Essential oils (EOs) derived from plants are commonly used in various industries such as detergents, cosmetics, pharmacology, and food additives due to their safety profile and numerous health benefits. In addition to these uses, EOs have also been found to have insect-repellent properties by inducing neurotoxic effects. Terpenoids, found in abundance in plant EOs, play a key role in regulating plant defense responses by influencing the expression of defense genes. For example, when soybean and komatsuna plants are grown near mint plants, they experience improved defense properties and become resistant to herbivores through a process called “eavesdropping,” where volatile compounds released by the mint trigger the activation of defense genes.
Although chemical pesticides are widely used for crop protection, their environmental impact and the need to increase food productivity have raised concerns, emphasizing the need for safer alternatives. Plant defense activators have garnered attention as a potential solution, with plant EOs being considered as environmentally friendly candidates. However, there is a lack of proven examples to support their efficacy. To address this gap, a research team led by Prof. Gen-ichiro Arimura from the Tokyo University of Science investigated the effectiveness of 11 EOs in activating tomato defense responses. The team’s findings were published in the Journal of Agricultural and Food Chemistry, demonstrating the potential of EOs as pest resistance enhancers.
The study focused on the effects of terpenoid-enriched EOs on tomato plants, observing that rose EO (REO) increased the expression levels of defense genes in tomato leaves. Treatment with REO also led to reduced leaf damage by moth larvae and mite pests. Field experiments further confirmed the efficacy of REO in reducing tomato pest damage, positioning it as a promising alternative to chemical pesticides, particularly during milder seasons. With β-citronellol, an insect repellent, as a key component, REO was found to effectively minimize damage caused by pests while attracting their predators, showcasing its dual functionality in pest management.
The research findings highlight the potential of β-citronellol-enriched EO like REO in activating defense genes in tomato plants, enhancing their resilience against pests without adverse effects. This study opens avenues for promoting organic tomato production through environmentally friendly and sustainable practices, reducing reliance on harmful pesticides. Prof. Arimura envisions a shift towards more natural and eco-friendly agricultural practices, laying the groundwork for the development of potent natural pesticides. The study’s results offer a practical approach to enhancing plant defense mechanisms and fostering organic farming systems, encouraging a more sustainable approach to pest management in agriculture.
