Abstract
The use of ground cover vegetation is becoming a prominent way of promoting biodiversity and associated ecosystem services in Chinese orchards. Despite the large number of studies that have addressed the effects of ground cover vegetation on promoting natural enemy populations and related pest control, it is still unclear whether enhanced natural pest control can increase yield and reduce the use of pesticide. We performed an experiment comparing three cover vegetation practices (ryegrass, clover and hairy vetch) versus a bare ground control in commercial pear orchards in the Yangtze River Delta of East China (YRDEC), China. Natural enemy density (predator and parasitoid abundance), invertebrate herbivore performance (piercing-sucking herbivore abundance and branch-boring and fruit-boring percentage), pesticide input, and pear fruit yield were recorded. The results indicated that cover vegetation decreased herbivore abundance and boring percentage by 50% and 64%, respectively, thus decreasing pesticide use by 26%. We also found that cover vegetation increased the abundance of natural enemies by 621%, and increased pear fruit yield by 7%. Piecewise structural equation modelling confirmed that increased natural enemy densities, decreased herbivore performance by 102%, pesticide use by 51% and increased fruit yield by 10%. This study suggests that the use of ground cover vegetations, especially with clover and hairy vetch, is an effective way of promoting biocontrol services and associated ecosystem services in pear orchards.