Effects of intercropping tea with aromatic plants on population dynamics of arthropods in Chinese tea plantations

Abstract

Tea plants (Camellia sinensis (L.) O. Kuntze) are often colonized by economically important insect pests such as tea green leafhoppers (Empoasca onukii Matsuda) and green plant bugs (Apolygus lucorum Meyer-Dur) in northern China. Aromatic plant volatiles can exert repellent effects on insect herbivores. To evaluate the impact of intercropping on the populations of two tea pests and natural enemies in tea plantations, field experiments were conducted in which four aromatic plants (Cassia tora, Medicago sativa, Leonurus artemisia, and Mentha haplocalyx) were intercropped with tea plants and compared with tea monoculture in 2014 and 2015. The counts of arthropods conducted on tea plants showed that intercropping C. tora and L. artemisia with tea plants significantly reduced the E. onukii population levels in the tea plantation. The abundance of A. lucorum was variable during the study and not significantly lower in various intercropping plots than monocropping plots. Y-tube olfactometer assays showed that volatile organic compounds derived from C. tora and M. sativa significantly affected the behavior of E. onukii and that M. haplocalyx odors can be used to mask host plant odors and are repellent to A. lucorum. Among natural enemies, coccinellids occurred often on tea plants during growing seasons. Intercropping tea plants with C. tora also promoted a marked increase in the natural enemies of tea pests, including coccinellids, lacewings, spiders, and parasitoids. Our findings suggest that the sustainable pest management achieved by intercropping offers an alternative strategy for the control of important tea pests.