Intercropping Cover Crops for a Vital Ecosystem Service: A Review of the Biocontrol of Insect Pests in Tea Agroecosystems

Abstract

The intercropping of cover crops has been adopted in several agroecosystems, including tea agroecosystems, which promotes ecological intensification. Prior studies have shown that growing cover crops in tea plantations provided different ecological services, including the biocontrol of pests. Cover crops enrich soil nutrients, reduce soil erosion, suppress weeds and insect pests, and increase the abundance of natural enemies (predators and parasitoids). We have reviewed the potential cover crops that can be incorporated into the tea agroecosystem, particularly emphasizing the ecological services of cover crops in pest control. Cover crops were categorized into cereals (buckwheat, sorghum), legumes (guar, cowpea, tephrosia, hairy indigo, and sunn hemp), aromatic plants (lavender, marigold, basil, and semen cassiae), and others (maize, mountain pepper, white clover, round-leaf cassia, and creeping indigo). Legumes and aromatic plants are the most potent cover crop species that can be intercropped in monoculture tea plantations due to their exceptional benefits. These cover crop species improve crop diversity and help with atmospheric nitrogen fixation, including with the emission of functional plant volatiles, which enhances the diversity and abundance of natural enemies, thereby assisting in the biocontrol of tea insect pests. The vital ecological services rendered by cover crops to monoculture tea plantations, including regarding the prevalent natural enemies and their pivotal role in the biocontrol of insect pests in the tea plantation, have also been reviewed. Climate-resilient crops (sorghum, cowpea) and volatile blends emitting aromatic plants (semen cassiae, marigold, flemingia) are recommended as cover crops that can be intercropped in tea plantations. These recommended cover crop species attract diverse natural enemies and suppress major tea pests (tea green leaf hopper, white flies, tea aphids, and mirid bugs). It is presumed that the incorporation of cover crops within the rows of tea plantations will be a promising strategy for mitigating pest attacks via the conservation biological control, thereby increasing tea yield and conserving agrobiodiversity. Furthermore, a cropping system with intercropped cover crop species would be environmentally benign and offer the opportunity to increase natural enemy abundance, delaying pest colonization and/or preventing pest outbreaks for pest management sustainability.

Vernicia fordii leaf extract inhibited anthracnose growth by downregulating reactive oxygen species (ROS) levels in vitro and in vivo

“…Rotation and intercropping strategies increase plant resistance to pathogens, enhance antifungal activity, and thus reduce disease incidence ( Han et al, 2016 ; Yu et al, 2019 ). Intensive tea plantations benefited from the inclusion of climate-resilient crops (sorghum, cowpea) and aromatic volatile blends of semen cassiae, marigold, and flemingia as companion crops, mitigating disease and pest risks ( Pokharel et al, 2023 ). Intercropping pest and disease suppression can be attributed to leaf and root extract components and volatiles such as DPT, DMT, and MP that proved vital in suppressing Panama banana disease in breeder practice ( Li et al, 2020 ).…”

Understanding and exploring the diversity of soil microorganisms in tea (Camellia sinensis) gardens: toward sustainable tea production

“…One well known component of tea is caffeine, which can act as a stimulant increasing alertness, with levels of caffeine affected by leaf harvest time and various forms of post-harvest processing. In addition, tea contains a range of secondary metabolites, some of which may possess antioxidant, digestive, (putative) antimicrobial, and/or other health promoting benefits to the consumers (Pokharel et al, 2023;Ramphinwa et al, 2023). Aside from caffeine, potential bioactive compounds include polyphenols (e.g., flavonoids and catechins) as well as xanthines such as theobromine and theophylline.…”

CsAFS2 Gene from the Tea Plant Intercropped with Chinese Chestnut Plays an Important Role in Insect Resistance and Cold Resistance

“…Intercropping, planting multiple crops in the same field rows, is a common agricultural method to enhance production by efficiently utilizing space, improving ventilation and light transmission, and boosting light energy utilization and stress resistance of crops [9]. In Chinese tea production, a notable cultivation technique involves planting trees in tea plantations, notably intercropping tea plants with Chinese chestnut.…”