1. Ecology
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Increasing plant diversity with border crops reduces insecticide use and increases crop yield in urban agriculture

  1. Nian-Feng Wan
  2. You-Ming Cai
  3. Yan-Jun Shen
  4. Xiang-Yun Ji
  5. Xiang-Wen Wu
  6. Xiang-Rong Zheng
  7. Wei Cheng
  8. Jun Li
  9. Yao-Pei Jiang
  10. Xin Chen
  11. Jacob Weiner
  12. Jie-Xian Jiang  Is a corresponding author
  13. Ming Nie
  14. Rui-Ting Ju
  15. Tao Yuan
  16. Jian-Jun Tang
  17. Wei-Dong Tian
  18. Hao Zhang
  19. Bo Li  Is a corresponding author
  1. Shanghai Academy of Agricultural Sciences, Shanghai Key Laboratory of Protected Horticultural Technology, Shanghai Engineering Research Centre of Low-carbon Agriculture, China
  2. Shanghai Chongming Dongtan Wetland Ecosystem Research Station, Institute of Biostatistics, Shanghai Institute of Eco-Chongming, (SIEC), Fudan University, China
  3. Chongming Agricultural Technology Extension and Service Center, China
  4. Shanghai Agricultural Technology Extension and Service Center, China
  5. Climate Center of Shanghai, China
  6. Zhejiang University, China
  7. University of Copenhagen, Denmark
Research Article
Cite this article as: eLife 2018;7:e35103 doi: 10.7554/eLife.35103
15 figures and 1 additional file

Figures

Twenty-eight mono-rice (red dots) and six plant-diversified community farms (green dots) monitored in Shanghai, China.
https://doi.org/10.7554/eLife.35103.002
Figure 1—source data 1

Site, rice pest and predator populations, insecticide use, and yield data for comparison of plant-diversified farms (treatment) and mono-rice farms (control) in Shanghai, China.

https://doi.org/10.7554/eLife.35103.003
Figure 1—source data 2

Chemical insecticides applied to control the main insect pests on plant-diversified farms and mono-rice farms in Shanghai, China from 2001 to 2015.

The crosses indicate, for each insecticide, when they were used.

https://doi.org/10.7554/eLife.35103.004
Population dynamics of pink rice borer and brown planthopper trapped in the lamp and rice leaf roller observed in rice fields on plant-diversified and mono-rice farms from 2001 to 2015.

(A) and (B) Pink rice borer; (C) and (D) Rice brown planthopper; (E) and (F) Rice leaf roller. The blue and red lines (in Figure 6A, C and E) indicate the plant-diversified and mono-rice farms, respectively. Vertical bars on each point denote SE. From 2001 to 2015, the number of trapped pink rice borers and rice brown planthoppers, and the population densities of rice leaf rollers were monitored from 10 April to 30 September, 11 May to 30 September, and 11 June to 20 September, respectively.

https://doi.org/10.7554/eLife.35103.005
Figure 2—source data 1

Pink rice borer: mean and standard deviation (individual per lamp per year) from the 15 year monitoring data, stratified by year and farm type.

https://doi.org/10.7554/eLife.35103.006
Figure 2—source data 2

Rice brown planthopper: mean and standard deviation (individual per lamp per year) from the 15 year monitoring data, stratified by year and farm type.

https://doi.org/10.7554/eLife.35103.007
Figure 2—source data 3

Rice leaf roller: mean and standard deviation (individual per ha per year) from the 15 year monitoring data, stratified by year and farm type.

https://doi.org/10.7554/eLife.35103.008
Figure 2—source data 4

Economic Injury Levels of pink rice borers, rice brown planthoppers and rice leaf rollers issued by Shanghai Agricultural Technology Extension and Service Center (SATESC).

‘/' denotes that there is no Economic Injury Level for rice leaf roller in grain-filling stage of rice.

https://doi.org/10.7554/eLife.35103.009
Abundance of predators observed on plant-diversified and mono-rice farms for each year.

Abundance of predators in the rice fields was sampled at an interval of 15–20 days (with minor variation due to weather conditions) from seedling stage to grain stage from 2007 to 2015. Vertical bars on each point denote SE.

https://doi.org/10.7554/eLife.35103.010
Figure 3—source data 1

Predator abundances: mean and standard deviation (individual per 100 rice clusters per year) from the 15 year monitoring data, stratified by year and farm type.

https://doi.org/10.7554/eLife.35103.011
Predator abundance on the border crop of soybeans and neighboring crops (maize, eggplant and Chinese cabbage) on plant-diversified farms.

(A) Predator abundance in different years; and (B) Predator abundance on four crops (soybean, maize, eggplant and Chinese cabbage). Abundance of predators (ladybird beetles, lacewings and spiders) were monitored in soybeans from 2007 to 2014 and in neighboring crops (maize, eggplant and Chinese cabbage) during 2009–2011 and 2013–2014. Vertical bars on each point denote SE.

https://doi.org/10.7554/eLife.35103.012
Dynamics of the number of insecticide sprays, the amount of insecticide sprayed and grain yield per crop on plant-diversified and mono-rice farms from 2001 to 2015.

(A) Number of insecticide sprays; (B) Amount of commercial insecticide sprayed (kg•ha−1); (C) Amount of active ingredient in insecticide sprayed (kg•ha−1); and (D) Grain yield (t•ha−1). Vertical bars on each point denote SE.

https://doi.org/10.7554/eLife.35103.013
Figure 5—source data 1

The amount of commercial insecticide and active ingredient sprayed per crop: mean and standard deviation (kg•ha−1) from the 15 year monitoring data, stratified by year and farm type.

https://doi.org/10.7554/eLife.35103.014
Figure 5—source data 2

The number of insecticide spray per crop: mean and standard deviation from the 15 year monitoring data, stratified by year and farm type.

https://doi.org/10.7554/eLife.35103.015
Figure 5—source data 3

Cost–benefit analysis of plant-diversified farms compared with mono-rice farms.

All data are mean values from 2001 to 2015; average grain price is 2.163 RMB per kilogram, and average soybean price is 3.873 RMB per kilogram; about 3% of one-hectare rice field was taken by soybeans in the field ridge, and soybean yield is about 25.0 kilograms per hectare rice field. Means ± SE.

https://doi.org/10.7554/eLife.35103.016
Figure 5—source data 4

Grain yield: mean and standard deviation (kg•ha−1) from the 15 year monitoring data, stratified by year and farm type.

https://doi.org/10.7554/eLife.35103.017
Figure 6 with 1 supplement
Effects of plant diversification in experiment in which plant-diversified with mono-rice farming were compared at the same locations.

(A) Density of rice plant-hoppers sampled in rice field plots; (B) Density of rice stem borers sampled in rice field plots; (C) Density of rice leaf rollers sampled in rice field plots; (D) Density of the predators (ladybird beetles, lacewings and spiders) sampled in rice field plots; (E) Amount of insecticide sprays per rice field plot (kg•ha−1); and (F) Grain yield per rice field (t•ha−1). Vertical bars denote SE.

https://doi.org/10.7554/eLife.35103.018
Figure 6—source data 1

Stem borer: mean and standard deviation (individual per 100 rice clusters) from the common-location-experiments, stratified by year, farm identity, and farm type.

https://doi.org/10.7554/eLife.35103.020
Figure 6—source data 2

Rice plant-hopper: mean and standard deviation (individual per 100 rice clusters) from the common-location-experiments, stratified by year, farm identity, and farm type.

https://doi.org/10.7554/eLife.35103.021
Figure 6—source data 3

Leaf roller: mean and standard deviation (individual per 100 rice clusters) from the common-location-experiments, stratified by year, farm identity, and farm type.

https://doi.org/10.7554/eLife.35103.022
Figure 6—source data 4

Predator: mean and standard deviation (individual per 100 rice clusters) from the common-location-experiments, stratified by year, farm identity, and farm type.

https://doi.org/10.7554/eLife.35103.023
Figure 6—source data 5

Insecticide amount: mean and standard deviation (kg•ha−1) from the common-location-experiments, stratified by year, farm identity, and farm type.

https://doi.org/10.7554/eLife.35103.024
Figure 6—source data 6

Yield: mean and standard deviation (kg•ha−1) from the common-location-experiments, stratified by year, farm identity, and farm type.

https://doi.org/10.7554/eLife.35103.025
Figure 6—figure supplement 1
Predator abundance in the border crop of soybeans and in the neighboring crop of maize sampled in rice field plots.

Vertical bars denote SE.

https://doi.org/10.7554/eLife.35103.019
Power analysis results for rice plant-hopper occurrence, where the power are estimated for additional experimental sites (left), additional replicates for each farm type–site–year block (middle), and additional years (right), based on the effect size estimated by the mixed-effect model fitted to the common-location experiment data.

The horizontal line marks the standard power level of 80%. Vertical line denotes the 95% confidence interval for the power estimates.

https://doi.org/10.7554/eLife.35103.026
Power analysis results for rice leaf roller occurrence.

See caption of Figure 7—figure supplement 1 for details.

https://doi.org/10.7554/eLife.35103.027
Power analysis results for predator abundance.

See caption of Figure 7—figure supplement 1 for details.

https://doi.org/10.7554/eLife.35103.028
Power analysis results for grain yield.

See caption of Figure 7—figure supplement 1 for details.

https://doi.org/10.7554/eLife.35103.029
A path diagram depicting the hypothesis on the relationships among the variables considered in this study.

‘+' indicates increased level and '-' indicates decreased level.

https://doi.org/10.7554/eLife.35103.030
The layout of each rice plots in each community farm and ‘Z’-style grain yield sampling.

On each farm, the rice growing area was divided into nine paddy plots, which were 60–70 × 25–35 m on each plot. Three to six rice field plots of 0.120–0.167 hectares were selected in each community farm to measure the grain yield each year. The rice plants at harvest stage (‘Z’-style sampling with 10, one square meter subplots in each plot) were mowed and threshed, and the grain yield per unit area was obtained. ‘×' and black solid dots denoted rice, and 1 m2 sampling areas for rice grain yield, respectively. The interval between two adjacent black solid dots was about five meters.

https://doi.org/10.7554/eLife.35103.031
The layout of plant-diversified fields in which a border crop (soybean) was interplanted around the rice fields and a neighboring crop (maize) was interplanted around the soybeans.

(A) Drawing plot diagram for plant-diversified fields; and (B) the photograph for plant-diversified fields. ‘×', ‘o’ and ‘§' denoted rice, soybean and maize, respectively. The layout of each control rice field was similar, but without soybeans or maize.

https://doi.org/10.7554/eLife.35103.032
Author response image 2
The correlation between number of insect pests and number of predators in rice field plots.

Here insect pests included rice planthoppers, rice stem borers, and rice leaf rollers; predators were involved in ladybird beetles, lacewings and spiders.

https://doi.org/10.7554/eLife.35103.036

Data availability

All data generated or analysed during this study are included in the manuscript and supporting files.

Additional files

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