Organic tea farmers use companion planting to suppress pests. Controlled experiments measured which plant combinations reduce leafhopper damage without chemicals.
Ecological engineering in a teacup
In the Wuyi Mountains of China's Fujian province, a UNESCO World Heritage site, the tea plant Camellia sinensis faces a persistent threat. The tea green leafhopper, Empoasca onukii, is a sap-sucking insect that can cause significant damage to tea leaves, reducing both yield and quality. While chemical pesticides are one solution, a growing interest in organic and sustainable farming has led researchers to explore ecological engineering—manipulating the farm environment to manage pests naturally. One of the most effective methods is intercropping, the practice of planting other crops alongside the main cash crop.
Controlled studies in the Wuyi Mountains and other tea-growing regions of China have tested the effectiveness of various companion plants. The goal is to find plants that either repel the leafhoppers or attract their natural enemies. By creating a more diverse agroecosystem, farmers can reduce their reliance on pesticides and promote a healthier environment. This approach turns the tea plantation into complex interactions where pests are kept in check by a thriving population of predators.
A push-pull experiment
The strategy often involves a "push-pull" approach. Some companion plants "push" pests away with repellent volatile organic compounds (VOCs), while others "pull" in beneficial predators. Scientists have measured the specific effects of intercropping various aromatic and leguminous plants with tea. For example, planting lavender (Lavandula pinnata) has been shown to repel tea green leafhoppers due to the odors it releases. Similarly, intercropping with marigold (Tagetes erecta) and Flemingia macrophylla can reduce leafhopper populations by releasing a blend of volatile attractants, including cis-3-hexen-1-ol and α-farnesene.
The "pull" part of the strategy is just as important. Intercropping tea with plants like Cassia tora significantly increases the populations of natural leafhopper enemies, such as ladybird beetles, lacewings, and spiders. In some experiments, the diversity of important spider predators increased, helping to suppress the leafhopper population. Studies on intercropping with cover crops like Chamaecrista rotundifolia have found that they provide better microhabitats for predators to build nests and find shelter, boosting their numbers. The results are ecological and intercropping with legumes like soybeans and cowpeas can also increase the foliar concentrations of desirable compounds in the tea leaves themselves, such as caffeine and theanine, thereby improving the tea's final quality.
💡Fun Facts
The tea green leafhopper, once considered a pest, can sometimes be an asset. Its feeding can trigger the tea plant to produce unique secondary metabolites that create the sought-after "honey" flavor in premium teas like Taiwan's "Oriental Beauty."
The scientific name for the tea green leafhopper has been a point of confusion for decades, with researchers in China, Taiwan, and Japan identifying it as different species (*Empoasca vitis*, *Jacobiasca formosana*, and *Empoasca onukii*, respectively) before genetic analysis suggested they were all the same species.
The Wuyi Mountains are a UNESCO World Heritage Site for both their cultural significance in neo-Confucianism and their outstanding biodiversity.
Some companion plants used in tea plantations, like marigolds, release semiochemicals—compounds that act as signals—that can effectively repel pests without synthetic pesticides.
The Wuyi Mountains Scenic Area is generally open daily from 7:00 AM to 5:30 PM, but access to specific tea fields may vary.
Admission
An entrance ticket is required for the main scenic area, with prices varying based on the duration of the pass.
Accessibility
The terrain includes many steep, stone-paved mountain paths. Accessibility is limited for individuals with mobility challenges. Lower-altitude tea plantations may be easier to visit.