white cabbage as a host plant was used to determine the repellent effect of three different accessions of caraway (Carum carvi L.) essential oils (EOs) against the green peach aphid Myzus persicae (Sulzer). The dominant components of the EO were D-Carvone (47.3–74.4%) and D-limonene (25.2–51.9%), which accounted for 99.2–99.5% of the EOs determined by GC/MS. The EO with the highest D-limonene content (51.9%) showed the highest repellence (Repellency Index (RI) = +41%), which was stable up to 330 min. The incorporation of several surfactants with different hydrophilic-lipophilic balance values (from 12.4 to 16.7) with caraway EO caused a general inhibition of the repellent effect during the testing period (RI from +41% to −19%). Overall, the findings indicate that caraway EO could be used as a green peach aphid repellent, but more work is needed to formulate the EO into a ready-to-use product.