Effects of cover crops on beetle assemblages in tea plantations

Authors: CHEN, LI-LIN - FUJIAN AGRICULTURAL & FORESTRY UNIVERSITY; POZSGAI, GABOR - FUJIAN AGRICULTURAL & FORESTRY UNIVERSITY; LI, XIANG-YU - FUJIAN AGRICULTURAL & FORESTRY UNIVERSITY; LI, LEI - FUJIAN AGRICULTURAL & FORESTRY UNIVERSITY; Reddy, Gadi V.P.; YOU, MIN-SHENG - FUJIAN AGRICULTURAL & FORESTRY UNIVERSITY

Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/31/2021
Publication Date: 8/1/2021
Citation: Chen, L., Pozsgai, G., Li, X., Li, L., Reddy, G.V., You, M. 2021. Effects of cover crops on beetle assemblages in tea plantations. Crop Protection. 149:1-11. https://doi.org/10.1016/j.cropro.2021.105783.
DOI: https://doi.org/10.1016/j.cropro.2021.105783

Interpretive Summary: Tea is a perennial, evergreen shrub that is widely cultivated throughout the tropics and subtropics, particularly in hilly or mountainous regions. Pest damage to tea, however, can reduce its marketability and cause significant losses in yield. Such problems have led to the overuse of pesticides, which in turn can contaminate tea with pesticide residues, cause pest resistance, and induce pest resurgence due to destruction of natural enemies. The beetles (Coleoptera) are an abundant and species-rich order that includes both pests and beneficial species important in tea production. Cover crops can be used to reduce soil erosion, improve soil structure or fertility, increase water infiltration, suppress weeds or nematodes, and improve crop quality. Cover crops that are properly selected and well managed can enhance the abundance and efficacy of natural enemies. We tested the hypothesis that ground covers in tea plantations influence the abundance, biomass, and species richness of both herbivore and predatory beetles, affecting the whole assemblage. We predicted that intercropping in tea would increase natural enemy: pest ratios compared to a naturally weedy control, and that this effect would be equally observable for abundance, biomass, and species richness.

Technical Abstract: Coleoptera are visible members of food webs in tea plantations, with high species richness and abundance. Many tea pests, as well as natural enemies, are members of this order, so a knowledge of how groundcovers affect beetles can aid pest management. We collected beetles in a replicated field experiment in the Wuyi Mountains, Fujian Province, China. Tea was intercropped with Paspalum notatum or Chamaecrista rotundifolia, or rows were cleared to bare ground, or in the control they were left unmanaged to allow weeds to grow naturally. Sampling, done by sweep netting and vegetation beating, was conducted monthly, between May 2006 and April 2008, and Coleoptera abundance, biomass, species richness and assemblage structures were compared between groundcover treatments. Total beetle abundance and species richness were significantly higher in tea intercropped with C. rotundifolia and bare ground than in naturally grown weedy control. Whilst there was no difference between predator assemblages among treatments for any measure, herbivores were more abundant, weighed more, and were more diverse in C. rotundifolia treatments than in weedy control. Biomass and species richness were also greater in plots with P. notatum groundcover than those in weedy control. We found that beetle assemblages varied both seasonally and with ground cover treatment, but the potential pest control impact of more species-rich beetle assemblages was mixed, and further work is needed to gain information on trophic groups with potential benefits for use in non-insecticidal pest management.